Migrant Protection Categories in International Law & Practice 

By John Cerone

“Do not come.” With these words, U.S. Vice-President Kamala Harris, during a June 2021 press briefing in Guatemala, attempted to discourage would be migrants from attempting to enter the U.S. without the normally requisite approvals and documentation. In her speech, she reiterated the existence of legal pathways for migration, and emphasized that one of the priorities of the current US administration would be to “discourage illegal migration.” 

Since that time, irregular migrant encounters at the southern border have reached numbers not seen in over 20 years. Indeed, the past two years have witnessed over four million encounters between Customs and Border Protection (CBP) officials and undocumented migrants. Major US cities have declared states of emergency, with New York City Mayor Erik Adams citing the increasing “influx of asylum seekers arriving to New York City from the Southern border.” A similar emergency declaration was recently made by Massachusetts Governor Maura Healey. In the Spring of 2023, the Pentagon announced the deployment to the southern border of 1500 troops to join 2,500 National Guard members already in place to support the work of border agents. 

At the same time, the Biden administration has engaged in mass expulsions of migrants, with the expulsion of thousands of Haitian migrants and the expansive use of COVID restrictions attracting particular media attention. Human rights groups have decried the administration’s policies as inhumane and illegal, pointing out that many of those expelled are ‘asylum seekers’. Other organizations refer to the situation at the southern border as one of “mixed migration”. Still others pointed to the increased arrival of “unaccompanied children” as a result of expelled families choosing to separate in order to increase the odds of a child’s admission. 

Of course such phenomena, and the related controversies, are not limited to this part of the world. Among dozens of migration hot spots around the globe, international news outlets have featured stories on “trafficking migrants” to the border between Belarus and Poland,i the ongoing displacement crisis in South Sudan ii and renewed “refugee” flows from Sudan,iii the UK policy of sending to Rwanda certain migrants who arrive “illegally,”iv the 7.6 million Ukrainian “refugees” displaced by the ongoing Russia-Ukraine war,v and resort to “people smugglers” by Afghans seeking to flee their country.vi    

What role does international law play in regulating migration? Is there such a thing as “illegal” migration? What does it mean for migration to be “irregular”, or for it to be “mixed”?  Is there a difference between a migrant, an asylum-seeker, a refugee, and an asylee? Is there a difference between “trafficking” and “smuggling” of people? Are any of these legally defined terms, or are they merely descriptive?   

The purpose of this briefing is to provide a first step in understanding the legal situation by clarifying some of the relevant terms and providing a brief overview of various categories into which migrants might fall under international law.vii 


There is no universally accepted definition of the term ‘migrant’ in international law; nor is there a consistent practice in usage of the term. It can be understood in a very narrow sense, as individuals who are voluntarily relocating internationally for an indefinite duration, or it could be understood in a very broad sense, including anyone, in the words of the BBC, “on the move.”viii 

Organizations who work on migration issues have adopted their own definitions for purposes of their work. According to the International Organization for Migration, the term “migrant” is: 

“An umbrella term, not defined under international law, reflecting the common lay understanding of a person who moves away from his or her place of usual residence, whether within a country or across an international border, temporarily or permanently, and for a variety of reasons.”ix 

Like the BBC definition, this broad definition applies to everyone on the move, irrespective of motivation, voluntariness, or legal status.  

The term “economic migrant” is sometimes used to describe migrants who have an economic motive. However, it is not a legal term. The fact that a migrant has an economic motive does not disqualify them from international legal protections if their circumstances otherwise render those protections applicable.x  

While there is no specific legal protection for migrants as a group in international law, they are of course entitled to the protection of international human rights law, and they may also be entitled to additional rights depending on whether they fall into a protected category. 

Irregular migrants, or migrants in an irregular situation 

The term “irregular migrant” also lacks a definition in international law. Nonetheless, there is consensus on its meaning, as reflected in international practice.   

