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Border control refers to measures taken by a state or a bloc of states to monitor[1] and regulate the movement of people, animals, and goods across its borders, including land borders as well as airports and sea ports. In some cases, it can also refer to such controls imposed on internal borders within a single state. Border controls in the 21st century are tightly intertwined with

intricate systems of travel documents, visas, and increasingly complex policies that vary between countries. While some borders (including most states' internal borders and international borders within the Schengen Area) are open and completely unguarded, others (including the vast majority of borders between countries as well as some internal borders) are subject to some degree of

control and may be crossed legally only at designated checkpoints.

Contents

1 History

2 Internal border controls

2.1 Asia

2.2 Europe

2.3 North America

2.3.1 Contemporary

2.3.2 Historical

2.4 Realm of New Zealand

2.5 Apartheid-era South Africa

3 Aspects

3.1 Biosecurity

3.2 Customs

3.2.1 Customs area

3.2.2 Sanitary and phytosanitary measures

3.2.3 Duty-free shops

3.3 Air and maritime borders

3.4 Border security

3.4.1 Border checkpoints

3.4.1.1 Port of entry

3.4.1.2 Quilantan entry

3.4.2 Border zones

3.5 Drugs

3.6 Immigration law and policy

3.6.1 Diaspora communities

3.6.2 Special immigration areas

3.6.3 Local border traffic

3.6.4 Immigrant investor programmes

3.6.5 Open borders

3.7 International zones

3.7.1 Airport transit areas

3.7.2 Other examples

4 Travel documents

4.1 International Certificate of Vaccination

4.2 Diplomatic and Official Passports

4.3 Laissez-passer

4.4 Identity cards

4.5 Travel documents for permanent residents

4.6 Seafarers' identity documents

4.7 Indigenous nations

4.7.1 Indigenous passports

4.7.2 Certificate of Indigenous Status

4.7.3 Enhanced Tribal Identity Cards

4.7.4 Kikapoo I-872 Native American Card

4.7.5 American Samoans

4.8 Special travel documents

4.8.1 Certificate of identity

4.8.2 Chinese Travel Document

4.8.3 Israeli Travel Document in lieu of a National Passport

4.8.4 Passports without right of abode

4.8.5 Serbian Coordination Directorate Passports in Kosovo

4.9 Visas

5 Specific requirements

5.1 Biometrics

5.2 Immigration stamps

5.3 Exit controls

5.3.1 No exit control

5.3.2 Formal exit control without passport stamping

5.3.3 Exit permits

5.4 Nationality and travel history

5.5 Prescreening

5.5.1 Informal prescreening

6 Expedited border controls

6.1 British Isles

6.2 Asia and Oceania

6.3 North America

6.4 APEC Business Travel Card (ABTC)

7 Border control organisations by country

8 Controversies

8.1 America

8.1.1 Policies targeting Muslims

8.1.2 Separation of families seeking asylum

8.2 Bhutan

8.3 Israel

8.4 Australia

8.4.1 Offshore detention centres

8.4.2 Travel restrictions on Australian citizens during the COVID-19 pandemic

8.5 China

8.6 Cyprus and the European Union

8.7 Involvement of private companies

9 Gallery

10 See also

11 Notes

12 References

13 Further reading

14 External links

History

The purpose of the Great Wall of China was to stop the "barbarians" from crossing the northern border of China.

States and rulers have always regarded the ability to determine who enters or remains in their territories as a key test of their sovereignty, but prior to World War I, border controls were only sporadically implemented.[2] In medieval Europe, for example, the boundaries between rival countries and centres of power were largely symbolic or consisted of amorphous borderlands, 'marches',

and 'debatable lands' of indeterminate or contested status and the real 'borders' consisted of the fortified walls that surrounded towns and cities, where the authorities could exclude undesirable or incompatible people at the gates, from vagrants, beggars and the 'wandering poor', to 'masterless women', lepers, Romani, or Jews.[3]

Arabic papyrus with an exit permit, dated 24 January 722 AD, pointing to the regulation of travel activities. From Hermopolis Magna, Egypt

Chinese passport from the Qing Dynasty, 24th Year of the Guangxu Reign, 1898

The concept of border controls has its origins in antiquity. In Asia, the existence of border controls is evidenced in classical texts. The Arthashastra (c. 3rd century BCE) make mentions of passes issued at the rate of one masha per pass to enter and exit the country. Chapter 34 of the Second Book of Arthashastra concerns with the duties of the Mudrādhyakṣa (lit. 'Superintendent

of Seals') who must issue sealed passes before a person could enter or leave the countryside.[4] Passports resembling those issued today were an important part of the Chinese bureaucracy as early as the Western Han (202 BCE-220 CE), if not in the Qin Dynasty. They required such details as age, height, and bodily features.[5] These passports (zhuan) determined a person's ability to move

throughout imperial counties and through points of control. Even children needed passports, but those of one year or less who were in their mother's care may not have needed them.[5]

In the medieval Islamic Caliphate, a form of passport was the bara'a, a receipt for taxes paid. Border controls were in place to ensure that only people who paid their zakah (for Muslims) or jizya (for dhimmis) taxes could travel freely between different regions of the Caliphate; thus, the bara'a receipt was a "basic passport".[6]

In medieval Europe, passports were issued since at least the reign of Henry V of England, as a means of helping his subjects prove who they were in foreign lands. The earliest reference to these documents is found in a 1414 Act of Parliament.[7][8] In 1540, granting travel documents in England became a role of the Privy Council of England, and it was around this time that the term

"passport" was used. In 1794, issuing British passports became the job of the Office of the Secretary of State.[7] The 1548 Imperial Diet of Augsburg required the public to hold imperial documents for travel, at the risk of permanent exile.[9] During World War I, European governments introduced border passport requirements for security reasons, and to control the emigration of people

with useful skills. These controls remained in place after the war, becoming a standard, though controversial, procedure. British tourists of the 1920s complained, especially about attached photographs and physical descriptions, which they considered led to a "nasty dehumanisation".[10]

Starting in the mid-19th century, the Ottoman Empire established quarantine stations on many of its borders to control disease. For example, along the Greek-Turkish border, all travellers entering and exiting the Ottoman Empire would be quarantined for 9–15 days. These stations would often be manned by armed guards. If plague appeared, the Ottoman army would be deployed to enforce

border control and monitor disease.[11]

One of the earliest systematic attempts of modern nation states to implement border controls to restrict entry of particular groups were policies adopted by Canada, Australia, and America to curtail immigration of Asians in white settler states in the late 19th and early 20th centuries. The first anti-East Asian policy implemented in this era was the Chinese Exclusion Act of 1882 in

America, which was followed suit by the Chinese Immigration Act of 1885 in Canada, which imposed what came to be called the Chinese head tax. These policies was a sign of injustice and unfair treatment to the Chinese workers because the jobs they engaged in were mostly menial jobs.[12] Similar policies were adopted in various British colonies in Australia over the latter half of the 19th

century targeting Asian immigrants arriving as a result of the region's series of gold rushes[13] as well as Kanakas (Pacific Islanders brought into Australia as indentured labourers)[14] who alongside the Asians were perceived by trade unionists and White blue collar workers as a threat to the wages of White settlers.[15] Following the establishment of the Commonwealth of Australia in

1901, these discriminatory border control measures quickly expanded into the White Australia Policy, while subsequent legislation in America (e.g. the Immigration Act of 1891, the Naturalisation Act of 1906, and the Immigration Act of 1917) resulted in an even stricter policy targeting immigrants from both Asia and parts of southern and eastern Europe.

BN(O) passports sported a burgundy red cover, identical to that of the British Citizen passports, albeit without the words "European Union" text at the top part of the cover between 1990 and March 2020.

Even following the adoption of measures such as the White Australia Policy and the Chinese Exclusion Act in English-speaking settler colonies, pervasive control of international borders remained a relatively rare phenomenon until the early 20th century, prior to which many states had open international borders either in practice or due to a lack of any legal restriction. John Maynard

Keynes identified World War I in particular as the point when such controls became commonplace.[16]

Decolonisation during the twentieth century saw the emergence of mass emigration from nations in the Global South, thus leading former colonial occupiers to introduce stricter border controls.[17] In the United Kingdom this process took place in stages, with British nationality law eventually shifting from recognising all Commonwealth citizens as British subjects to today's complex

British nationality law which distinguishes between British citizens, modern British Subjects, British Overseas Citizens, and overseas nationals, with each non-standard category created as a result of attempts to balance border control and the need to mitigate statelessness. This aspect of the rise of border control in the 20th century has proven controversial. The British Nationality

Law 1981 has been criticised by experts,[a] as well as by the Committee on the Elimination of Racial Discrimination of the United Nations,[b] on the grounds that the different classes of British nationality it created are, in fact, closely related to the ethnic origins of their holders.

The creation of British Nationality (Overseas) status, for instance, (with fewer privileges than British citizen status) was met with criticism from many Hong Kong residents who felt that British citizenship would have been more appropriate in light of the "moral debt" owed to them by the UK.[c][d] Some British politicians[e] and magazines[f] also criticised the creation of BN(O) status.

In 2020, the British government under Boris Johnson announced a programme under which BN(O)s would have leave to remain in the UK with rights to work and study for five years, after which they may apply for settled status. They would then be eligible for full citizenship after holding settled status for 12 months.[23] This was implemented as the eponymously named "British National

(Overseas) visa", a residence permit that BN(O)s and their dependent family members have been able to apply for since 31 January 2021.[24][25] BN(O)s and their dependents who arrived in the UK before the new immigration route became available were granted "Leave Outside the Rules" at the discretion of the Border Force to remain in the country for up to six months as a temporary

measure.[26] In effect, this retroactively granted BN(O)s a path to right of abode in the United Kingdom. Despite the COVID-19 pandemic, about 7,000 people had entered the UK under this scheme between July 2020 and January 2021.[27]

Ethnic tensions created during colonial occupation also resulted in discriminatory policies being adopted in newly independent African nations, such as Uganda under Idi Amin which banned Asians from Uganda, thus creating a mass exodus of the (largely Gujarati[28][29]) Asian community of Uganda. Such ethnically driven border control policies took forms ranging from anti-Asian sentiment in

East Africa to Apartheid policies in South Africa and Namibia (then known as Southwest Africa under South African rule) which created bantustans[g] and pass laws[h] to segregate and impose border controls against non-whites, and encouraged immigration of whites at the expense of Blacks as well as Indians and other Asians. Whilst border control in Europe and east of the Pacific have

tightened over time,[17] they have largely been liberalised in Africa, from Yoweri Museveni's reversal of Idi Amin's anti-Asian border controls[i] to the fall of Apartheid (and thus racialised border controls) in South Africa.

The development of border control policies over the course of the 20th century also saw the standardisation of refugee travel documents under the Convention Relating to the Status of Refugees of 1951[j] and the 1954 Convention travel document[36] for stateless people under the similar 1954 statelessness convention.

The COVID-19 pandemic in 2020 produced a drastic tightening of border controls across the globe. Many countries and regions have imposed quarantines, entry bans, or other restrictions for citizens of or recent travellers to the most affected areas.[37] Other countries and regions have imposed global restrictions that apply to all foreign countries and territories, or prevent their own

citizens from travelling overseas.[38] The imposition of border controls has curtailed the spread of the virus, but because they were first implemented after community spread was established in multiple countries in different regions of the world, they produced only a modest reduction in the total number of people infected[39] These strict border controls economic harm to the tourism

industry through lost income and social harm to people who were unable to travel for family matters or other reasons. When the travel bans are lifted, many people are expected to resume traveling. However, some travel, especially business travel, may be decreased long-term as lower cost alternatives, such as teleconferencing and virtual events, are preferred.[40] A possible long-term

impact has been a decline of business travel and international conferencing, and the rise of their virtual, online equivalents.[41] Concerns have been raised over the effectiveness of travel restrictions to contain the spread of COVID-19.[42]

Internal border controls

Internal border controls are measures implemented to control the flow of people or goods within a given country. Such measures take a variety of forms ranging from the imposition of border checkpoints to the issuance of internal travel documents and vary depending on the circumstances in which they are implemented. Circumstances resulting in internal border controls include increasing

security around border areas (e.g. internal checkpoints in America or Bhutan near border regions), preserving the autonomy of autonomous or minority areas (e.g. border controls between Peninsular Malaysia, Sabah, and Sarawak; border controls between Hong Kong, Macau, and mainland China), preventing unrest between ethnic groups (e.g. Northern Ireland's peace walls, border controls in

Tibet and Northeastern India), and disputes between rival governments (e.g. between the Republic of China and the People's Republic of China).

