Dual nationality
By William Wetherall
29 December 2025
On 1 December 2025, Senator Bernie Moreno, a Republication representing Ohio, introduced the Exclusive Citizenship Act of 2025, to establish that citizens of the United States must have "sole and exclusive allegiance to the United States." The bill provides that naturalizing aliens who would continue to possess the nationality of another country, after taking a sole-and-exclusive oath of allegiance to become a U.S. citizen, would have one year within which to renounce their foreign nationality (or nationalities) or lose their U.S. citizenship.
The main points in the proposed law are these.
1. An individual may not be a citizen or national of the United States while simultaneously possessing any "foreign citizenship" -- defined for the purpose of this act as "any status recognized by the government of a foreign country that confers on an individual the nationality or citizenship of such country or requires the allegiance of an individual to such country."
2. U.S. citizens who, after the date of the enactment of the law, voluntarily acquire a foreign citizenship shall be deemed to have relinquished U.S. citizenship.
3. Within one year of the date of the enactment of the law, U.S. citizens who, at the time of the enactment, also possess a foreign citizenship, shall submit written renunciation of the foreign citizenship to the Secretary of Homeland, or be deemed to have voluntarily relinquished U.S. citizenship.
These provisions resemble those in Japan's Nationality Law, and in the nationality laws of many other countries, in that voluntary acquisition of a foreign nationality is commonly a cause for loss of the country's nationality. In fact, this was the case in the United States, until 1990, when as a result of a series of earlier rulings in U.S. courts, the State Department changed its policy regarding its presumption of intent regarding retention of U.S. citizenship when naturalizing in another country.
Nationality, not citizenship
Moreno's definition of "citizenship" for the purposes of his bill is essential. While "citizenship" is the term commonly used in U.S. nationality laws, "nationality" is the term recognized in international private law, and on passports.
As a passport status signifying political affiliation with a recognized state or state-like entity, the term is "nationality", not "citizenship". In point of fact, U.S. passports declare only that the bearer possesses the "nationality" of the United States. Whether the bearer of a U.S. passport is a "citizen" or just a "national" of the United States is a purely domestic concern.
Nationality is something you either have or don't have. If you possess Japan's nationality, you are Japanese. If you don't, you're not. You cannot be half or any other fraction of Japanese.
You may have two or more nationalities, in which case you are a dual national or multinational. Or you may have none, in which case you are stateless -- an alien in the eyes of every country.
Unlike nationality, citizenship is not a 0 or 1 binary. Citizenship comes in different sizes and colors, depending on personal attributes like nationality, residential status, age, legal capacity, and possibly sex.
Tolerance of dual nationality
Tolerance of dual nationality was inconceivable in most states of the world until the middle of the 20th century. By then, degenderization -- the elimination of sexual distinctions -- in nationality standards had generally undermined the older principle of single nationality for internationally married couples and their offspring. Today, nationality -- while defined and regulated differently among sovereign states -- is almost universally regarded as a personal rather than collective family status.
During the last half of the 20th century, more states began to realize that they were unable to prevent dual nationality without trampling on personal rights. Between a rock and a hard place, states began to see that their fears of dual nationality stemmed more from nationalist paranoia than legal realities.
More commentators have concluded that dual nationality is not only harmless to a state's political integrity, but is generally beneficial for mixed-national families, which in turn are generally beneficial to the state. True, dual nationals are likely to encounter some conflicts between the laws of their countries of nationality in the course of their lives. But most such conflicts -- involving international private law -- are generally addressable by laws of laws and treaties that determine matters like applicable law, jurisdiction, and venue in cases of conflict.
Expatriating acts
Naturalization in another country is a potentially expatriating act in practically all countries. Until 1990, the State Department presumed that a U.S. citizen who naturalized in another country intended to forfeit his or her U.S. status. In 1967, the Supreme Court ruled that a Poland-born naturalized U.S. citizen, had a constitutional right to remain a U.S. citizen even though he voted in an Israeli election after becoming a U.S. citizen (Afroyim v. Rusk).
The 1967 ruling had a domino effect on a number of U.S. laws, treaties, and policies that had restricted dual nationality. The final dominoes fell after 1980, when the Supreme Court ruled that the United States could not expatriate a dual U.S.-Mexico national, born in the United States to Mexican parents, simply because he applied for a certificate of Mexican nationality while studying in Mexico. The United States was obliged to prove intent to relinquish citizenship by a preponderance of evidence (Vance v. Terrazas).