All countries have established procedures regulating the entry and stay of foreigners. Where foreign migrants enter or remain in such countries without complying with those procedures, they are said to have entered irregularly or are said to be in an irregular situation.xi   

International law does not prohibit irregular entry. Whether irregular entry constitutes an illegal act is dependent upon the domestic law of the concerned country. In those countries where such entry or stay constitutes a crime under domestic law, such migrants might be referred to as “illegal” migrants. However, even in those countries where it is a crime, it would be more accurate to refer to these individuals as migrants who have illegally entered or who have committed illegal entry, rather than using the adjective ‘illegal’ to modify the noun ‘migrant.’  

In the absence of a prohibition on migration in international law, and because the determination of legal entry or presence is based on domestic law, which varies from state to state, the general term in international practice is “irregular migration.” 

 Migrant Workers 

There are several different definitions of the term “migrant worker” in international law, and these definitions vary among treaty regimes. The most significant of these treaties are Conventions 97 (1949) and 143 (1975) of the International Labour Organization, and the International Convention on the Protection of the Rights of All Migrant Workers and Members of Their Families.  

The term “migrant worker” does not appear in ILO Convention 97. The Convention instead uses the term “migrant for employment,” which it defines as: 

“a person who migrates from one country to another with a view to being employed otherwise than on his own account and includes any person regularly admitted as a migrant for employment.”xii 

ILO Convention 143 uses the term “migrant workers,” employing a similar definition. Migrants in an irregular situation are largely excluded from protection under both treaties.  

The International Convention on the Protection of the Rights of All Migrant Workers and Members of Their Families (the “Migrant Workers Convention” or “MWC”) is explicitly a human rights treaty, and as such, utilizes a broad definition of migrant workers, including those in an irregular situation.xiii According to article 2(1) of the MWC, “The term ‘migrant worker’ refers to a person who is to be engaged, is engaged or has been engaged in a remunerated activity in a State of which he or she is not a national.”xiv Certain categories of migrants are excluded from the protection of this treaty, most notably, refugees and stateless persons.xv 

Asylum-seekers, asylum, and asylees 

At first glance, the meaning of the term asylum-seeker seems straight forward enough. An asylum-seeker is simply a migrant who is seeking asylum, irrespective of whether they may have any particular status under international law. It turns completely on the will of the individual, without regard to their factual circumstances. Similarly, the term asylee is typically used to refer to one who has been granted asylum.  

Discerning the meaning of the term ‘asylum,’ on the other hand, is a more complex undertaking. As with many of the terms surveyed, there is no single definition of asylum in international law. Indeed, there are various types and understandings of asylum under international and national law. xvi At the most general level, the grant of asylum by a state entails allowing an individual to enter or remain within the state’s territory or jurisdiction (e.g., in diplomatic premises) rather than being sent to or left in a place where the individual faces harm.  

As such, there is little legal content to the concepts of asylum, asylum seeker, and asylee in international law. The rights encompassed are largely defined by domestic law.  

However, the term asylum can have a narrower, more specific meaning, depending upon the context or particular legal framework. For example, in some national systems, the term asylum refers only to the granting of a durable right to reside to certain categories of individuals, and this grant may also encompass a broad range of rights beyond the mere right to remain in the territory. The paradigm group of such individuals would be refugees. For example, the legal test for eligibility for what the US calls asylum is virtually identical to the requirements for refugee status in international law.xvii  


There are many different legal definitions of “refugee,” depending upon the particular framework under consideration. There is variation within and among international, regional, and national legal systems.  

Within international law, the most widely applicable definition of the term “refugee” is found in the 1951 Convention relating to the Status of Refugees, as modified by the 1967 Protocol relating to the Status of Refugees (“Refugee Convention and Protocol”). Under this treaty regime, a refugee is defined as any person who: 

“owing to well-founded fear of being persecuted for reasons of race, religion, nationality, membership of a particular social group or political opinion, is outside the country of his nationality and is unable or, owing to such fear, is unwilling to avail himself of the protection of that country; or who, not having a nationality and being outside the country of his former habitual residence, is unable or, owing to such fear, is unwilling to return to it.” xviii 

