their nationality laws,” but must comply with international human rights standards.9 In the United States, the term nationality refers to a person “owing permanent allegiance” to the country, whether a citizen or a non-citizen.10 Beyond US citizens, the term mostly applies to persons born in outlying US possessions, particularly America Samoa and Swains Island.11 For the purposes of this study, CMS applies the internationally recognized definition of a stateless person reflected in Article 1 of the 1954 Convention: “a person who is not considered as a national by any State under the operation of its law.” The term persons “at risk of statelessness” term denotes those with “difficulties furnishing relevant proof to establish their nationality” and who are therefore “at risk of not being considered nationals by a State” (UN 2011, 5).12 As noted in this report, due to serious insufficiencies in available data on either of these populations in the United States, the study is unable to identify with precision the number of people who meet these definitions, and it is not always possible to distinguish between the two populations. As such, the CMS report refers broadly to populations who are “potentially stateless or potentially at risk of statelessness.” CMS’s estimates of US residents who are potentially stateless or potentially at risk of statelessness include persons who may have gained nationality in their country of origin or in a third country. However, its estimates do not include US citizens. Some stateless persons may ultimately become US citizens, but as the United Nations High Commissioner for Refugees (UNHCR) Handbook on Protection of Stateless Persons provides, “statelessness determinations are not “predictive exercises” regarding who may or may not become a citizen, and stateless persons may be “partway through a process of acquiring nationality” (UNHCR 2014g, 20). UNHCR has commissioned several stateless mapping exercises for other nations.13 This study differs from those UNHCR studies due to a range of factors. With perhaps one exception (the United Kingdom), these other states lack the diversity of the US foreign-born population and of residents who are potentially stateless or potentially at risk of statelessness. Moreover, the overwhelming majority of these studies do not seek to estimate the nation’s stateless population. In addition, they rely on tools to identify the stateless—like local or central population registries— that are not available and not likely to be available in the United States.14 US administrative data on immigrants and refugees may be useful in identifying some categories 9 Id. 10 Immigration and Nationality Act (INA) §101(a)(22). 11 INA §308 sets forth the categories of US nationals who are not US citizens at birth, including persons born in an “outlying possession of the United States on or after the date of formal acquisition of such possession.” 12 The UN provides that “[n]ecessary forms of proof [to establish nationality] may either relate to the question of whether a person is a national (for instance a national identity document or passport), or to the legal requirements which a person needs to meet in order to be considered a national. Such requirements generally refer to links a person has with the State” (UN 2011, 5-6). Difficulties in establishing nationality can result from inadequate “birth registration, civil registration and other documentation systems” and ineffective “public administration in this regard” (ibid., 6). 13 UNHCR is the UN agency mandated by the UN General Assembly, through a series of resolutions, with the task of preventing and reducing statelessness and protecting stateless persons around the world. See e.g., U.N. General Assembly Resolution A/RES/50/152 at ¶ 14 (1995) (indicating that UNHCR’s statutory international protection function includes efforts on behalf of stateless persons); see also A/RES/61/137 ¶ 4 (urging continued UNHCR efforts “in regard to identifying stateless persons, preventing and reducing statelessness, and protecting stateless persons”). 14 They also rely on census and administrative data sources akin to US data sources. 3