S864 COLUMBIA JOURNAL OF TRANSNATIONAL LAW [56:S855 Concurrent with the wartime rise in stateless and undocumented displaced persons, States across Europe began implementing new or stricter passport regimes. 47 Controlling the movement of nonnationals was viewed as a means of “assuring [States’] protection of the military and economic interests.” 48 This left hundreds of thousands of stateless persons stranded in Eastern Europe, unable to travel to States where they could find work and be free of persecution. 49 C. Changes in Practice and New Regulations in International Law Though the extension of nationality was once viewed as a matter purely of municipal law, the PCIJ pronounced in 1923 that “[t]he question whether [nationality] is or is not solely within the domestic jurisdiction of a State . . . depends on the development of international relations.” 50 The PCIJ further determined that State authority to decide who would be regarded as a national was “subject to . . . Treaty obligations.” 51 That same year, the ILA stated as fact that “the question of what nation a man may make himself a subject of” is a matter of public international law. 52 Its Committee on Nationality specified that international law should provide mechanisms for avoiding statelessness, an “evil[]” associated with nationality practice 53 that could subject a man to improper conscription, detention, or displacement. 54 Statelessness was addressed not only in the rhetoric of the ILA but also in the practice of States. Responding to the mass displacement of persons across Europe, States created a stopgap method for addressing stateless persons’ lack of documentation and restrictions on movement. In 1922, the League of Nations, through a series of treaties, 55 began issuing “Nansen Passports” to recognize Doc. A.21 1937 XII (1937). 47. John H. Simpson, The Refugee Problem, 17 INT’L AFF. (ROYAL INST. INT’L AFF.) 607, 607 (1938). 48. Egidio Reale, The Passport Question, 9 FOREIGN AFF. 506, 506 (1931). 49. Id. at 507–08. 50. Nationality Decrees Issued in Tunis and Morocco, supra note 19, ¶ 24. 51. Acquisition of Polish Nationality, Advisory Opinion, 1923 P.C.I.J. (ser. C) No. 3, at 16 (Aug. 27). 52. Conference on Nationality and Naturalization, 32 INT’L L. ASS’N R. CONF. 1, 5 (1923). 53. Id. at 7. 54. Report of the Committee on Nationality and Naturalization, 33 INT’L L. ASS’N R. CONF. 22, 23 (1924). 55. See Arrangement with Respect to the Issue of Certificates of Identity to Russian Electronic copy available at: https://ssrn.com/abstract=2954729