During the COVID-19 pandemic, temporary internal border controls were introduced in jurisdictions across the globe. For instance, travel between Australian states and territories was prohibited or restricted by state governments at various points of the pandemic either in conjunction with sporadic lockdowns or as a stand-alone response to COVID-19 outbreaks in neighbouring

states.[43][44][45] Internal border controls were also introduced at various stages of Malaysia's Movement Control Order, per which interstate travel was restricted depending on the severity of ongoing outbreaks. Similarly, internal controls were introduced by national authorities within the Schengen Area, though the European Union ultimately rejected the idea of suspending the Schengen

Agreement per se.[46][47]

Asia

Internal border controls exist in many parts of Asia. For example, travellers visiting minority regions in India and China often require special permits to enter.[k] Internal air and rail travel within non-autonomous portions of India and mainland China also generally require travel documents to be checked by government officials as a form of interior border checkpoint. For such travel

within India, Indian citizens may utilise their Voter ID, National Identity Card, passport, or other proof of Indian citizenship whilst Nepali nationals may present any similar proof of Napali citizenship. Meanwhile, for such travel within mainland China, Chinese nationals from the mainland are required to use their national identity cards.

Within China, extensive border controls are maintained for those travelling between the mainland, special administrative regions of Hong Kong and Macau, and areas controlled by the Republic of China.[l] Foreign nationals need to present their passports or other required types of travel documents when travelling between these areas. For Chinese nationals (including those with British

National (Overseas) status), there are special documents[m] for travel between these territories. Similar arrangements exist for travel between territories controlled by the Republic of China and territories controlled by the People's Republic of China. [n] Internal border controls in China have also resulted in the creation of special permits allowing Chinese citizens to immigrate to or

reside in other immigration areas within the country.[o]

China also maintains distinct, relaxed border control policies in the Special Economic Zones of Shenzhen, Zhuhai and Xiamen.[50][51] Nationals of most countries[p] can obtain a limited area visa upon arrival in these regions, which permit them to stay within these cities without proceeding further into other parts of Mainland China. Visas for Shenzhen are valid for 5 days, and visas for

Xiamen and Zhuhai are valid for 3 days. The duration of stay starts from the next day of arrival.[53] The visa can only be obtained only upon arrival at Luohu Port, Huanggang Port Control Point, Fuyong Ferry Terminal or Shekou Passenger Terminal for Shenzhen;[54] Gongbei Port of Entry, Hengqin Port or Jiuzhou Port for Zhuhai;[55] and Xiamen Gaoqi International Airport for Xiamen.[56]

Similarly, China permits nationals of non—visa-exempt ASEAN countries[q] to visit Guilin without a visa for a maximum of 6 days if they travel with an approved tour group and enter China from Guilin Liangjiang International Airport. They may not visit other cities within Guangxi or other parts of Mainland China.[57]

Meanwhile, in Bhutan, a microstate accessible by road only through India, there are interior border checkposts (primarily on the Lateral Road) and, additionally, certain areas require special permits to enter, whilst visitors not proceeding beyond the border city of Phuentsholing do not need permits to enter for the day (although such visitors are de facto subject to Indian visa policy

since they must proceed through Jaigaon). Individuals who are not citizens of India, Bangladesh, or the Maldives are not allowed to proceed past Phuentsholing by land and are instead required to arrive by air at the country's sole international airport in Paro, which has flights from India and other countries in the Greater India region such as Thailand, Singapore, and Nepal.

More generally, authorities in mainland China maintain a system of residency registration known as hukou (Chinese: 户口; lit. 'household individual'), by which government permission is needed to formally change one's place of residence. It is enforced with identity cards. This system of internal border control measures effectively limited internal migration before the 1980s but

subsequent market reforms caused it to collapse as a means of migration control. An estimated 150 to 200 million people are part of the "blind flow" and have unofficially migrated, generally from poor, rural areas to wealthy, urban ones. However, unofficial residents are often denied official services such as education and medical care and are sometimes subject to both social and

political discrimination. In essence, the denial of social services outside an individual's registered area of residence functions as an internal border control measure geared toward dissuading migration within the mainland.

The Hộ khẩu system in Vietnam is similar to the Hukou system in mainland China. Local authorities issue each household a "household registration book" or sổ hộ khẩu, in which the basic biographical information of each household member is recorded. The sổ hộ khẩu is the ultimate legal proof of residence in Vietnam. Together with the "citizen identification card" or giấy

chứng minh nhân dân/căn cước công dân, the sổ hộ khẩu constitutes the most important legal identification document in Vietnam. Modeled after the Chinese hukou system and originally used in urban areas only, hộ khẩu functioned as a way to manage urban growth and limit how many people moved, as well as who moved in and out of the cities.[58] Gradually, the system became

a universal method of control as its application expanded to the countryside.[59] Presently, the system defines four types of residence, KT1 through KT4. KT1 is the primary and permanent type of residence, and denotes a person's primary residential address. If this person moves on a semi-permanent basis to another place within the same province or national municipality (within Saigon,

for example), then he or she needs to register for a KT2 residential status at that new address. If this same move happens across provincial borders, then the person has to sign up for a KT3 registration. For migrant workers and students temporarily residing outside of their province or national municipality of permanent residence, they need to apply for a KT4 registration.[58]

Navigating this matrix of regulations is tough. But the public security apparatus that manages the hộ khẩu system is also difficult to deal with, especially if one is a poor migrant worker with little to no formal education. Yet hộ khẩu remains absolutely crucial, especially for the poor. It is tied to access to welfare benefits, and, in the case of children, the right to attend

public school.[60] For a migrant family in Saigon with no KT3 or KT4 registration, subsidised medical care, poverty assistance, and almost-free schooling are all out of reach.[59] Much like its counterpart in mainland China, the denial of services outside an individual's place of registered residence resulting from this system of internal border control serves to dissuade internal

migration.

Another example is the Malaysian states of Sabah and Sarawak, which have maintained their own border controls[61] since joining Malaysia in 1963. The internal border control is asymmetrical; while Sabah and Sarawak impose immigration control on Malaysian citizens from other states, there is no corresponding border control in Peninsular Malaysia, and Malaysians from Sabah and Sarawak have

unrestricted right to live and work in the Peninsular. For social and business visits less than three months, Malaysian citizens may travel between the Peninsular, Sabah and Sarawak using the Malaysian identity card (MyKad) or Malaysian passport, while for longer stays in Sabah and Sarawak they are required to have an Internal Travel Document or a passport with the appropriate

residential permit.

The most restrictive internal border controls are in North Korea. Citizens are not allowed to travel outside their areas of residence without explicit authorisation, and access to the capital city of Pyongyang is heavily restricted.[62][63] Similar restrictions are imposed on tourists, who are only allowed to leave Pyongyang on government-authorised tours to approved tourist sites.

Domestic Immigration stamp permitting entry into the Andaman and Nicobar Islands in India.

Sample of a One Way Travel Permit for internal emigration from mainland China to Hong Kong or Macau.

Sample of a Special Economic Zone visa issued on arrival in China

Data page of a booklet type internal travel document issued by Taiwan authorities to a Mainland Chinese resident.

Malaysian entry stamps specify which jurisdictions (i.e. West or Peninsular Malaysia, Sabah, and Sarawak) the bearer is permitted to enter, and there are immigration checks when entering each.

The entrance to the building of the Shenzhen Bay Control Point, an internal border checkpoint between Hong Kong and the Chinese mainland

The Tibet Travel Permit, required to enter the Tibet Autonomous Region, is an example of internal border controls in minority regions of China and India. Other similar documents include Restricted Area Permits and Protected Area permits primarily issued to enter India's northeast.

Front and back of mainland residence permits for Chinese citizens from Hong Kong and Macau (left) and Chinese citizens from areas administered by the Republic of China (right)

internal travel document issued to Chinese citizens from the mainland for travel to and from Hong Kong and Macau

Exit endorsements affixed to the back of an internal travel document issued to Chinese citizens from the mainland for travel to and from Hong Kong or Macau

An internal travel document issued to Chinese citizens from areas administered by the Republic of China to travel to and from the mainland

Internal travel document for Chinese citizens of Hong Kong or Macau to enter the mainland.

The inside pages of hukou booklet in China.

Europe

The red lines indicate temporary internal border controls within the Schengen Area. The blue area represents members of the Schengen area, the green area represents European Union members not in the Schengen Area, and the grey area represents the rest of western Europe.

An example from Europe is the implementation of border controls on travel between Svalbard, which maintains a policy of free migration as a result of the Svalbard Treaty and the Schengen Area, which includes the rest of Norway. Other examples of effective internal border controls in Europe include the closed cities of certain CIS members, areas of Turkmenistan that require special

permits to enter, restrictions on travel to the Gorno-Badakhshan Autonomous Region in Tajikistan, and (depending on whether Northern and Southern Cyprus are considered separate countries) the Cypriot border. Similarly, Iraq's Kurdistan region maintains a separate and more liberal visa and customs area from the rest of the country, even allowing visa free entry for Israelis whilst the

rest of the country bans them from entering. Denmark also maintains a complex system of subnational countries which, unlike the Danish mainland, are outside the European Union and maintain autonomous customs policies.[r] In addition to the numerous closed cities of Russia,[64] parts of 19 subjects[s] of the Russian Federation are closed for foreigners without special permits and are

consequently subject to internal border controls.[65]

Another complex border control situation in Europe pertains to the United Kingdom. Whilst the crown dependencies are within the Common Travel Area, neither Gibraltar nor the sovereign British military exclaves of Akrotiri and Dhekelia are. The former maintains its own border control policies, thus requiring physical border security at its border with the Schengen Area as well as the

implementation of border controls for travellers proceeding directly between Gibraltar and the British mainland. The latter maintains a relatively open border with Southern Cyprus, though not with Northern Cyprus. Consequently, it is a de facto member of the Schengen Area and travel to or from the British mainland requires border controls. On 31 December 2020, Spain and the United

Kingdom reached an agreement in principle under which Gibraltar would join the Schengen Area,[66] clearing the way for the European Union and the UK to start formal negotiations on the matter.[67]

In the aftermath of Brexit, border controls for goods flowing between Great Britain and Northern Ireland were introduced in accordance with the Protocol on Ireland/Northern Ireland agreed to as part of the UK's withdrawal agreement with the EU.[68] Due to the thirty-year internecine conflict in Northern Ireland, the UK-Ireland border has had a special status since that conflict was ended

by the Belfast Agreement/Good Friday Agreement of 1998. As part of the Northern Ireland Peace Process, the border has been largely invisible, without any physical barrier or custom checks on its many crossing points; this arrangement was made possible by both countries' common membership of both the EU's Single Market and Customs Union and of their Common Travel Area. Upon the UK's

withdrawal from the European Union, the border in Ireland became the only land border between the UK and EU. EU single market and UK internal market provisions require certain customs checks and trade controls at their external borders. The Northern Ireland Protocol is intended to protect the EU single market, while avoiding imposition of a 'hard border' that might incite a recurrence of

conflict and destabilise the relative peace that has held since the end of the Troubles. Under the Protocol, Northern Ireland is formally outside the EU single market, but EU free movement of goods rules and EU Customs Union rules still apply; this ensures there are no customs checks or controls between Northern Ireland and the rest of the island. In place of an Ireland/Northern Ireland

land border, the protocol has created a de facto customs border down the Irish Sea for customs purposes, separating Northern Ireland from the island of Great Britain,[69][70] to the disquiet of prominent Unionists.[71] To operate the terms of the protocol, the United Kingdom must provide border control posts at Northern Ireland's ports:[71] actual provision of these facilities is the

responsibility of Northern Ireland's Department of Agriculture, Environment and Rural Affairs (DAERA).[71] Temporary buildings were put in place for 1 January 2021, but in February 2021, the responsible Northern Ireland minister, Gordon Lyons (DUP), ordered officials to stop work on new permanent facilities and to stop recruiting staff for them.[72] In its half yearly financial report 26

August 2021, Irish Continental Group, which operates ferries between Great Britain and the Republic of Ireland, expressed concern at the lack of implementation of checks on goods arriving into Northern Ireland from Great Britain, as required under the protocol. The company said that the continued absence of these checks (on goods destined for the Republic of Ireland) is causing a

distortion in the level playing field, since goods that arrive directly into Republic of Ireland ports from Great Britain are checked on arrival.[73] The implementation of border controls between Great Britain and Northern Ireland was the primary catalyst for the 2021 Northern Ireland riots.