Since April 1990, the State Department has presumed that a U.S. citizen who naturalizes in another country intends to retain U.S. citizenship. Relinquishment, as distinct from renunciation, is a fairly simple procedure. But to meet the "preponderance of evidence of intent" provision, the State Department now imposes time-consuming and expensive barriers that discourage renunciation.
Nationality choice
In the meantime, since 1985, Japan has implemented a "National Choice" provision that requires Japanese who possess other nationals to declare, within 2 years after coming of age, their intention of remaining Japanese. The age of majority in 1985 was 20. It has been 18 since 2022, Those who become dual nationals after coming of age similarly must declare their choice of Japanese nationality within two years of their naturalization.
Contrary to its tag translation in English, the "nationality choice" (kokuseki sentaku 国籍選択) form is not a form for choosing a nationality. Rather it is a form for a Japanese national who possess other nationalities to notify (declare) ones intent to remain Japanese and relinquish the other nationalities.
The notifier is required to list the other nationalities, relinquish them to the Japanese government, and vow to endeavor to renounce them. The form is used by all dual nationals, regardless of how they became dual nationals, whether through birth, or through legal measures later in life.
Nationality through birth through birth is passive. Nationality acquisition later in life may also be passive, such as when acquired through marriage, or when naturalized by a parent or guardian. But most adult nationality acquisition -- usually in the form of naturalization -- is volitional.
When applying for permission to naturalize in Japan, a non-stateless alien generally vows to renounce ones nationalities -- not just to relinquish and endeavor to renounce, but to renounce, period. The "endeavor to renounce" phrasing n the national choice procedure appears to reflect a judicial understanding of the legal difficulties of enforcing hard-and-fast rules in a world in which all nationality laws are different, and Japan has no standing in how other states deal with dual nationality.
Nationality management
Given its national household register system -- administered not by the state or by prefectures, but by municipalities -- Japan could, but chooses not to, keep track of every Japanese person who is known to possess, or is thought to potentially possess, other nationalities.
Japan could, if it embraced the "exclusive citizenship" mindset of Senator Bernie Moreno, force compliance with a single-nationality scheme. But even in the computer age, enforcement would require considerable bureaucratic resources. Enforcement would also risk appearances of trampling on the rights of other states regarding how they treat nationals who happen to also be nationals of Japan -- not to mention the plausible rights of individuals to identify with and belong to more than one country.
One problem is that not all other states recognize choice of Japanese nationality as a cause for losing their nationality. Some countries even forbid renunciation, or make renunciation extremely difficult.
Japan fully understands that all nationality laws are different. It has a sovereign right to determine the standards for acquiring and losing Japan's nationality. But it also recognizes that other states have the same right regarding their nationality.
More importantly, though, despite popular claims to the contrary, Japan's Nationality Law has never prohibited dual nationality in principle. It has prevented it in some cases, discouraged it in others, and tolerated it when it is unable or unwilling to strictly eliminate it -- as in cases of multinational Japanese who for a variety of reasons have obtained and retained other nationalities.
The result is a gray zone that accepts dual nationality so long as it doesn't involve fraudulent behavior -- such as when, say, a dual Japan-U.S. national who enters Japan on a Japanese passport, and is thus Japanese, then uses his or her U.S. passport to get discounts or tax breaks intended for foreigners.
Moreno's bill
Bernie Moreno was not born a U.S. citizen. He immigrated to the United States from Columbia with his family when he was 5 years old. He grew up in Florida, and naturalized to the United States when he was 18 -- the youngest age possible.
Moreno's "Exclusive Citizenship Act" bill -- 119th Congress, Senate Bill 3283 -- is currently assigned to the Senate Judiciary Committee for review. Whether the committee approves it and passes it on to the Senate for deliberation and voting, remains to be seen. If passed by the Senate, it would go to the House of Representatives, and if passed there, it would go to the President, who could sign it into law or veto it.
Even if Moreno's bill manages to attract other sponsors, it faces numerous hurdles, especially in light of Supreme Court rulings that dual nationality -- if not exactly a right -- is not a cause for expatriation.
Last revised 30 December 2025