Notably, this definition requires that the individual fear a particular kind of harm – persecution on the basis of race, religion, nationality, membership of a particular social group or political opinion. The definition makes no mention of situations of armed conflict, rampant lawless violence, natural disasters, failed states, or other catastrophic situations. It is primarily with respect to this element that regional and domestic legal definitions of refugee vary, typically by broadening the types of feared harm that will qualify an individual for refugee status. xix  

The definition of refugee also varies under national law. States are free to define the term refugee as they see fit, subject to their international obligations. As international law sets forth minimum standards, each state that is bound by international refugee law is free to adopt a broader definition than that set forth in the rules of international law applicable to that state. xx  

Practice within a given system may also put a gloss on legal terminology, adding an additional layer of potential confusion. For example, within the US legal system the term ‘refugee’ is usually used to refer specifically to individuals abroad who have been determined to be refugees, typically by a third party such as UNHCR. Thus, when the US government speaks of “refugees” it almost always in the context of the formal process of resettling refugees from abroad, as opposed to refugees who have simply entered the US and who may apply for asylum. This latter group of individuals is typically referred to as “asylum-seekers” or, if granted asylum, “asylees.” Hence, when the US speaks of a “refugee cap,”xxi it is referring only to the number of refugees being resettled from abroad through official channels, and does not include refugees who have entered or otherwise find themselves in the US. There is no “cap” on this latter group of refugees.    

International refugee law confers a broad range of legal protections on refugees. These obligations primarily apply to the state in which the refugees are located. The level of protection varies according to such factors as whether their presence is lawfulxxii and the duration of their presence in the territory. However, neither the Refugee Convention nor its 1967 Protocol explicitly require the granting of asylum to refugees. Thus, the determination of whether an individual is a refugee in international law is distinct from the issue of whether an individual will be granted asylum, which the Refugee Convention leaves to the discretion of states and is thus governed by domestic law. 

Nonetheless, one of the most important protections for refugees is the requirement of non refoulement. xxiiiIn the words of the Refugee Convention, “No Contracting State shall expel or return (‘refouler’) a refugee in any manner whatsoever to the frontiers of territories where his life or freedom would be threatened on account of his race, religion, nationality, membership of a particular social group or political opinion.”xxiv Thus, while states are not obliged to grant refugees asylum, they are obliged to refrain from deporting refugees to particular places; i.e. those places where they would face the type of persecution that leads to refugee status. 

The protection of non-refoulement applies to all refugees. However, refugees are not the only group to whom it applies.

Victims (actual or potential) of Torture and Enforced Disappearance  

International law also expressly imposes an obligation of non-refoulement in relation to actual or potential victims of torture or enforced disappearance.xxv In particular, this protection exists for individuals in relation to whom “there are substantial grounds for believing that he would be in danger of being subjected to torture,”xxvi and when “there are substantial grounds for believing that he or she would be in danger of being subjected to enforced disappearance.”xxvii  

In order for states parties to the respective treaties to comply with these obligations, they must analyze the circumstances of migrants to determine whether they are potential victims of torture or enforced disappearance in light of the legal definitions of these crimes.xxviii Notably, both crimes require some degree of state involvement, with acquiescence as the necessary minimum.  

While these crimes may overlap with the persecution feared by refugees, they are distinct in several respects. They are narrower by limiting the category to a more specifically defined type of harm. Yet they are also broader by not requiring that the harm be inflicted on discriminatory grounds. Thus, it is possible to be a potential victim of one of these crimes and not be a refugee, and vice-versa. 