An unusual example of internal border controls pertains to customs enforcement within the Schengen area. Even though borders are generally invisible, the existence of areas within the Schengen area but outside the European Union Value Added Tax Area, as well as jurisdictions such as Andorra which are not officially a part of the Schengen area but can not be accessed without passing

through it, has resulted in the existence of sporadic internal border controls for customs purposes. Additionally, as per Schengen area rules,[74] hotels and other types of commercial accommodation must register all foreign citizens, including citizens of other Schengen states, by requiring the completion of a registration form by their own hand. [t] The Schengen rules do not require any

other procedures; thus, the Schengen states are free to regulate further details on the content of the registration forms, and identity documents which are to be produced, and may also require the persons exempted from registration by Schengen laws to be registered. A Schengen state is also permitted to reinstate border controls with another Schengen country for a short period where

there is a serious threat to that state's "public policy or internal security" or when the "control of an external border is no longer ensured due to exceptional circumstances".[76] When such risks arise out of foreseeable events, the state in question must notify the European Commission in advance and consult with other Schengen states.[77] Since the implementation of the Schengen

Agreement, this provision has been invoked frequently by member states, especially in response to the European migrant crisis.[u]

The Israeli military maintains an intricate network of internal border controls within Israeli and Palestinian territory restricting the freedom of movement of Palestinians, composed of permanent, temporary, and random manned checkpoints in the West Bank; the West Bank Barrier; and restrictions on the usage of roads by Palestinians.[80] Spread throughout the State of Israel and the areas

of the State of Palestine under de facto Israeli control, internal border control measures are a key feature of Israeli and Palestinian life and are among the most restrictive in the world. Additionally, the blockade of the Gaza Strip results in a de facto domestic customs and immigration border for Palestinians. In order to clear internal border controls, Palestinians are required to

obtain a variety of permits from Israeli authorities depending on the purpose and area of their travel. The legality and impact of this network of internal border controls is controversial. B'Tselem, an Israeli non-governmental organisation that monitors human rights in Palestine, argues that they breach the rights guaranteed by the International Covenant on Economic, Social and Cultural

Rights—in particular, the right to a livelihood, the right to an acceptable standard of living, the right to satisfactory nutrition, clothing, and housing, and the right to attain the best standard of physical and mental health.[81] B'Tselem also argues that the restrictions on ill, wounded and pregnant Palestinians seeking acute medical care is in contravention of international law

that states that medical professionals and the sick must be granted open passage.[82] While Israeli Supreme Court has deemed the measures acceptable for security reasons, Haaretz's Amira Hass argues this policy defies one of the principles of the Oslo Accords, which states that Gaza and the West Bank constitute a single geographic unit.[83]

Much like relations between Jewish settlers in Israel and the native Palestinian population, strained intercommunal relations in Northern Ireland between Irish Catholics and the descendants of Protestant settlers from England and Scotland have resulted in de facto internal checkpoints. The peace lines are an internal border security measure to separate predominantly republican and

nationalist Catholic neighbourhoods from predominantly loyalist and unionist Protestant neighbourhoods. They have been in place in some form or another since the end of The Troubles in 1998, with the Good Friday Agreement. The majority of peace walls are located in Belfast, but they also exist in Derry, Portadown, and Lurgan,[84] with more than 32 kilometres of walls in Northern

Ireland.[85] The peace lines range in length from a few hundred metres to over 5 kilometres. They may be made of iron, brick, steel or a combination of the three and are up to 8 metres high.[86][84] Some have gates in them (sometimes staffed by police) that allow passage during daylight but are closed at night.

Banner opposing post-Brexit border controls between Great Britain and Northern Ireland seen in Sandy Row (March 2021)

Graffiti in Belfast opposing an "Irish Sea border" (February 2021)

A 5.5m high peace line along Springmartin Road in Belfast, with a fortified police station at one end

The peace line along Cupar Way in Belfast, seen from the predominantly Protestant side

The peace line at Bombay Street/Cupar Way in Belfast, seen from the predominantly Catholic side

Gates in a peace line in West Belfast

Israeli checkpoint outside the Palestinian city of Ramallah. August 2004

Vehicles queuing at Kalandia checkpoint in Palestine, August 2004

Huwwara checkpoint, south of the Palestinian city of Nablus.[87]

Central entry checkpoint to the closed city of Seversk, Tomsk Oblast, Russia.

As a consequence of Svalbard's unique immigration status and exclusion from the rest of Norway for border control purposes, the city of Barentsburg is predominantly Russian and hosts the world's second northernmost statue of Lenin (the northernmost is in Pyramiden).

Border post between France and Andorra, a microstate that de facto follows Schengen immigration policies and utilises the Euro as its national currency yet is not a part of the European Union VAT and customs areas.

The Italy-Switzerland border is an internal Schengen border, but as seen at this border crossing at Chiasso, there are border control facilities since Switzerland maintains its own customs and tax area.

North America

Contemporary

See also: Hyder-Stewart Border Crossing, Cornwall Island (Ontario), and Akwesasne

American Samoa entry stamp

Hyder, Alaska has no border controls for travellers entering from Canada, and travellers flying between Hyder and other Alaskan cities by seaplane undergo internal border control

Multiple types of internal border controls exist in America. While the American territories of Guam and the Northern Mariana Islands follow the visa policy of the United States, together, they also maintain their own visa waiver programme for certain nationalities.[88] Since the two territories are outside the customs territory of the United States, there are customs inspections when

travelling between them, and the rest of America. American Samoa has its own customs and immigration regulations, thus travelling between it and other American jurisdictions involves both customs and immigration inspections. The Virgin Islands are a special case, falling within the American immigration zone and solely following American visa policy, but being a customs free territory. As

a result, there are no immigration checks between the two, but travellers arriving in Puerto Rico or the American mainland directly from the Virgin Islands are subject to border control for customs inspection. America also maintains interior checkpoints, similar to those maintained by Bhutan, along its borders with Mexico and Canada, subjecting people to border controls even after they

have entered the country.

The Akwesasne nation; with territory in Ontario, Quebec, and New York; features several de facto internal border controls. As a result of protests by Akwesasne residents on their rights to cross the border unimpeded, as provided under the 1795 Jay Treaty, the Canada Border Services Agency closed its post on Cornwall Island, instead requiring travellers to proceed to the checkpoint in the

city of Cornwall. As a consequence of the arrangement, residents of the island are required to clear border controls when proceeding North to the Ontarian mainland, as well as when proceeding South to Akwesasne territory in New York, thus constituting internal controls both from a Canadian perspective and from the perspective of the Akwesasne nation. Similarly, travelling between Canada

and the Quebec portion of the Akwesasne nation requires driving through the state of New York, meaning that individuals will be required to clear American controls when leaving Quebec proper and to clear Canadian border controls when entering Quebec proper, though Canada does not impose border controls when entering the Quebec portion of the Akwesasne nation. Nevertheless, for residents

who assert a Haudenosaunee national identity distinct from Canadian or American citizenship, the intricate network of Canadian and American border controls are seen as a foreign-imposed system of internal border controls, similar to the Israeli checkpoints in Palestinian territory.[89][90]

The city of Hyder, Alaska has also been subject to internal border controls since America chose to stop regulating arrivals in Hyder from British Columbia. Since travellers exiting Hyder into Stewart, British Columbia are subject to Canadian border controls, it is theoretically possible for someone to accidentally enter Hyder from Canada without their travel documents and then to face

difficulties since both America and Canada would subject them to border controls that require travel documents. At the same time, however, the northern road connecting Hyder to uninhabited mountain regions of British Columbia is equipped with neither American nor Canadian border controls, meaning that tourists from Canada proceeding northwards from Hyder are required to complete Canadian

immigration formalities when they return to Stewart despite never having cleared American immigration.

Historical

Further information: Pass system (Canadian history), Slavery in the United States, and Slavery in the colonial history of the United States

In the past, internal border control measures were utilised by authorities in North America to control the movements of Indigenous or enslaved persons. Such systems typically took the form of an internal passport required for Indigenous or enslaved individuals to travel beyond their reserve or plantation.

In 1885 the "pass system" of internal border controls targeting Indigenous peoples was instituted in Canada. Introduced at the time of the North-West Rebellion, it remained in force until 1951.[91] Any Indigenous person caught outside his Indian reserve without a pass issued by an Indian agent was returned to the reserve or incarcerated.

Throughout the Thirteen Colonies before the Revolutionary War, slaves confined to homes or agricultural plantations, or whose movements were limited by curfews, could be required to furnish written evidence their owner had granted an exemption to permit their free movement. For example, the New Hampshire Assembly in 1714 passed "An Act To Prevent Disorders In The Night":[92][93]

Whereas great disorders, insolencies and burglaries are oft times raised and committed in the night time by Indian, Negro, and Molatto Servants and Slaves to the Disquiet and hurt of her Majesty, No Indian, Negro, or Molatto is to be from Home after 9 o'clock.

Notices emphasizing the curfew were published in The New Hampshire Gazette in 1764 and 1771.[92]

Internal passports were required for African Americans in the southern slave states before the American Civil War, for example, an authenticated internal passport dated 1815 was presented to Massachusetts citizen George Barker to allow him to freely travel as a free black man to visit relatives in slave states.[94] After many of these states seceded, forming the Confederate States of

America, the Confederate government introduced internal passports for whites as well.[95]

Realm of New Zealand

Niue entry stamp issued at Hanan International Airport

Main article: Visa policy of New Zealand

Further information: Realm of New Zealand

Tokelau, Niue, and the Cook Islands (Cook Islands Māori: Kūki 'Āirani)[96] maintain independent and less restrictive border controls from New Zealand. The Cook Islands further maintain a separate nationality law. Additionally, border controls for Tokelau are complicated by the fact that the territory is, for the most part, only accessible via Samoa.

