2011] AN INTERNATIONAL LAW OF CITIZENSHIP 695 to states the terms of their membership rules.3 That is now changing. Bars on gender discrimination in citizenship practice, as well as constraints on the termination of citizenship, are hardening. Recent developments point to the emergence of norms that require the extension of territorial birthright citizenship in some cases and that limit discretion concerning naturalization thresholds. International law may also come to protect an individual’s right to maintain multiple nationality.4 These and other elements of a new regime relating to citizenship practice are emerging through multiple channels of decentralized international lawmaking. Some are found in international human rights instruments. In recent years the treaty committees associated with these regimes have moved aggressively in applying treaty terms to citizenship practice. Regional institutions, especially those of Europe and the Americas, have been receptive to a rights conception of citizenship practice. State practice also points toward the new frame,5 the result of both horizontal and vertical pressures, including as applied by nonstate actors. These trends reflect a reconceptualization of citizenship status, shifting from an identity to a rights frame. (The reconceptualization has reflected the shift away from the use of the term “nationality” to denote the formal tie between the individual and the state, and toward the now more appropriate use of “citizenship.”)6 It is still not possible, however, to speak generally of 3 See, e.g., RUTH DONNER, THE REGULATION OF NATIONALITY IN INTERNATIONAL LAW 17 (2d ed. 1994) (“[n]ationality may only be handled as a problem of the choice of law, when a tribunal has to decide what nationality law to apply”). 4 On top of the general interest in citizenship theory, dual citizenship has attracted particular attention. See, e.g., ALFRED M. BOLL, MULTIPLE NATIONALITY AND INTERNATIONAL LAW (2007); DUAL CITIZENSHIP IN EUROPE: FROM NATIONHOOD TO SOCIETAL INTEGRATION 171, 174 (Thomas Faist ed., 2007); DUAL CITIZENSHIP IN GLOBAL PERSPECTIVE: FROM UNITARY TO MULTIPLE CITIZENSHIP (Thomas Faist & Peter Kivisto eds., 2007); DUAL NATIONALITY, SOCIAL RIGHTS AND FEDERAL CITIZENSHIP IN THE U.S. AND EUROPE: THE REINVENTION OF CITIZENSHIP (Randall Hansen & Patrick Weil eds., 2002); RIGHTS AND DUTIES OF DUAL NATIONALS: EVOLUTION AND PROSPECTS (Kay Hailbronner & David A. Martin eds., 2003). The classic earlier treatment of the subject is Nissim Bar-Yaacov’s 1961 study, Dual Nationality 266 (1961). 5 In addition to theory-oriented work, major recent collective initiatives have undertaken empirical studies of state citizenship practice. The European Union has funded a continuing project to document citizenship practices in Europe. See ACQUISITION AND LOSS OF NATIONALITY: POLICIES AND TRENDS IN 15 EUROPEAN COUNTRIES (Rainer Bauböck, Eva Ersboll, Kees Groenendijk, & Harald Waldrauch eds., 2005); CITIZENSHIP POLICIES IN THE NEW EUROPE (Rainer Bauböck, Bernhard Perchinig, & Wiebke Sievers eds., 2007). The Carnegie Endowment for International Peace sponsored a three-volume initiative on the subject: CITIZENSHIP POLICIES FOR AN AGE OF MIGRATION (T. Alexander Aleinikoff & Douglas Klusmeyer eds., 2002); CITIZENSHIP TODAY: GLOBAL PERSPECTIVES AND PRACTICES (T. Alexander Aleinikoff & Douglas Klusmeyer eds., 2001); FROM MIGRANTS TO CITIZENS: MEMBERSHIP IN A CHANGING WORLD (T. Alexander Aleinikoff & Douglas Klusmeyer eds., 2000); see also IRENE BLOEMRAAD, BECOMING A CITIZEN: INCORPORATING IMMIGRANTS AND REFUGEES IN THE UNITED STATES AND CANADA (2006) (comparative study of naturalization); MARC MORJÉ HOWARD, THE POLITICS OF CITIZENSHIP IN EUROPE (2009) (undertaking quantitative empirical survey). Although much of this work has been focused on European and North American practice, important work has been undertaken on other regions. See, e.g., ERIN AERAN CHUNG, IMMIGRATION AND CITIZENSHIP IN JAPAN (2010); CITIZENSHIP AND THE STATE IN THE MIDDLE EAST (Nils A. Butenschon, Uri Davis, & Manuel Hassassian eds., 2000); BRONWEN MANBY, CITIZENSHIP LAWS IN AFRICA: A COMPARATIVE STUDY (2009); BRONWEN MANBY, STRUGGLES FOR CITIZENSHIP IN AFRICA 5 (2009). 6 In the modern era, “nationality” was used to designate the status by which an individual is tied to a state for international purposes, whereas “citizenship” denoted the status for purposes of municipal law. See, e.g., 3 JOHN BASSETT MOORE, A DIGEST OF INTERNATIONAL LAW 273 (1906); Maximilian Koessler, Subject, Citizen, National, and Permanent Allegiance, 56 YALE L.J. 58, 62– 63 (1946 – 47). The distinction was necessary in a world in which status was variable under domestic law, especially as between republican and nonrepublican systems, the latter denominating individuals as subjects (or slaves) rather than as citizens. Today, the distinction is vanishingly small. Many commentators use the terms interchangeably. See, e.g., RUBIO-MARÌN, supra note 2, at 19 n.7; Kim Barry, Home and Away: The Construction of Citizenship in an Emigration Context, 81 NYU L. REV. 11, 14 n.6 (2006); Karen Knop, Citizenship, Public and Private, 71 LAW & CONTEMP. PROB. 309, 309 n.1 (2008); see also This content downloaded from 82.196.111.31 on Thu, 07 Oct 2021 15:20:30 UTC All use subject to https://about.jstor.org/terms