Smuggled Migrant  

International law provides very few protections for smuggled migrants, beyond the minimum standards of human rights law applicable to all. Migrant smuggling is subject to a suppression regime set forth in the Protocol against the Smuggling of Migrants by Land, Sea and Air, which is one of three protocols supplementing the United Nations Convention against Transnational Organized Crime. In addition to requiring the adoption of suppression measures under domestic law, the Protocol also imposes certain minimal obligations of protection and assistance for migrants who have been smuggled, with a particular focus on positive obligations to protect them from violence that may result from having been smuggled.xxix 

Article 3(a) of the Protocol defines “Smuggling of migrants” as “the procurement, in order to obtain, directly or indirectly, a financial or other material benefit, of the illegal entry of a person into a State Party of which the person is not a national or a permanent resident.” The language “in order to obtain, directly or indirectly, a financial or other material benefit,” is particularly noteworthy. The goal of obtaining a benefit is key to distinguishing migrant smuggling from humanitarian assistance measures that might also lead to illegal entry.  

A separate protocol to the same convention creates a suppression regime for human trafficking.  

Victim of Human Trafficking 

Victims of human trafficking are entitled to specific protections under articles 6 to 8 of the Protocol to Prevent, Suppress and Punish Trafficking in Persons, Especially Women and Children, which also supplements the United Nations Convention against Transnational Organized Crime. As one might expect, the protections for victims of human trafficking are more expansive than those afforded to smuggled migrants, including an obligation to “consider adopting legislative or other appropriate measures that permit victims of trafficking in persons to remain in its territory, temporarily or permanently, in appropriate cases.”xxx  

While the two protocols were drafted according to a conception that migrant smuggling and human trafficking are distinct phenomena, there is a considerable overlap in practice. A key distinction between human trafficking and migrant smuggling is the requirement that deceptive or abusive means be employed against the victim, and that the traffickers must have an exploitive purpose.xxxi However, given the coercive circumstances in which smuggled migrants tend to find themselves, and the willingness of smugglers to exploit the resulting vulnerability, the line between trafficking and smuggling tends to blur. 

Despite this blurring, the determination of whether an individual falls under one, the other, or both of the Protocols has significant legal consequences, both in terms of available legal protections, as well as, of course, criminal consequences for perpetrators.  


An individual may be any or all of the following: a migrant, an irregular migrant, a smuggled migrant, a victim of human trafficking, a potential victim of torture or enforced disappearance, a refugee, a migrant worker, and an asylum seeker. All of the foregoing are entitled to some degree of legal protection under international law. All are afforded the baseline protection of international human rights law. Some are granted additional rights based on their particular status or situation, necessitating individualized assessments of each individual seeking protection. 

In light of the spectrum of overlapping categories surveyed above, it is prudent to avoid coarse characterizations of migrant groups. The various categories encompass a vast array of circumstances, necessitating individualized assessments for each migrant to determine whether and to what extent they are entitled to the protection of international, regional, and/or national law.    


[1] “Belarus migrants: What routes do they use to reach Minsk?” BBC News, Nov. 11, 2021.

[1] UN, Aid Agencies Appeal for $1.2 Billion for South Sudan Refugees, VOA News, March 19, 2022 (https://www.voanews.com/a/un-aid-agencies-south-sudan-refugees-appeal/6492442.html)

[1] “Sudan crisis sparks fresh wave of Darfur refugees into Chad,” BBC News, May 3, 2023.

[1] Oral statement of the Home Secretary to the House of Commons on the government’s Migration and Economic Development Partnership with Rwanda, June 15, 2022. (https://www.gov.uk/government/speeches/oral-statement-on-rwanda)

[1] After fleeing war, Ukrainians struggle to settle around Europe, Reuters news, October 10, 2022 (https://www.reuters.com/world/europe/after-fleeing-war-ukrainians-struggle-settle-around-europe-2022-10-10/).

[1] “Desperate Afghans turn to people smugglers for help fleeing the country,” BBC News, Nov. 8, 2021.

[1] This overview draws upon J. Cerone, “Migrant Categorization under the Patchwork of International, Regional, and National Law,” in K. Jacobsen and N. Majidi (eds.), Handbook on Forced Migration, Edward Elgar Publishing (forthcoming 2023).

[1] See, e.g., “Lampedusa: More than 1,000 Migrants Arrive on Italian Island,” BBC News, May 9, 2021, https://www.bbc.com/news/world-europe-57049130., at “Note on Terminology.”