Apartheid-era South Africa

Main article: Pass laws

Demonstrators discarding their passbooks to protest apartheid, 1960

In South Africa prior to the end of Apartheid, pass laws were a form of internal passport system designed to segregate the population, manage urbanisation, and allocate migrant labour. Also known as the natives' law, pass laws severely limited the movements of not only black African citizens, but other people as well by requiring or designated areas. Before the 1950s, this legislation

largely applied to African men, and attempts to apply it to women in the 1910s and 1950s were met with significant protests. Pass laws were one of the dominant features of the country's apartheid system until it was effectively ended in 1986. The first internal passports in South Africa were introduced on 27 June 1797 by the Earl Macartney in an attempt to prevent Africans from entering

the Cape Colony.[97] The Cape Colony was merged with the two Afrikaners republics in southern Africa to form the Union of South Africa in 1910. By this time, versions of pass laws existed elsewhere. A major boost for their utilization was the rise of the mining sector from the 1880s: pass laws provided a convenient means of controlling workers' mobility and enforcing contracts. In 1896

the South African Republic brought in two pass laws which required Africans to carry a metal badge. Only those employed by a master were permitted to remain on the Rand. Those entering a "labour district" needed a special pass which entitled them to remain for three days.[98] The Natives (Urban Areas) Act of 1923 deemed urban areas in South Africa as "white" and required all black

African men in cities and towns to carry around permits called "passes" at all times. Anyone found without a pass would be arrested immediately and sent to a rural area. It was replaced in 1945 by the Natives (Urban Areas) Consolidation Act, which imposed "influx control" on black men and also set up guidelines for removing people deemed to be living idle lives from urban areas. This act

outlined requirements for African peoples' "qualification" to reside legally in white metropolitan areas. To do so, they had to have Section 10 rights, based on whether[99]

the person had been born there and resided there always since birth;

the person had laboured continuously for ten years in any agreed area for any employer, or lived continuously in any such area for fifteen years;

The Black (Natives) Laws Amendment Act of 1952 amended the 1945 Native Urban Areas Consolidation Act, stipulating that all black people over the age of 16 were required to carry passes and that no black person could stay in an urban area more than 72 hours unless allowed to by Section 10.[100] The Natives (Abolition of Passes and Co-ordination of Documents) Act of 1952, commonly known as

the Pass Laws Act, repealed the many regional pass laws and instituted one nationwide pass law, which made it compulsory for all black South Africans over the age of 16 to carry the "passbook" at all times within white areas. The law stipulated where, when, and for how long a person could remain.[101]

The document was similar to an internal passport, containing details on the bearer such as their fingerprints, photograph, the name of his/her employer, his/her address, how long the bearer had been employed, as well as other identification information. Employers often entered a behavioural evaluation, on the conduct of the pass holder. An employer was defined under the law and could

only be a white person. The pass also documented permission requested and denied or granted to be in a certain region and the reason for seeking such permission. Under the terms of the law, any government employee could strike out such entries, basically cancelling the permission to remain in the area. A passbook without a valid entry then allowed officials to arrest and imprison the

bearer of the pass. These passes often became the most despised symbols of apartheid. The resistance to the Pass Law led to many thousands of arrests and was the spark that ignited the Sharpeville Massacre on 21 March 1960, and led to the arrest of Robert Sobukwe that day.

Aspects

Contemporary border control policies are complex and address a variety of distinct phenomena depending on the circumstances and political priorities of the state(s) implementing them. Consequently, there are several aspects of border control which vary in nature and importance from region to region.

Biosecurity

Quarantine operations deployed by mainland Chinese border control.

An International Certificate of Vaccination issued by the Bureau of Quarantine in the Philippines to an individual after being vaccinated with a COVID-19 vaccine in 2021.

Main articles: Biosecurity, Quarantine, Travel restrictions related to the COVID-19 pandemic, and Vaccination requirements for international travel

Biosecurity refers to measures aimed at preventing the introduction and/or spread of harmful organisms (e.g. viruses, bacteria, etc.) to animals and plants in order to mitigate the risk of transmission of infectious disease. In agriculture, these measures are aimed at protecting food crops and livestock from pests, invasive species, and other organisms not conducive to the welfare of the

human population. The term includes biological threats to people, including those from pandemic diseases and bioterrorism. The definition has sometimes been broadened to embrace other concepts, and it is used for different purposes in different contexts.

The most common category of biosecurity policies are quarantine measures adopted to counteract the spread of disease and, when applied as a component of border control, focus primarily on mitigating the entry of infected individuals, plants, or animals into a country.[102] Other aspects of biosecurity related to border control include mandatory vaccination policies for inbound travellers

and measures to curtail the risk posed by bioterrorism or invasive species.

Quarantine measures are frequently implemented with regard to the mobility of animals, including both pets and livestock. Notably, in order to reduce the risk of introducing rabies from continental Europe, the United Kingdom used to require that dogs, and most other animals introduced to the country, spend six months in quarantine at an HM Customs and Excise pound. This policy was

abolished in 2000 in favour of a scheme generally known as Pet Passports, where animals can avoid quarantine if they have documentation showing they are up to date on their appropriate vaccinations.[103]

In the past, quarantine measures were implemented by European countries in order to curtail the Bubonic Plague and Cholera. In the British Isles, for example, the Quarantine Act 1710 (9 Ann.) established maritime quarantine policies in an era in which strict border control measures as a whole were yet to become mainstream.[104] The first act was called for due to fears that the plague

might be imported from Poland and the Baltic states. The second act of 1721 was due to the prevalence of the plague at Marseille and other places in Provence, France. It was renewed in 1733 after a new outbreak in continental Europe, and again in 1743, due to an epidemic in Messina. In 1752 a rigorous quarantine clause was introduced into an act regulating trade with the Levant, and

various arbitrary orders were issued during the next twenty years to meet the supposed danger of infection from the Baltic states. Although no plague cases ever came to England during that period, the restrictions on traffic became more stringent, and in 1788 a very strict Quarantine Act was passed, with provisions affecting cargoes in particular. The act was revised in 1801 and 1805,

and in 1823–24 an elaborate inquiry was followed by an act making quarantine only at the discretion of the Privy Council, which recognised yellow fever or other highly infectious diseases as calling for quarantine, along with plague. The threat of cholera in 1831 was the last occasion in England of the use of quarantine restrictions. Cholera affected every country in Europe despite all

efforts to keep it out. When cholera returned to England in 1849, 1853 and 1865–66, no attempt was made to seal the ports. In 1847 the privy council ordered all arrivals with a clean bill of health from the Black Sea and the Levant to be admitted, provided there had been no case of plague during the voyage and afterwards, the practice of quarantine was discontinued.[105]

In modern maritime law, biosecurity measures for arriving vessels centre around 'pratique', a licence from border control officials permitting a ship to enter port on assurance from the captain that that the vessel is free from contagious disease. The clearance granted is commonly referred to as 'free pratique'. A ship can signal a request for 'pratique' by flying a solid yellow

square-shaped flag. This yellow flag is the Q flag in the set of international maritime signal flags.[106] In the event that 'free pratique' is not granted, a vessel will be held in quarantine according to biosecurity rules prevailing at the port of entry until a border control officer inspects the vessel.[107] During the COVID-19 pandemic, a controversy arose as to who granted pratique

to the Ruby Princess.[108] A related concept is the 'bill of health', a document issued by officials of a port of departure indicating to the officials of the port of arrival whether it is likely that the ship is carrying a contagious disease, either literally on board as fomites or via its crewmen or passengers. As defined in a consul's handbook from 1879:

A bill of health is a document issued by the consul or the public authorities of the port which a ship sails from, descriptive of the health of the port at the time of the vessel's clearance. A clean bill of health certifies that at the date of its issue no infectious disease was known to exist either in the port or its neighbourhood. A suspected or touched bill of health reports that

rumours were in circulation that an infectious disease had appeared but that the rumour had not been confirmed by any known cases. A foul bill of health or the absence of a clean bill of health implies that the place the vessel cleared from was infected with a contagious disease. The two latter cases would render the vessel liable to quarantine.[109]

Another category of biosecurity measures adopted by border control organisations is mandatory vaccination. As a result of the prevalence of Yellow Fever across much of the African continent, a significant portion of countries in the region require arriving passengers to present an International Certificate of Vaccination or Prophylaxis (Carte Jaune) certifying that they have received the

Yellow Fever vaccine. A variety of other countries require travellers who have visited areas where Yellow Fever is endemic to present a certificate in order to clear border checkpoints as a means of preventing the spread of the disease. Prior to the emergence of COVID-19, Yellow Fever was the primary human disease subjected to de facto vaccine passport measures by border control

authorities around the world. Similar measures are in place with regard to Polio and meningococcal meningitis in regions where those diseases are endemic and countries bordering those regions. Prior to the eradication of Smallpox, similar Carte Jaune requirements were in force for that disease around the world.

A road sign at an exit on Interstate 91 in Vermont advising individuals entering the state of a quarantine policy adopted in response to COVID-19, photographed in November 2020.

Slovakia, which otherwise maintains open borders with other Schengen Area jurisdictions, closed borders to non-residents because of the COVID-19 pandemic.

As a result of the COVID-19 pandemic, biosecurity measures have become a highly visible aspect of border control across the globe. Most notably, quarantine and mandatory COVID-19 vaccination for international travellers. Together with a decreased willingness to travel, the implementation of biosecurity measures has had a negative economic and social impact on the travel industry.[110]

Slow travel increased in popularity during the pandemic, with tourists visiting fewer destinations during their trips.[111][112]

Biosecurity measures such as restrictions on cross-border travel, the introduction of mandatory vaccination for international travellers, and the adoption of quarantine or mandatory testing measures have helped to contain the spread of COVID-19.[113] While test-based border screening measures may prove effective under certain circumstances, they may fail to detect a significant quantity

positive cases if only conducted upon arrival without follow-up. A minimum 10-day quarantine may be beneficial in preventing the spread of COVID-19 and may be more effective if combined with an additional control measure like border screening.[113] A study in Science found that travel restrictions could delay the initial arrival of COVID-19 in a country, but that they produced only

modest overall effects unless combined with domestic infection prevention and control measures to considerably reduce transmissions.[114] (This is consistent with prior research on influenza and other communicable diseases.[115][116]) Travel bans early in the pandemic were most effective for isolated locations, such as small island nations.[116]

During the COVID-19 pandemic, many jurisdictions across the globe introduced biosecurity measures on internal borders. This ranged from quarantine measures imposed upon individuals crossing state lines within America to prohibitions on interstate travel in Australia.

Customs

Main article: Customs

North Korean customs officer at Pyongyang Sunan International Airport.

Southern edge (customs border) of Captain Cook wharf, Ports of Auckland, New Zealand. An electric fence is faintly visible behind the historical fence

Each country has its own laws and regulations for the import and export of goods into and out of a country, which its customs authority enforces. The import or export of some goods may be restricted or forbidden, in which case customs controls enforce such policies.[117] Customs enforcement at borders can also entail collecting excise tax and preventing the smuggling of dangerous or

illegal goods. A customs duty is a tariff or tax on the importation (usually) or exportation (unusually) of goods.

In many countries, border controls for arriving passengers at many international airports and some road crossings are separated into red and green channels in order to prioritise customs enforcement.[118][119] Within the European Union's common customs area, airports may operate additional blue channels for passengers arriving from within that area. For such passengers, border control

may focus specifically on prohibited items and other goods that are not covered by the common policy. Luggage tags for checked luggage travelling within the EU are green-edged so they may be identified.[120][121] In most EU member states, travellers coming from other EU countries within the Schengen Area can use the green lane, although airports outside the Schengen Area or with frequent

flights arriving from jurisdictions within Schengen but outside the European Union may use blue channels for convenience and efficiency.

Customs area

A customs area is an area designated for storage of commercial goods that have not cleared border controls for customs purposes. It is surrounded by a customs border. Commercial goods not yet cleared through customs are often stored in a type of customs area known as a bonded warehouse, until processed or re-exported.[122][123] Ports authorised to handle international cargo generally

include recognised bonded warehouses.

For the purpose of customs duties, goods within the customs area are treated as being outside the country. This allows easy transshipment to a third country without customs authorities being involved.[122] For this reason, customs areas are usually carefully controlled and fenced to prevent smuggling. However, the area is still territorially part of the country, so the goods within the

area are subject to other local laws (for example drug laws and biosecurity regulations), and thus may be searched, impounded or turned back.

The term is also sometimes used to define an area (usually composed of several countries) which form a customs union, a customs territory, or to describe the area at airports and ports where travellers are checked through customs.

