The United States has never passed a law that formally allows dual citizenship. Instead, the answer to when the U.S. began allowing dual citizenship is a sequence of three dates: the Supreme Court’s 1967 ruling in Afroyim v. Rusk, which made it unconstitutional to strip citizenship without consent; the Court’s 1980 decision in Vance v. Terrazas, which required proof of intent to give up citizenship; and a 1990 State Department policy that presumed most Americans performing potentially expatriating acts meant to keep their citizenship. Together those three shifts turned dual nationality from something the government actively tried to prevent into something it quietly accepts.
The Rule Before 1967
For most of American history, citizenship was treated as exclusive. The prevailing legal theory held that a person could owe allegiance to only one sovereign at a time. In 1868, Congress passed the Expatriation Act, which declared “the right of expatriation is a natural and inherent right of all people.”1Congress.gov. Development of Expatriation Doctrine The law was written to protect naturalized Americans from being reclaimed by their birth countries, but it carried the same underlying assumption: choosing one nationality meant leaving the other behind.
Around the same time, the United States signed the Bancroft Treaties with several European nations, which required immigrants who naturalized here to give up their original citizenship. Congress later codified specific acts that would cause automatic loss of citizenship, first in the Nationality Act of 1940 and then in the Immigration and Nationality Act of 1952. Voting in a foreign election was on that list. So was serving in a foreign military.
In 1958, the Supreme Court endorsed this framework in Perez v. Brownell, upholding Congress’s authority to strip citizenship from an American who had voted in a Mexican election. That was the state of the law until 1967.
1967: Afroyim v. Rusk
The turning point came on May 29, 1967. Beys Afroyim, a naturalized citizen who had emigrated from Poland, moved to Israel and voted in an Israeli legislative election. When he tried to renew his U.S. passport, the State Department refused, citing Section 401(e) of the Nationality Act of 1940, which said a citizen would lose nationality by voting in a foreign political election.2Justia. Afroyim v Rusk, 387 US 253 (1967)
Afroyim argued the government had no constitutional authority to take his citizenship without his consent. In a 5–4 decision, the Supreme Court agreed. The majority held that the Citizenship Clause of the Fourteenth Amendment gives citizenship a constitutional status that Congress cannot override. The Court overruled Perez v. Brownell and concluded that a citizen has “a constitutional right to remain a citizen in a free country unless he voluntarily relinquishes that citizenship.”2Justia. Afroyim v Rusk, 387 US 253 (1967)
The practical effect was immediate. If the government could no longer automatically revoke citizenship for actions like foreign voting, then Americans could participate in the civic and legal life of other countries without forfeiting their U.S. status. This is the date most often cited as the beginning of dual citizenship in the United States, though the protection it created was still incomplete.
1980: The Intent Requirement in Vance v. Terrazas
The second major shift came in 1980. Laurence Terrazas held both American and Mexican citizenship from birth. To obtain a certificate of Mexican nationality, he signed a document that included a renunciation of his allegiance to the United States. The federal government moved to revoke his citizenship, arguing the act of renunciation was enough on its own.
The Supreme Court disagreed in part. In Vance v. Terrazas, the justices held that the government must prove, by a preponderance of the evidence, that the individual specifically intended to give up American citizenship, not just that they voluntarily performed an act that could be considered expatriating.3Legal Information Institute. Vance v Terrazas
That intent requirement turned out to be a strong practical shield. Administrative formalities performed abroad, like swearing an oath to obtain a passport or signing a declaration to get a national ID card, no longer automatically stripped a person of citizenship. The burden was now on federal authorities to demonstrate a conscious desire to abandon American nationality.
1990: The State Department’s Presumption
The constitutional protections were in place after 1980, but day-to-day decisions about citizenship loss still ran through the State Department. In 1990, the Department adopted an administrative policy that flipped the practical default. Under the new standard, the government would presume that a citizen who performed certain potentially expatriating acts, including naturalizing in a foreign country, declaring allegiance to a foreign state, or accepting a non-policy-level government position abroad, intended to keep their American citizenship.
Before that policy, an American who naturalized in another country might have to answer questions about whether they had given up their U.S. status. After 1990, the State Department assumed they had not, unless clear evidence showed otherwise. Combined with Afroyim and Vance, this administrative change is what pushed dual citizenship from a constitutional gray area into an ordinary, unremarkable status.
How the Federal Government Treats Dual Citizenship Now
No federal statute formally endorses or prohibits dual nationality. The State Department describes dual nationality as meaning “you are a national of 2 countries” and acknowledges that “a dual national generally has legal rights and obligations in both countries.”4U.S. Department of State. Dual Nationality Nobody is required to choose one nationality over another at any age, and there is no process by which the government forces a dual citizen to surrender a foreign passport.
There is one meaningful limit. The United States may not be able to provide full consular assistance to a dual citizen who is inside the country of their other nationality. That country may treat the person as its own citizen exclusively, which can restrict U.S. embassy staff from intervening in legal disputes, detention, or exit bans.4U.S. Department of State. Dual Nationality
Acts That Can Still Cost You Your Citizenship
Involuntary expatriation is essentially gone, but federal law still lists specific acts that can result in loss of nationality, provided they are performed voluntarily and with the specific intent to give up citizenship. Those acts include naturalizing in a foreign country after age 18, swearing allegiance to a foreign state after age 18, serving in a foreign military that is fighting against the United States or serving as an officer in any foreign military, working for a foreign government after age 18 if you hold that country’s nationality or the position requires an oath of allegiance, formally renouncing citizenship before a U.S. diplomatic or consular officer abroad, and committing treason or attempting to overthrow the government if convicted.5Office of the Law Revision Counsel. 8 USC 1481 – Loss of Nationality by Native-Born or Naturalized Citizen
The controlling word in that list is intent. Under the 1990 presumption, the State Department assumes that most of these acts, particularly naturalizing abroad or taking a routine oath, are not done with the intent to give up U.S. citizenship. The government has to overcome that presumption with evidence before it can revoke anyone’s nationality. That is the practical status of dual citizenship in the United States today, and the reason it works the way it does traces back to those three dates: 1967, 1980, and 1990.