What historical laws targeted dual nationals and what were their outcomes?
Executive summary
A sequence of national laws and bilateral treaties from the late 19th through the mid-20th century deliberately targeted dual nationals by creating mechanisms for forced expatriation, renunciation, or loss of rights when citizens acquired or exercised foreign nationality, with practical outcomes ranging from disenfranchisement to diplomatic friction [1] [2] [3]. From roughly 1990 onward many states relaxed those rules and international instruments began to treat multiple nationality as a manageable consequence of migration rather than an intolerable danger, producing higher naturalization rates and new legal protections even as security and public‑office restrictions persist [2] [4] [5].
1. The 19th‑century turn: Expatriation declared and policed
The United States formally repudiated the doctrine of perpetual allegiance with the Expatriation Act of 1868, which articulated a right to renounce citizenship and set the stage for later rules that treated certain acts as evidence of abandoning U.S. nationality [1] [6]. That shift did not mean tolerance for overlapping loyalties: U.S. diplomatic practice and the so‑called Bancroft treaties used mechanisms of renunciation and “election” to prevent dual claims—reversing naturalization if a migrant returned for extended periods and policing conduct thought likely to create conflict between states [2] [1]. The practical effect was a legal regime that punished conduct seen as inviting dual allegiance rather than recognizing plural membership [1] [2].
2. Codifying loss: The Expatriation Act of 1907 and mid‑century rules
Early 20th‑century statutes expanded involuntary termination grounds: the Expatriation Act of 1907 and related regulations made marriage to a foreigner, prolonged residence abroad, service for a foreign government or armed forces, and other acts triggers for expatriation under U.S. law [3] [7]. Through mid‑century practice the United States at times applied what critics have called a “hair‑trigger” standard—loss of citizenship for acts like voting in another country—while courts and later jurisprudence complicated and narrowed those doctrines [8] [7]. High‑profile judicial rulings, administrative regulations, and occasional congressional restorations illustrated both the reach and the contestation of forced‑loss rules [3] [7].
3. International experiments: Treaties, conventions and the failure to harmonize
States also pursued bilateral and multilateral devices to manage multiple nationality, such as the Bancroft treaties and the 1930 Hague Convention, but the latter attracted few ratifications and failed to eliminate plural nationality or the disputes it prompted [2] [9]. European efforts culminated in later instruments—the 1963 and ultimately the 1997 European Convention on Nationality—that shifted language from seeing multiple nationality as an evil to seeking solutions that balance state interests and individual rights [9] [10]. The patchwork of treaties reproduced a central reality: legal tools existed to reduce dual nationality, but they rarely produced uniform outcomes across jurisdictions [9].
4. Concrete outcomes: disenfranchisement, military burdens, migration behavior
The core, measurable consequences of laws targeting dual nationals were loss of nationality or civil rights, obligations to perform military service, and lowered rates of naturalization where home‑state renunciation was required—factors that depressed formal citizenship uptake and produced practical burdens for migrants [8] [7] [4]. Countries that enforced automatic loss on acquiring another nationality, or required pre‑approval to retain nationality, effectively forced migrants to choose and in many cases discouraged naturalization abroad—which in turn shaped migration patterns and political ties [11] [4] [12]. Where enforcement was lax, dual nationality often persisted de facto despite formal prohibitions [4].
5. The late‑20th/21st‑century reversal and ongoing frictions
Since about 1990 dozens of states revised laws to permit or tolerate dual nationality, driven by globalization, diaspora politics, and changing human‑rights norms; this shift raised naturalization rates and normalized plural membership even as security concerns about classified access and public‑office eligibility remain debated [2] [4] [5]. International scholarship and instruments now frame plural nationality as a rights‑compatible status to be managed, not forbidden, but significant holdouts and legacy prohibitions—such as China’s longstanding ban—persist and are subject to scholarly calls for reform [5] [13]. Contemporary outcomes, therefore, are uneven: legal acceptance has increased, but practical restrictions and political anxieties have left a mixed landscape that reflects past laws’ imprint on present policy [2] [5].