Sanitary and phytosanitary measures

Main article: Agreement on the Application of Sanitary and Phytosanitary Measures

Sanitary and phytosanitary (SPS) measures are customs measures to protect humans, animals, and plants from diseases, pests, or contaminants. The Agreement on the Application of Sanitary and Phytosanitary Measures is one of the final documents approved at the conclusion of the Uruguay Round of the Multilateral Trade Negotiations. It applies to all sanitary (relating to animals) and

phytosanitary (relating to plants) (SPS) measures that may have a direct or indirect impact on international trade. The SPS agreement includes a series of understandings (trade disciplines) on how SPS measures will be established and used by countries when they establish, revise, or apply their domestic laws and regulations. Per the agreement, states agree to base their SPS standards on

science, and as guidance for their actions, the agreement encourages countries to use standards set by international standard setting organisations. The SPS agreement seeks to ensure that SPS measures will not arbitrarily or unjustifiably discriminate against trade of certain other members nor be used to disguise trade restrictions. Per the agreement, countries maintain the sovereign

right to provide the level of health protection they deem appropriate, but agree that this right will not be misused for protectionist purposes nor result in unnecessary trade barriers. A rule of equivalency rather than equality applies to the use of SPS measures.

The 2012 classification of non-tariff measures (NTMs) developed by the Multi-Agency Support Team (MAST), a working group of eight international organisations, classifies SPS measures as one of 16 non-tariff measure (NTM) chapters. In this classification, SPS measures are classified as chapter A and defined as "Measures that are applied to protect human or animal life from risks arising

from additives, contaminants, toxins or disease-causing organisms in their food; to protect human life from plant- or animal-carried diseases; to protect animal or plant life from pests, diseases, or disease-causing organisms; to prevent or limit other damage to a country from the entry, establishment or spread of pests; and to protect biodiversity".[124] Examples of SPS are tolerance

limits for residues, restricted use of substances, labelling requirements related to food safety, hygienic requirements and quarantine requirements.

In certain countries, sanitary and phytosanitary measures focuses extensively on curtailing and regulating the import of foreign agricultural products in order to protect domestic ecosystems. For example, Australian border controls restrict most (if not all) food products, certain wooden products and other similar items.[125][126][127] Similar restrictions exist in Canada, America and

New Zealand.

Duty-free shops

Duty Free Shop at Pyongyang Sunan International Airport

Main article: Duty-free shop

Common at international airports and occasionally at seaports or land crossings, duty-free shops sell products tax-free to customers who have cleared exit border controls prior to boarding an international flight and, in some airports, to passengers arriving from overseas. Most countries impose limits on how much of each type of duty-free goods, may be purchased by each passenger. The

airport with the most duty-free sales is Seoul Incheon Airport with US$1.85 billion in 2016.[128] Dubai International Airport is second, recording transactions worth $1.82 billion in 2016.[129]

Air and maritime borders

In addition to land borders, countries also apply border control measures to airspace and waters under their jurisdiction. Such measures control access to air and maritime territory as well as extractible resources (e.g. fish, minerals, fossil fuels).

Under the United Nations Convention on the Law of the Sea (UNCLOS)[130], states exercise varying degrees of control over different categories of territorial waters:

Internal waters: Waters landward of the baseline[v], over which the state has complete sovereignty: not even innocent passage[w] is allowed without explicit permission from said state. Lakes and rivers are considered internal waters.

Territorial sea: A state's territorial sea is a belt of coastal waters extending at most 22 kilometres from the baseline[v] of a coastal state. If this would overlap with another state's territorial sea, the border is taken as the median point between the states' baselines, unless the states in question agree otherwise. A state can also choose to claim a smaller territorial sea. The

territorial sea is regarded as the sovereign territory of the state, although foreign ships (military and civilian) are allowed innocent passage through it, or transit passage for straits; this sovereignty also extends to the airspace over and seabed below. As a result of UNCLOS, states exercise a similar degree of control over its territorial sea as over land territory and may thus

utilise coast guard and naval patrols to enforce border control measures provided they do not prevent innocent or transit passage.

Contiguous zone: A state's contiguous zone is a band of water extending farther from the outer edge of the territorial sea to up to 44 kilometres from the baseline, within which a state can implement limited border control measures for the purpose of preventing or punishing "infringement of its customs, fiscal, immigration or sanitary laws and regulations within its territory or

territorial sea". This will typically be 22 kilometres wide, but could be more (if a state has chosen to claim a territorial sea of less than 22 kilometres), or less, if it would otherwise overlap another state's contiguous zone. However, unlike the territorial sea, there is no standard rule for resolving such conflicts and the states in question must negotiate their own compromise. The

United States invoked a contiguous zone out to 44 kilometres from the baseline on 29 September 1999.[131]

Exclusive economic zone An exclusive economic zone extends from the baseline[v] to a maximum of 370 kilometres. A coastal nation has control of all economic resources within its exclusive economic zone, including fishing, mining, oil exploration, and any pollution of those resources. However, it cannot prohibit passage or loitering above, on, or under the surface of the sea that is in

compliance with the laws and regulations adopted by the coastal State in accordance with the provisions of the UN Convention, within that portion of its exclusive economic zone beyond its territorial sea. The only authority a state has over its EEZ is therefore its ability to regulate the extraction or spoliation of resources contained therein and border control measures implemented to

this effect focus on the suppression of unauthorised commercial activity.

Vessels not complying with a state's maritime policies may be subject to ship arrest and enforcement action by the state's authorities. Maritime border control measures are controversial in the context of international trade disputes, as was the case following France's detention of British fishermen in October 2021 in the aftermath of Brexit[132][133] or when the Indonesian navy detained

the crew of the Seven Seas Conqueress alleging that the vessel was unlawfully fishing within Indonesian territorial waters while the Singaporean government claimed the vessel was in Singaporean waters near Pedra Branca.[134]

Similarly, international law accords each state control over the airspace above its land territory, internal waters, and territorial sea. Consequently, states have the authority to regulate flyover rights and tax foreign aircraft utilising their airspace. Additionally, the International Civil Aviation Organisation designates states to administer international airspace, including airspace

over waters not forming part of any state's territorial sea. Aircraft unlawfully entering a country's airspace may be grounded and their crews may be detained.

Many countries implement air defence identification zones (ADIZs) requiring aircraft approaching within a specified distance of its airspace to contact or seek prior authorisation from its military or transport authorities.[135] An ADIZ may extend beyond a country's territory to give the country more time to respond to possibly hostile aircraft.[136] The concept of an ADIZ is not defined

in any international treaty and is not regulated by any international body,[136][137] but is nevertheless a well-established aerial border control measure.[x] Usually such zones only cover undisputed territory, do not apply to foreign aircraft not intending to enter territorial airspace, and do not overlap.[137][140]

Border security

The border fence built by India, as seen from near the Hili border station on the Bangladeshi side.

Border security measures are measures taken by a country or group of countries to enforce its border control policies.[141] Such measures target a variety of issues, ranging from customs violations and trade in unlawful goods to the suppression of unauthorised migration or travel. The specific border security measures taken by a jurisdiction vary depending on the priorities of local

authorities and are affected by social, economic, and geographical factors.

In India, which maintains free movement with Nepal and Bhutan, border security focuses primarily on the Bangladeshi, Pakistani, and Myanmar borders. In order to deter unlawful immigration and drug trafficking from Bangladesh,[142] India is constructing the India-Bangladesh barrier. On the Pakistani border, the Border Security Force aims to prevent the infiltration of Indian territory by

terrorists from Pakistan and other countries in the west (Afghanistan, Iraq, Syria, etc.). In contrast, India's border with Myanmar is porous and the 2021 military coup in Myanmar saw an influx of refugees seeking asylum in border states including Mizoram.[143] The refoulement of Rohingya refugees is a contentious aspect of India's border control policy vis à vis Myanmar.[144]

Mexico–United States barrier in California

United States border security policy is largely centred on the country's border with Mexico. Security along this border is composed of many distinct elements; including physical barriers, patrol routes, lighting, and border patrol personnel. Former president Donald Trump's proposal to build a new wall along the border formed a major feature of his 2016 presidential campaign and, over the

course of his presidency, his administration spent approximately US$15 billion on the project, with US$5 billion appropriated from US Customs and Border Protection, US$6.3 billion appropriated from anti-narcotics initiative funded by congress, and US$3.6 billion appropriated from the American military.[145] Members of both the Democratic Republican parties who opposed President Trump's

border control policies, regarded the border wall as unnecessary or undesirable, arguing that other measures would be more effective at reducing illegal immigration than building a wall, including tackling the economic issues that lead to immigration being a relevant issue altogether, border surveillance or an increase in the number of customs agents.[146]

Similar to India's barrier with Bangladesh and the proposed wall between America and Mexico, Iran has constructed a wall on its frontier with Pakistan. The wall aims to reduce unauthorised border crossings[147] and stem the flow of drugs,[148] and is also a response to terrorist attacks, notably the one in the Iranian border town of Zahedan on 17 February 2007, which killed thirteen

people, including nine Iranian Revolutionary Guard officials.[149]

Hungarian border barrier with Serbia

Border security has, over the first two decades of the century, also become a major concern in the Schengen Area, specifically as a result of the European migrant crisis. The walls at Melilla and at Ceuta on Spain's border with Morocco are a part of the trend towards increasing border security in response to an unprecedented rise in both refugees and economic migrants from countries in

Sub Saharan Africa. Similar, though less drastic, measures have been taken on the Schengen area's borders with Turkey in response to the refugee crisis created in Syria by terrorist organisations such as Daesh and the Syrian Free Army. The creation of European Union's collective border security organisation, Frontex, is another aspect of the bloc's growing focus on border security.

Within the Schengen Area, border security has become an especially prominent priority for the Hungarian government under right-wing strongman[150][151] Viktor Orbán. Hungary completed the construction of 175 kilometres of fencing between with Serbia in September 2015 and on the border with Croatia in October 2015 to stop unauthorised border crossings.[152] In April 2016, Hungarian

government announced construction of reinforcements of the barrier, which it described as "temporary".[153] In July 2016, nearly 1,300 migrants were "stuck" on the Serbian side of the border.[154] In August 2016, Orbán announced that Hungary will build another larger barrier on its southern border.[155] On 28 April 2017, the Hungarian government announced it had completed a second

fence, 155 kilometres long with Serbia.[156][157] On 24 September 2015, Hungary began building fence on its border with Slovenia, in the area around Tornyiszentmiklós–Pince border crossing.[158] The razor wire obstacle was removed two days later.[159] As of March 2016, everything is in place if Hungary decides to build a border barrier on the Hungarian–Romanian border – the

military is "only waiting for the command from the government".[160]

Another example of border security is the Israeli anti-tunnel barrier along its border with the Gaza Strip, a part of the State of Palestine under the control of Hamas (a militant group backed by the Muslim Brotherhood, a Qatari-sponsored militant group). In order to curtail Hamas's ability to build tunnels into Israeli-controlled territory, Israel have built a slurry wall. Similarly,

Saudi Arabia has begun construction of a border barrier or fence between its territory and Yemen to prevent the unauthorized movement of people and goods. The difference between the countries' economic situations means that many Yemenis head to Saudi Arabia to find work. Saudi Arabia does not have a barrier with its other neighbours in the Gulf Cooperation Council, whose economies are

more similar. In 2006 Saudi Arabia proposed constructing a security fence along the entire length of its 900 kilometre long desert border with Iraq in a multimillion-dollar project to secure the Kingdom's borders in order to improve internal security, control illegal immigration, and bolster its defences against external threats.[161] As of July 2009 it was reported that Saudis will pay

$3.5 billion for security fence.[162] The combined wall and ditch will be 965 kilometres long and include five layers of fencing, watch towers, night-vision cameras, and radar cameras and manned by 30,000 troops.[163] Elsewhere in Europe, the Republic of Macedonia began erecting a fence on its border with Greece in November 2015.[164] On the land border between Palestine and the portion

of the Sinai peninsula administered by the African nation of Egypt, the latter began construction of a border barrier in 2009 prompted by concern that militant organisations were making use of the Gaza Strip smuggling tunnels to move weapons and personnel between Gaza and Egypt.[165]

In 2003, Botswana began building a 480 kilometre long electric fence along its border with Zimbabwe. The official reason for the fence is to stop the spread of foot-and-mouth disease among livestock. Zimbabweans argue that the height of the fence is clearly intended to keep out people. Botswana has responded that the fence is designed to keep out cattle, and to ensure that entrants have

their shoes disinfected at legal border crossings. Botswana also argued that the government continues to encourage legal movement into the country. Zimbabwe was unconvinced, and the barrier remains a source of tension.[166]

Border checkpoints

Main articles: Border checkpoint, Port of entry, and International airport

Sultan Iskandar Building, Johor Bahru, Malaysia

Sultan Iskandar Building

Woodlands Checkpoint, Singapore

Woodlands Checkpoint

The Sultan Iskandar Building (Malaysia) and Woodlands Checkpoint (Singapore) on the Malaysia–Singapore border handles the busiest international land border crossing in the world, with 350,000 travellers daily prior to the COVID-19 pandemic.[167][168]

The International Terminal at San Francisco International Airport is an airport of entry for travellers entering America and has border checkpoint facilities for arriving passengers. Like most North American airports, it does not have a sterile international transit area. Domestic and international passengers are thus not clearly separated. This enables easier transfers from domestic to

international flights but requires international transit passengers to clear the border checkpoint even if their final destination is outside America.

