Dual nationality pros and cons
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.
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 passport status of 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.
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 (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 by 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 was not only harmless to a state's political integrity, but was generally beneficial for mixed-national families, which in turn were generally beneficial to the state. True, dual nationals are likely to encounter some positive and negative conflicts in 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.
"Nationality Choice" notification is specifically for the purpose of delcaring an intent to remain Japanese and relinquish other nationalities. The notification form requires that notifiers list their alien nationalities, relinguish them to the Japanese government, and vow to endeavor to renounce them. The same form is used for those by dual nationals who were born into dual nationaltiy, and those that became dual nationals through naturalization to Japan.
The latter, when naturalizing, generally vow to renounce their alien nationalities, not just relinquish adn endeavor to renounce. The ambiguity appears to be intentional on the part of Japan's law makers, who understand the legal diffculties of enforcing hard-and-fast rules in a world in which all nationality laws are different, and Japan has no standing in the nationality dispositions of other states. Japan would also have to keep track of dual nationals, and come up with ways to force compliance without trampling on the rights of other states, much less the rights of its own nationals.
One problem is that not all other countries recognize relinquishment to Japan as cause to lose their nationality. And some countries forbid renunciation, or make renunciation extremely difficult. Japan fully understands that all nationality laws are different. And just as Japan has a sovereign right to determine the standards for acquiring and losing its nationality, it has recognizes that it has no standing in the acquisition or loss of another state's nationality.
More importantly, despite a lot of popular claims to the contrary, Japan's Nationality Law has never explictly 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 legally expatriate dual national Japanese who for a variety of reasons have retained other nationalities.
The result is a gray zone that accepts dual nationality so long as it doesn't involve fradulent behavior -- such as a dual U.S.-Japan national who enters Japan on a Japanese passport, then uses his or her U.S. passport to get discounts or tax breaks intended for foreigners.
Japan-U.S.dual nationality originates several ways. The most common way is through birth in the United States to Japanese parents, or birth anywhere in the world to Japanese and American parents. The second most common path to dual Japan-U.S. nationality is through the naturalization of an American to Japan. Under Japanese law, Japanese who naturalize to the United States will lose their Japanese nationality.
Another way was that of my two children, were born before 1985, when Japan's Nationality Law became ambilineal -- meaning right-of-blood through either the mother or the father. I has previously been patrilineal if the father was Japanese, matrilineal if the mother was Japanese and unmarried, and right-of-soil for children born in Japan to unknown or stateless parents. My children, unable to become Japanese through their Japanese mother on account that was married to me, a U.S. citizen, became Americans through right-of-blood. The 1984 revision of the Nationality Law, effective from 1985, allowed children like mine, who resided in Japan, to acquire Japanese nationality through special measures effective through 1987.
Dual nationality also arises when a child is born in a jus soli (right-of-soil, place-of-birth) country to parents at least one of whom is a national of a jus sanguinis (right-of-blood) country. America's nationality law is also right-of-blood in the case of children born overseas to a U.S.-citizen parent. A child born in the United States to a Japanese national and a France-Burkina Faso dual national will potentially have 4 nationalities.
In the past, a child born in Japan to a Japanese national and national of the Republic of Korea, usually acquired its father's nationality. Today it stands to also acquire its mother's nationality. Both Japan and ROK now have nationality choice provisions. And both countries also recognize a declaration of choice of another nationality as cause to lose its nationality.
Best passport?
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.
At a press conferences promoting his bill, Moreno called U.S. passports the best in the world. What exactly he meant by this, he didn't elaborate. There are different criteria for determining what passports are the most valuable.
The most widely cited lists of "best passports" compare passports according to their value to travelers at ports of entry. Bearers of Singapore, Japanese, and several other passports are the most likely to be admitted to a country as tourists without visas.
Moreno is probably thinking that U.S. passports are the most coveted, because more people in other countries would like to reside in the United States -- not just travel or sojourn there, but settle. Whereas -- supposedly -- fewer people view Japan as a country in which they would like to live -- though there is no shortage of nationals in other Asian countries who would love to be able to work and even settle in Japan.
Last revised 29 December 2025