[1]  “Glossary on Migration,” No 34 (Geneva: International Organization for Migration, 2019), 132, https://publications.iom.int/system/files/pdf/iml_34_glossary.pdf. IOM includes several caveats indicating that it is neither speaking ex cathedra, nor purporting to participate in the creation of a legal categories. Regarding this definition of migrant, the Glossary notes, “The present definition was developed by IOM for its own purposes and it is not meant to imply or create any new legal category.” 

[1] If an individual’s unwillingness to return to their country of origin is attributable exclusively to economic concerns, then they will be ineligible for certain humanitarian protections. However, this is not because of their economic motivations, but because of the absence of the requisite mental state, where such mental state is a required element for the legal protection to be applicable, as, for example, with refugee status.  

[1] This usage is consistent with Migrant Workers Convention which stipulates that migrant workers are to be considered as “documented or in a regular situation” if they are “authorized to enter, to stay and to engage in a remunerated activity in the State of employment pursuant to the law of that State and to international agreements to which that State is a party.” Conversely, those migrant workers who do not comply with these conditions are considered as “non-documented or in an irregular situation.”

[1] Convention (No. 97) concerning migration for employment (revised 1949), art. 11(1), January 7, 1949, 120 U.N.T.S. 71.. Article 11(2) excludes from the scope of the Convention “(a) frontier workers; (b) short-term entry of members of the liberal professions and artistes; and (c) seamen.”

[1] Nonetheless, the Convention affords greater rights to those migrant workers who are in a regular situation.

[1] Notwithstanding the breadth of this definition, certain categories of migrants are excluded by article 3 of the MWC. Notably among the excluded groups are “[r]efugees and stateless persons, unless such application is provided for in the relevant national legislation of, or international instruments in force for, the State Party concerned.” See MWC, article 3(d).. Note, however, that the Committee on Migrant Workers, the monitoring body established by the MWC, has adopted a narrow interpretation of this exclusion. It interprets the term “refugees” as including only those refugees who have been determined to be such under national law and where the state has afforded them all of the legal protections for refugees that are required under international law.

[1] Art. 3(d), MWC.

[1] A number of terms are used to refer to asylum, some of which may be used to refer to different modalities of granting asylum, but, again, usage is inconsistent. The term ‘political asylum’ is often used interchangeably with the term ‘asylum,’ but it can also be used to refer to the narrower context of refusing an extradition request on grounds that a criminal offense was of a political nature. The term ‘diplomatic asylum’ is sometimes used to refer to a grant of asylum on diplomatic premises, as opposed to on a state’s own territory, which is sometimes referred to as “territorial asylum.”’ A state’s fulfillment of an obligation of non-refoulement is also occasionally referred to as a type of asylum.

[1] However, as the grant of asylum is discretionary in international law, qualifying for refugee status, while necessary, does not guarantee a grant of asylum in the US.

[1] Convention relating to the Status of Refugees, art. 1 A (2), July 28, 1951, 189 U.N.T.S. 137 [hereinafter Refugee Convention], as modified by Protocol relating to the Status of Refugees, art. I(2), January 31, 1967, 606 U.N.T.S. 267. Note that the 1951 Convention contained a temporal limitation, and also permitted geographical limitations, that essentially limited its application to the particular group of World War II refugees. This restricted definition remains applicable to those states that are parties to the 1951 Convention, but are not parties to the 1967 Protocol. In addition, the geographical limitation may be retained even by states that are parties to both the Convention and Protocol. For example, Turkey, upon acceding to the Protocol, opted to retain the geographical limitation restricting its application to persons who have become refugees as a result of events occurring in Europe. 

[1] Examples of such regional definitions are found in the Organization of African Unity’s (now African Union) Convention Governing the Specific Aspects of Refugee Problems in Africa (OAU Convention governing the specific aspects of refugee problems in Africa, October 9, 1969, 1001 U.N.T.S. 45, art. 1(2)), and in the Cartagena Declaration on Refugees (Cartagena Declaration on Refugees, Colloquium on the International Protection of Refugees in Central America, Mexico and Panama, November 22, 1984), both of which include a much broader spectrum of harms. Although the Cartagena declaration is not a treaty, and thus not a legally binding instrument, this definition has been adopted in the domestic law of a number of Latin American states.