A Border checkpoint is a place where goods or individuals moving across borders are inspected for compliance with border control measures. Access-controlled borders often have a limited number of checkpoints where they can be crossed without legal sanctions. Arrangements or treaties may be formed to allow or mandate less restrained crossings (e.g. the Schengen Agreement). Land border

checkpoints (land ports of entry) can be contrasted with the customs and immigration facilities at seaports, international airports, and other ports of entry.

Checkpoints generally serve two purposes:

To prevent entrance of individuals who are either undesirable (e.g. criminals or others who pose threats) or simply unauthorised to enter.

To prevent entrance of goods that are illegal or subject to restriction, or to collect tariffs in accordance with customs or quarantine policies.

Port of entry

A border checkpoint at which travellers are permitted to enter a jurisdiction is known as a port of entry. International airports are usually ports of entry, as are road and rail crossings on a land border. Seaports can be used as ports of entry only if a dedicated customs presence is posted there. The choice of whether to become a port of entry is up to the civil authority controlling

the port.

An airport of entry is an airport that provides customs and immigration services for incoming flights. These services allow the airport to serve as an initial port of entry for foreign visitors arriving in a country. While the terms airport of entry and international airport are generally used interchangeably, not all international airports qualify as airports of entry since

international airports without any immigration or customs facilities exist in the Schengen Area whose members have eliminated border controls with each other. Airports of entry are usually larger than domestic airports and often feature longer runways and facilities to accommodate the heavier aircraft commonly used for international and intercontinental travel. International airports

often also host domestic flights, which often help feed both passengers and cargo into international ones (and vice-versa). Buildings, operations and management have become increasingly sophisticated since the mid-20th century, when international airports began to provide infrastructure for international civilian flights. Detailed technical standards have been developed to ensure safety

and common coding systems implemented to provide global consistency. The physical structures that serve millions of individual passengers and flights are among the most complex and interconnected in the world. By the second decade of the 21st century, there were over 1,200 international airports and almost two billion international passengers along with 50 million tonnes of cargo passing

through them annually.

In order to exempt passengers transitting between international flights from clearing border checkpoints, most international airports outside North America feature a "sterile lounge", an area after security checkpoints within which passengers are free to move freely and which is generally deemed to be outside the immigration and customs area of the country in which the airport situated.

In addition to employees, only processed passengers with a valid ticket are allowed inside the sterile lounge.[169]

Sterile lounge at Changi Airport Terminal 3 in Singapore. Passengers transitting between international flights at Terminals 1, 2, and 3 of Changi Airport disembark directly into the sterile lounge, may proceed to their connecting gate without clearing the border checkpoint or completing any other border control formality, and can move between the sterile lounge areas of each terminal

using the Skytrain without passing through any checkpoint.

A port of entry at Shir Khan Bandar in northern Afghanistan near the Tajikistan border guarded by American military personnel prior to their withdrawal from Afghanistan, following which the Taliban assumed control over border checkpoints between Afghanistan and its neighbours.

The Hong Kong–Macau Ferry Terminal in Sheung Wan is a sea port of entry to Hong Kong and an example of an internal border checkpoint where travellers arriving from or departing for other cities in the Pearl River Delta are subjected to border control measures.

The cruise-ship pier at Ocean Terminal is also a sea port of entry to Hong Kong. While the HK-Macau Ferry Terminal serves as a port of entry for travellers from other Chinese cities in the Pearl River Delta, the Ocean Terminal serves as a port of entry for visitors arriving via cruise ship from a wider variety of jurisdictions.

Quilantan entry

A 'Quilantan' or 'Wave Through' entry is a phenomenon at American border checkpoints authorising a form of non-standard but legal entry without any inspection of travel documents. It occurs when the border security personnel present at a border crossing choose to summarily admit some number of persons without performing a standard interview or document examination.[170]

Typically this can occur when an official border crossing is busy and an immigration officer waves a car through without first checking all passengers for their travel documents. If an individual can prove that they were waved through immigration in this manner, then they are considered to have entered with inspection despite not having answered any questions or received a passport entry

stamp.[171]

This definition of legal entry does not apply to situations where foreigners entered America but have not crossed at a legal, manned border station. Thus it does not provide a path to legal residency for those who have entered America by crossing accidental gaps in the borders around geological formations.[172]

Border zones

Border zones are areas near borders that have special restrictions on movement. Governments may forbid unauthorised entry to or exit from border zones and restrict property ownership in the area. The zones function as buffer zones specifically monitored by border patrols in order to prevent unauthorised cross-border travel. Border zones enable authorities to detain and prosecute

individuals suspected of being or aiding undocumented migrants, smugglers, or spies without necessarily having to prove that the individuals in question actually engaged in the suspected unauthorised activity since, as all unauthorised presence in the area is forbidden, the mere presence of an individual permits authorities to arrest them. Border zones between hostile states can be

heavily militarised, with minefields, barbed wire, and watchtowers. Some border zones are designed to prevent illegal immigration or emigration and do not have many restrictions but may operate checkpoints to check immigration status. In most places, a border vista is usually included and/or required. In some nations, movement inside a border zone without a licence is an offence and will

result in arrest. No probable cause is required as mere presence inside the zone is an offence, if it is intentional.[173] Even with a licence to enter, photography, making fires, and carrying of firearms and hunting are prohibited.

Examples of international border zones are the Border Security Zone of Russia and the Finnish border zone on the Finnish–Russian border. There are also intra-country zones such as the Cactus Curtain surrounding the Guantanamo Bay Naval Base in Cuba, the Korean Demilitarised Zone along the North Korea-South Korea demarcation line and the Frontier Closed Area in Hong Kong. Important

historical examples are the Wire of Death set up by the German Empire to control the Belgium–Netherlands border and the Iron Curtain, a set of border zones maintained by the Soviet Union and its satellite states along their borders with Western states. One of the most militarised parts was the restricted zone of the inner German border. While initially and officially the zone was for

border security, eventually it was engineered to prevent escape from the Soviet sphere into the West. Ultimately, the Eastern Bloc governments resorted to using lethal countermeasures against those trying to cross the border, such as mined fences and orders to shoot anyone trying to cross into the West. The restrictions on building and habitation made the area a "green corridor", today

established as the European Green Belt.

In the area stretching inwards from its internal border with the mainland, Hong Kong maintains a Frontier Closed Area out of bounds to those without special authorisation. The area was established in the 1950s when Hong Kong was under British administration as a consequence of the Convention for the Extension of Hong Kong Territory prior to the Transfer of sovereignty over Hong Kong in

1997. The purposes of the area were to prevent illegal immigration and smuggling; smuggling had become prevalent as a consequence of the Korean War. Today, under the one country, two systems policy, the area continues to be used to curtail unauthorised migration to Hong Kong and the smuggling of goods in either direction.

As a result of the partition of the Korean peninsula by America and the Soviet Union after World War II, and exacerbated by the subsequent Korean War, there is a Demilitarised Zone (DMZ) spanning the de facto border between North and South Korea. The DMZ follows the effective boundaries as of the end of the Korean War in 1953. Similarly to the Frontier Closed Area in Hong Kong, this zone

and the defence apparatus that exists on both sides of the border serve to curtail unauthorised passage between the two sides.

In South Korea, there is an additional fenced-off area between the Civilian Control Line (CCL) and the start of the Demilitarised Zone. The CCL is a line that designates an additional buffer zone to the Demilitarised Zone within a distance of 5 to 20 kilometres from the Southern Limit Line of the Demilitarised Zone. Its purpose is to limit and control the entrance of civilians into the

area in order to protect and maintain the security of military facilities and operations near the Demilitarised Zone. The commander of the 8th US Army ordered the creation of the CCL and it was activated and first became effective in February 1954.[174] The buffer zone that falls south of the Southern Limit Line is called the Civilian Control Zone. Barbed wire fences and manned military

guard posts mark the CCLe. South Korean soldiers typically accompany tourist busses and cars travelling north of the CCL as armed guards to monitor the civilians as well as to protect them from North Korean intruders. Most of the tourist and media photos of the "Demilitarised Zone fence" are actually photos of the CCL fence. The actual Demilitarised Zone fence on the Southern Limit Line

is completely off-limits to everybody except soldiers and it is illegal to take pictures of the Demilitarised Zone fence.

Some border zones, referred to as border vistas, are composed of legally mandated cleared space between two areas of foliage located at an international border intended to provide a clear demarcation line between two jurisdictions. Border vistas are most commonly found along undefended international boundary lines, where border security is not as much of a necessity and a built barrier

is undesired, and are a treaty requirement for certain borders. An example of a border vista is a six-metre cleared space around unguarded portions of the Canada–United States border.[175] Similar clearings along the border line are provided for by many international treaties. For example, the 2006 border management treaty between Russia and China provides for a 15-metre cleared strip

along the two nations' border.[176]

The border vista along the Canada–United States border, as seen from a wayside on the Alaska Highway.

Control Line, Imjingak, Paju, South Korea

A South Korean checkpoint at the Civilian Control Line, located outside of the Demilitarised Zone

Korean Demilitarised Zone as seen from the North

Frontier Closed Area signboard at Lo Wu

Border zone in Brest with a security electric fence, a ploughed trace-control strip and a pillbox.

Border zone marked on a tree on the Finland–Russia border: no entry.

Drugs

Singapore arrival card warning visitors about the death penalty for drug trafficking.

Border control in many Asian countries prioritise mitigating trade in narcotics. For instance, Singapore, Malaysia, Thailand, and Indonesia impose mandatory death sentences on individuals caught smuggling restricted substances across their borders. For example, Muhammad Ridzuan Ali was executed in Singapore on 19 May 2017 for drug trafficking.[177] India and Malaysia are focusing

resources on eliminating drug smuggling from Myanmar and Thailand respectively. The issue stems largely from the high output of dangerous and illegal drugs in the Golden Triangle as well as in regions further west such as Afghanistan.

A similar problem exists east of the Pacific, and has resulted in countries such as Mexico and America tightening border control in response to the northward flow of illegal substances from regions such as Colombia. The Mexican Drug War and similar cartel activity in neighbouring areas has exacerbated the problem.

Immigration law and policy

Main article: Immigration law

Immigration law refers to the national statutes, regulations, and legal precedents governing immigration into and deportation from a country. Strictly speaking, it is distinct from other matters such as naturalisation and citizenship, although they are often conflated. Immigration laws vary around the world, as well as according to the social and political climate of the times, as

acceptance of immigrants sways from the widely inclusive to the deeply nationalist and isolationist. Countries frequently maintain laws which regulate both the rights of entry and exit as well as internal rights, such as the duration of stay, freedom of movement, and the right to participate in commerce or government. National laws regarding the immigration of citizens of that country

are regulated by international law. While the United Nations' International Covenant on Civil and Political Rights mandates[178] that all countries allow entry to their own citizens, this principle is not always respected in practice. For instance, during the COVID-19 pandemic, Australia adopted a policy of denying entry to all individuals in particularly affected jurisdictions,

including Australian citizens and permanent residents.[179][180] Similarly, while states within the Schengen Area typically permit freedom of movement across borders, many states within the area implemented ad hoc border controls during the pandemic.

Immigration policy is the aspect of border control concerning the transit of people into a country, especially those that intend to stay and work in the country. Taxation, tariff and trade rules set out what goods immigrants may bring with them, and what services they may perform while temporarily in the country. Investment policy sometimes permits wealthy immigrants to invest in

businesses in exchange for favourable treatment and eventual naturalisation. Agricultural policy may make exemptions for migrant farm workers, who typically enter a country only for the harvest season and then return home to a country or region in the Global South (such as Mexico or Jamaica from where America and Canada, respectively, often import temporary agricultural labour).[181] An

important aspect of immigration policy is the treatment of refugees,[182] more or less helpless or stateless people who throw themselves on the mercy of the state they try to enter, seeking refuge from actual or purported poor treatment in their country of origin. Asylum is sometimes granted to those who face persecution or a well-founded fear of persecution on account of race, religion,

nationality, membership of a particular social group, or political opinion.

Diaspora communities

An OCI booklet exempting its bearer from usual immigration controls in India.

Karta Polaka – specimen document

Certain countries adopt immigration policies designed to be favourable towards members of diaspora communities with a connection to the country. For example, the Indian government confers Overseas Citizenship of India (OCI) status on foreign citizens of Indian origin to live and work indefinitely in India. OCI status was introduced in response to demands for dual citizenship by the

Indian diaspora, particularly in countries with large populations of Indian origin. It was introduced by The Citizenship (Amendment) Act, 2005 in August 2005.[183][184] In the ASEAN region, a large portion of the Singaporean, Malaysian, and Bruneian population hold OCI status. Large OCI communities also exist in North America, the United Kingdom, Australia, and New Zealand, as well as in

many African nations (particularly South Africa, Madagascar, and members of the East African Community). OCI status exempts holders from immigration controls generally imposed upon others of the same nationality.

Similarly, Poland issues the Karta Polaka to citizens of certain northeast European countries with Polish ancestry.

A British Ancestry visa is a document issued by the United Kingdom to Commonwealth citizens with a grandparent born in the United Kingdom, Channel Islands or Isle of Man who wish to work in the United Kingdom. Similar to OCI status, it exempts members of the country's diaspora from usual immigration controls. It is used mainly by Australians, New Zealanders, Canadians, and South Africans

of British descent working or studying in the United Kingdom.[185]

Some nations recognise a right of return for people with ancestry in that country or a connection to a particular ethnic group. A notable example of this is the right of Sephardi Jews to acquire Spanish nationality by virtue of their community's Spanish origins. Similar exemptions to immigration controls exist for people of Armenian origin seeking to acquire Armenian citizenship. Ghana,

similarly, grants an indefinite right to stay in Ghana to members of the African diaspora regardless of citizenship.[186] Similarly, Israel maintains a policy permitting members of the Jewish diaspora to immigrate to Israel regardless of prior nationality.

South Korean immigration policy is relatively unique in that, as a consequence of its claim over the territory currently administered by North Korea, citizens of North Korea are regarded by the South as its own citizens by birth.[187] Consequently, North Korean refugees in China often attempt to travel to countries such as Thailand which, while not offering asylum to North Koreans,

classifies them as unauthorised immigrants and deports them to South Korea instead of North Korea.[188][189][190] At the same time, this policy has operated to prevent pro-North Korea Zainichi Koreans recognised by Japan as Chōsen-seki from entering South Korea without special permission from the South Korean authorities as, despite being regarded as citizens of the Republic of Korea

and members of the Korean diaspora, they generally refuse to exercise that status.[191]

Special immigration areas

In various special immigration areas around the world, border control policies can range from severely limiting migration, as in Greece's Mount Athos, to allowing most types of migration, such as the free migration[y] policy in force in Svalbard. Similar policies are in force for Iran's Kish and Qeshm islands, and for Iraqi Kurdistan.

Local border traffic

The front of the updated version of the Border Crossing Card issued to Mexican nationals

Local border traffic or small border traffic is the flow of travellers within the area surrounding a controlled international or internal border. In many cases local border traffic is subject to bilateral regulation aimed at the simplification of border crossing for individuals travelling within a designated area surrounding the border.[193] In certain cases, this entails adopting border

control policies imposing reduced border controls for frequent travellers intending to remain within a border area. Depending on the particular border in question, these measures may be restricted to local residents, implemented as a blanket regional visa waiver by one jurisdiction for nationals of the other, or available to individuals lawfully present in one jurisdiction seeking to

visit the other.

For example, the relaxed border controls maintained by Bhutan for those not proceeding past Phuentsholing and certain other border cities enable travellers to enter without going through any document check whatsoever. The Border Crossing Card issued by American authorities to Mexican nationals enables Mexicans to enter border areas without a passport.[z] Both America and Bhutan maintain

interior checkposts to enforce compliance.

China maintains relaxed border controls for individuals lawfully in Hong Kong or Macau to visit the surrounding Pearl River Delta visa-free, provided that the following conditions are met:[196]

The visitor is a national of a country which has diplomatic relations with the People's Republic of China

The visitor is visiting the Pearl River Delta as part of a tour group organised by a Hong Kong or Macau based travel agency

The stay is for six days or less

The visitor stays only within the cities of Guangzhou, Shenzhen, Zhuhai, Foshan, Dongguan, Zhongshan, Jiangmen, Zhaoqing, Huizhou and Shantou.

In Belarus, the "Brest – Grodno" visa free territory, established by a presidential decree signed in August 2019 has permitted local visa free access to most visitors lawfully present in the neighbouring Schengen Area since 10 November 2019.[197][198] Visitors are allowed to stay without a visa for 15 days. Entry is possible through the following checkpoints with Poland and Lithuania -

Brest (Terespol), Bruzgi (Kuźnica), Damačava (Sławatycze), Bieniakoni (Šalčininkai), Bierastavica (Bobrowniki), Piasčatka (Połowce), Pryvalka (Raigardas), Piareraŭ (Białowieża), Liasnaja (Rudawka), Pryvalka (Švendubrė), Brest-Uschodni Railway Station, Grodno Railway Station, Brest Airport and Grodno Airport. Prior to travel, visitors must obtain an appropriate document[199]

issued by a local travel agency registered in Belarus.

Similarly, Schengen states which share an external land border with a non-Schengen state are authorised by virtue of the EU Regulation 1931/2006 to conclude or maintain bilateral agreements with neighbouring third countries for the purpose of implementing a unilateral or reciprocal local border traffic regime.[200] Such agreements define a border area on either side of the border, and

provide for the issuance of local border traffic permits to residents of the border area. Permits may be used to cross the EU external border within the border area, are not stamped on crossing the border and must display the holder's name and photograph, as well as a statement that its holder is not authorised to move outside the border area and that any abuse shall be subject to

penalties.

Often, additional border crossing points are created to carry only local border traffic.

Immigrant investor programmes

Immigrant investor programmes are border control policies that offer permanent residence or citizenship in return for investment.[201][202][203] Immigrant investor programmes originated in the 1980s when tax havens in the Pacific and Caribbean began "cash-for-passport" programmes that facilitated visa-free travel and tax avoidance.[204] Such programmes have sparked controversy in several

countries. A lack of demonstrable economic benefits, and security concerns, have been among the most common criticisms. In 2014 the Canadian government suspended their golden visa programme (although, as of 2017, Quebec maintains its own golden visa programme).[205] The implementation of such programmes in Europe has been criticised by the European Parliament,[206] which approved a

non-binding resolution that in 2014 declaring that an EU passport, which by definition provides its bearer the right to reside in any EU or EEA jurisdiction, should not have a "price tag".[207]

Open borders

Main article: Open border

An open border is the deregulation and or lack of regulation on the movement of persons between nations and jurisdictions, this does not apply to trade or movement between privately owned land areas.[208] Most nations have open borders for travel within their nation of travel, though more authoritarian states may limit the freedom of internal movement of its citizens, as for example in

the former USSR. However, only a handful of nations have deregulated open borders with other nations, an example of this being European countries under the Schengen Agreement or the open Belarus-Russia border.[209] Open borders used to be very common among all nations, however this became less common after the First World War, which led to the regulation of open borders, making them less

common and no longer feasible for most industrialised nations.[210]

Open borders are the norm for borders between subdivisions within the boundaries of sovereign states, though some countries do maintain internal border controls (for example between the People's Republic of China mainland and the special administrative regions of Hong Kong and Macau, or between the United States and the unincorporated territories of Guam, the Northern Marianas and

American Samoa, and the Minor Outlying Islands). Open borders are also usual between member states of federations, though (very rarely) movement between member states may be controlled in exceptional circumstances.[aa] Federations, confederations and similar multi-national unions typically maintain external border controls through a collective border control system, though they sometimes

have open borders with other non-member states through special international agreements – such as between Schengen Agreement countries as mentioned above.

Presently, open border agreements of various types are in force in several areas around the world, as outlined below:

Asia and Oceania:

Under the 1950 Indo-Nepal Treaty of Peace and Friendship, India and Nepal maintain a similar arrangement to the CTA and the Union State. Indians and Nepalis are not subject to any migration controls in each other's countries and there are few controls on land travel by citizens across the border.

India and Bhutan also have a similar programme in place The border between Jaigaon, in the Indian state of West Bengal, and the city of Phuentsholing is essentially open, and although there are internal checkpoints, Indians (as outlined under the Visa policy of Bhutan are allowed to proceed throughout Bhutan with a voter's ID or an identity slip from the Indian consulate in

Phuentsholing. Similarly, Bhutanese passport holders enjoy free movement in India.

Thailand and Cambodia: Whilst not as liberal as the policies concerning the Indo-Nepalese and Indo-Bhutanese borders, Thailand and Cambodia have begun issuing combined visas to certain categories of tourists applying at specific Thai or Cambodian embassies and consulates in order to enable freer border crossings between the two countries.[211] The policy is currently in force for

nationals of America and several European (primarily EU, EEA, and GCC) and Oceanian countries as well as for Indian and Chinese nationals residing in Singapore.[212]

Australia and New Zealand: Similar to the agreement between India and Nepal, Trans-Tasman Travel Arrangement between Australia and New Zealand is a free movement agreement citizens of each country to travel freely between them and allowing citizens and some permanent residents to reside, visit, work, study in the other country for an indefinite period, with some restrictions.[213][214]

The arrangement came into effect in 1973, and allows citizens of each country to reside and work in the other country, with some restrictions. Other details of the arrangement have varied over time. From 1 July 1981, all people entering Australia (including New Zealand citizens) have been required to carry a passport. Since 1 September 1994 Australia, has had a universal visa

requirement, and to specifically cater for the continued free movement of New Zealanders to Australia, the Special Category Visa was introduced for New Zealanders.

Central America :The Central America-4 Border Control Agreement abolishes border controls for land travel between El Salvador, Honduras, Nicaragua, and Guatemala. However, this does not apply to air travel.

Europe and the Middle East

Union State of Russia and Belarus The Union State of Russia and Belarus is a supranational union of Russia and Belarus, which eliminates all border controls between the two nations. Before a visa agreement was signed in 2020, each country maintained its own visa policies, thus resulting in non-citizens of the two countries generally being barred from travelling directly between the two.

However, since the visa agreement was signed, each side recognises the other's visas, which means that third-country citizens can enter both countries with a visa from either country.[215]

Western Europe: The two most significant free travel areas in Western Europe are the Schengen Area, in which very little if any border control is generally visible, and the Common Travel Area (CTA), which partially eliminates such controls for nationals of the United Kingdom and Ireland. Between countries in the Schengen Area, and to an extent within the CTA on the British Isles,

internal border control is often virtually unnoticeable, and often only performed by means of random car or train searches in the hinterland, while controls at borders with non-member states may be rather strict.

Gulf Cooperation Council: Members of the Gulf Cooperation Council, or GCC, allow each other's citizens freedom of movement in an arrangement similar to the CTA and to that between India and Nepal. Between 5 June 2017 and 5 January 2021, freedom of movement in Saudi Arabia, the UAE, and Bahrain was suspended for Qataris as a result of the Saudi-led blockade of the country.