[1] For example, the definition of refugee under US law includes, under certain circumstances, persons who have not crossed a border or are otherwise still within their country of nationality or habitual residence. See, Immigration and Nationality, 8 U.S.C. §§ 1101(a)(42) (1986). Of course, if a state adopts a narrower definition than that required by applicable international law, then that state would likely wind up in breach of its international obligations.

[1] “Joe Biden raises Trump refugee cap after backlash,” BBC News, May 4, 2021, https://www.bbc.com/news/world-us-canada-56975402; Sean Sullivan, “Biden says he will raise refugee cap from 15,000 to 62,500, after widespread criticism for extending Trump-era levels,” Washington Post, May 3, 2021, https://www.washingtonpost.com/politics/biden-refugee/2021/05/03/1b833126-ac4d-11eb-ab4c-986555a1c511_story.html.

[1] Lawful presence is determined by domestic law. Note that art. 31 of the Refugee Convention provides for non-penalization of irregular entry in certain circumstances. It is unclear, however, whether the obligation of non-penalization converts an otherwise unlawful presence into lawful presence.

[1] This protection is particularly important in the absence of a grant of asylum. While refugees have the right to request asylum, they do not have the right to have asylum granted. The obligation of non-refoulement helps to ensure that they will not be expelled to a place where they would face persecution.

[1] Refugee Convention, art. 33(1).

[1] In addition, most international and regional human rights bodies have found that the obligation of non-refoulement applies to all those who would face particularly serious human rights violations in the country to which they would be sent, notwithstanding the fact that the respective human rights treaty makes no express reference to such an obligation. According to these bodies, this includes certain serious violations of the International Covenant on Civil and Political Rights, the Convention on the Elimination of All Forms of Discrimination Against Women, and the European Convention on Human Rights, among others. This much broader swath of protections further demonstrates the false conception of refugees as the exclusive subjects of international legal protection of a humanitarian nature.       

[1] Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment, art. 3(1), Dec. 10, 1984, 1465 U.N.T.S. 85.

[1]  International Convention for the Protection of All Persons from Enforced Disappearance, art. 16(1), Dec. 20, 2006, 2716 U.N.T.S. 3.

[1] Article 1 of the Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment defines torture as: “any act by which severe pain or suffering, whether physical or mental, is intentionally inflicted on a person for such purposes as obtaining from him or a third person information or a confession, punishing him for an act he or a third person has committed or is suspected of having committed, or intimidating or coercing him or a third person, or for any reason based on discrimination of any kind, when such pain or suffering is inflicted by or at the instigation of or with the consent or acquiescence of a public official or other person acting in an official capacity.” The International Convention for the Protection of All Persons from Enforced Disappearance defines enforced disappearance as “the arrest, detention, abduction or any other form of deprivation of liberty by agents of the State or by persons or groups of persons acting with the authorization, support or acquiescence of the State, followed by a refusal to acknowledge the deprivation of liberty or by concealment of the fate or whereabouts of the disappeared person, which place such a person outside the protection of the law.”

[1]  Protocol against the Smuggling of Migrants by Land, Sea and Air, supplementing the United Nations Convention against Transnational Organized Crime, art. 16, November 15, 2000, 2241 U.N.T.S. 480. See also art. 5.

[1]  Protocol to Prevent, Suppress and Punish Trafficking in Persons, Especially Women and Children, supplementing the United Nations Convention against Transnational Organized Crime, art. 7(1), November 15, 2000, 2237 U.N.T.S. 319.

[1] Note that in the case of children, article 3(c) removes the requirement that deceptive or abusive means be employed. It provides, “The recruitment, transportation, transfer, harbouring or receipt of a child for the purpose of exploitation shall be considered ‘trafficking in persons’ even if this does not involve any of the means set forth in subparagraph (a) of this article. . . .”

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