A New Zealand visa stamp issued under Trans-Tasman Travel Arrangement on an Australian travel document.

Visa policy of Bhutan, showing the free movement arrangement between India and Bhutan

Visa policy of Nepal, showing free movement between India and Nepal under the 1950 treaty

Irish border at Killeen (within CTA) marked only by a metric speed sign, as the Republic of Ireland uses the metric system whilst British road signs use imperial units

Sign often found at crossings from the Republic of Ireland into the North.

Open Schengen Area border crossing between Germany and the Netherlands

Open Schengen Area border crossing at the France-Monaco border (was open long before Schengen started)

Open Schengen Area border crossing at the Swiss-Lichtenstein border (was open long before Schengen started)

Open Schengen Area border crossing at the Slovenian-Italian border, with abandoned rain shelter.

Two road-signs on the side of an open stretch of a two-lane highway.

A typical Schengen internal border crossing has no border control post and only a common EU-state sign displaying the name of the country being entered, as here between Germany and Austria. The larger blue sign announces entry to the Federal Republic of Germany in German, the smaller white sign announces entry into the German state of Bavaria.

International zones

An international zone is a type of extraterritorial area not fully subject to any country's border control policies. The term most commonly refers to the areas of international airports after border exit controls or before border entry controls. These areas often contain duty-free shopping, but they are not fully extraterritorial. It is usually possible to transfer between flights

without needing either the passport check or visa otherwise needed to enter the country. In areas of conflict there may be international zones called green zones that form protective enclaves to keep diplomats safe. Countries in conflict may also have international zones separating each other. Some of the international zones are subject to international law.

Airport transit areas

The international zone in an international airport is the area where arriving international passengers have not formally entered the country by clearing arrival customs and immigration controls, and departing passengers have formally exited the country by clearing exit immigration control. Transit passengers can usually take connecting international flights in the international zone

without clearing customs and immigration controls, and in most cases do not require a visa.[216][217][218] Some countries, however, require transit passengers of certain nationalities to hold a direct airside transit visa[219] even when they would not need to pass through border controls. In addition, some countries, notably Canada, Russia and South Africa, perform document checks by

border officers in the international transit corridor, for which a visa may (e.g. Canada) or may not (e.g. Russia) be required.

Two major exceptions are America and Canada, where airports typically have no international transit zones. All passengers arriving on international flights are subject to customs and immigration inspections. Nationals of countries other than America and Canada at an American airport requires at least a C-1 transit visa, or ESTA for eligible travellers. Meanwhile, transiting at a Canadian

airport for nationals of countries other than Canada or America generally requires a visa or Electronic Travel Authorisation except for individuals proceeding to or from America who qualify for the China Transit Programme or Transit Without Visa Programme.

A common feature of the international zone is duty-free shopping for departing and transit passengers, and in some cases arriving passengers subject to duty-free allowances.

International zones in airports are fully under the jurisdiction of the country where they are located and local laws apply. Persons caught committing an unlawful act (e.g. possession of contraband such as illegal drugs) in the international zone are liable for prosecution.

Other examples

The United Nations' Headquarters are a series of complexes in New York City (United States), Geneva (Switzerland), Vienna (Austria), and Nairobi (Kenya)[220] that exist on international territories administered by the United Nations, while still subject to most local and national laws.[221]

The whole estuary of the Han River in the Korean Peninsula is deemed a "Neutral Zone" and is officially off-limits to all civilian vessels. Only military vessels are allowed within this neutral zone. According to the July 1953 Korean Armistice Agreement civil shipping was supposed to be permissible in the Han River estuary and allow Seoul to be connected to the Yellow Sea (West Sea) via

the Han River.[222] However, both Koreas and the UNC failed to make this happen. The South Korean government ordered the construction of the Ara Canal to finally connect Seoul to the Yellow Sea, which was completed in 2012. Seoul was effectively landlocked from the ocean until 2012. The biggest limitation of the Ara Canal is it is too narrow to handle any vessels except small tourist

boats and recreational boats, so Seoul still cannot receive large commercial ships or passenger ships in its port. In recent years Chinese fishing vessels have taken advantage of the tense situation in the Han River Estuary Neutral Zone and illegally fished in this area due to both North Korean and South Korean navies never patrolling this area due to the fear of naval battles breaking

out. This has led to firefights and sinkings of boats between Chinese fishermen and South Korean Coast Guard.[223][224] On January 30, 2019, North Korean and South Korean military officials signed a landmark agreement that would open the Han River Estuary to civilian vessels for the first time since the Armistice Agreement in 1953. The agreement was scheduled to take place in April 2019

but the failure of the 2019 Hanoi Summit indefinitely postponed these plans.[225][226][227]

EuroAirport Basel Mulhouse Freiburg is an airport located in France 20 kilometres southeast of Mulhouse and 3.5 kilometres northwest of Basel (Switzerland), to which it is connected by a customs-free road that allows travellers to access the airport through Swiss and not French border control. The airport has been jointly operated by the two countries since a 1946 treaty. Geneva Airport

in Switzerland has a similar French sector.[228][229]

Khmeimim Air Base in Syria is leased to the Russian government for a period of 49 years, with the Russian government having extraterritorial jurisdiction over the air base and its personnel.[230][231]

The Free City of Danzig was an international League of Nations protectorate that contained the Baltic Sea port of Danzig (now Gdańsk, Poland) and nearly 200 surrounding towns and villages that had a predominantly German population. It was created on 15 November 1920[232][233] in accordance with the 1919 Treaty of Versailles that ended World War I, which excluded the area from Weimar

Germany and the new Second Polish Republic.[234] The Free City had a customs union with Poland.

The Tomb of Suleyman Shah, grandfather of the founder of the Ottoman Empire Osman I, has been located in northern Syria since the empire's collapse. The 1921 Treaty of Ankara between Turkey and France (which ruled Syria at the time) states that the tomb "shall remain, with its appurtenances, the property of Turkey, who may appoint guardians for it and may hoist the Turkish flag

there".[235] The tomb was moved in 1973 as the site was to be flooded by the creation of Lake Assad, and in 2015 it was relocated unilaterally by Turkey in response to the Syrian Civil War. The Syrian government denounced the move as incompatible with the 1921 treaty; Turkey plans to move the tomb back to the second site.[236]

During the late Qing dynasty, portions of the Chinese coast were surrendered as Concessions to many Western powers and Japan. Each concession had its own legal regime which privileged the foreign power's citizens over the Chinese majority, and replaced Chinese cultural influences with those of the foreign power.

Central Baghdad has an international zone located in a crook of the Tigris River, housing foreign embassies, military headquarters and key Iraqi government institutions. The official name started as the Green Zone but was later changed to the "International Zone" in June 2004 with the restoration of Iraqi sovereignty.[237][238]

French, British, American and Soviet troops divided Vienna into four zones from 1945 to 1955. A small international zone of the historical city centre was governed in rotation by troops of those countries.

During the Cold War division of Berlin, the Friedrichstraße station was served by West Berlin S-Bahn and U-Bahn trains despite being located entirely in East Berlin. West Berliners could transfer between the S-Bahn, U-Bahn and long-distance trains to the West without passing through East German border control. The station featured an East German government-run Intershop, which sold

duty-free and high-quality items at lower prices compared to the West. The station was also the site of a major border crossing where West Berliners and other travellers with appropriate papers could enter East Germany.

No country has sovereignty over international waters. All states have the freedom of fishing, navigation, overflight, laying cables and pipelines, as well as research. Oceans, seas, and waters outside national jurisdiction are also referred to as the high seas or, in Latin, mare liberum (meaning free sea). The 1958 Convention on the High Seas defined "high seas" to mean "all parts of the

sea that are not included in the territorial sea or in the internal waters of a State" and where "no State may validly purport to subject any part of them to its sovereignty".[239] The convention was used as a foundation for the 1982 United Nations Convention on the Law of the Sea, which recognised Exclusive Economic Zones extending 370 kilometres from the baseline, where coastal States

have sovereign rights to the water column and sea floor as well as to the natural resources found there.[240] Ships sailing the high seas are generally under the jurisdiction of the flag state (if there is one);[241] however, when a ship is involved in certain criminal acts, such as piracy,[242] any nation can exercise jurisdiction under the doctrine of universal jurisdiction.

International waters can be contrasted with internal waters, territorial waters and exclusive economic zones.

The Antarctic Treaty System effectively makes the continent of Antarctica an international demilitarised zone de jure.

Under the 1947 United Nations Partition Plan for Palestine, the city of Jerusalem was supposed to become an international corpus separatum. This was never implemented; the city was the scene of fierce fighting in the 1948 war which culminated in its partition between West Jerusalem (Israel) and East Jerusalem (Jordan). In the 1967 war, East Jerusalem was captured and unilaterally annexed

by Israel, in a move that has not been recognized by the international community. The idea of an international zone in Jerusalem, encompassing at least the highly sensitive Old City, continues to feature in many proposals to resolve the Israeli-Palestinian conflict.

Dejima was an island port near the Japanese city of Nagasaki that was ceded to Dutch administration between 1641 and 1854. During the Edo period, it was Japan's only point of interaction with the outside world. Border controls limited passage of foreign merchants from Dejima to Nagasaki and of Japanese from Nagasaki to Dejima.[243][244]

The United Kingdom and France established "international zones" or "control zones" at both ends of the Channel Tunnel, which crosses underneath the English Channel. British authorities exercise authority within the control zone on the French side, and French authorities exercise authority within the control zone on the UK side, under a system of juxtaposed controls. Violations in the

control zone are treated as if they occurred within the territory of the adjoining state within that zone, and extradition is not required to remove a violator to the operating state for prosecution. Officers of the adjoining state may carry firearms within the control zone.[245]

The Free Territory of Trieste was an international zone around the Adriatic Sea port of Trieste, under direct responsibility of the United Nations Security Council. The area was established on 10 February 1947 by a protocol of the Treaty of Peace with Italy in order to accommodate an ethnically and culturally mixed population in a neutral environment free from the rule of either Italy or

Yugoslavia, which made competing claims on the territory. The Free Territory was de facto given to its two neighbours in 1954 and this was formalised much later by the bilateral Treaty of Osimo of 1975, ratified in 1977.[246] During the late 1940s and in the years following the division of the Territory, up to 40,000 people[247] (mostly Italians) chose to leave the Yugoslav B zone and

move to the A zone or Italy for various reasons: Some were intimidated into leaving, and some simply preferred not to live in Yugoslavia. In Yugoslavia, the people who left were called optanti ("choosing"), while they call themselves esuli ("exiles"). About 14,000 Italians chose to remain in the Yugoslav zone, currently divided between Slovenia and Croatia.

The Tangier International Zone was a 373 square kilometre protectorate controlled by several countries in the Moroccan city of Tangier and its environs between 1923 and 1956. Much like the Shanghai International Settlement, the government and administration of the zone was in the hands of a number of foreign powers.

The Green Line separating Southern Cyprus and Northern Cyprus is considered an International Zone because the United Nations operate and patrol within the buffer zone. The buffer zone was established in 1974 due to ethnic tensions between Greek and Turkish Cypriots. The green line is a demilitarised zone and thus acts in the same way as the 38th parallel separating the Republic of Korea

and North Korea. The United Nations currently has its headquarters for the UNFICYP at the abandoned Nicosia International Airport, where the majority of peacekeepers are based and where talks between the two governments are held.

Flags of United Nations member states flying outside the United Nations Headquarters complex in New York City.

Nanjing Road (then romanised as Nanking Road) in Shanghai, within the Shanghai International Settlement, a concession administered by multiple foreign powers during the late Qing Dynasty.

The four sectors of occupation in Vienna between 1945 and 1955.

United Nations Partition Plan for Palestine, showing the city of Jerusalem as an international zone

Map of the Free Territory of Trieste, showing its two administrative zones, one of which was later absorbed by each of its two neighbours (Slovenia and Croatia were both part of Yugoslavia at the time).

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