Media reports about lawmaker Renhō’s dual nationality and a court case involving loss of citizenship have drawn renewed attention to nationality-related matters in Japan recently. The emergence of dual nationality as an issue is closely related to the requirement under Japan’s Nationality Act that children of international marriages who have both Japanese and other citizenships must choose between them before they reach age 22.

Japan’s Progressive Nineteenth-Century Nationality Act

Modern Japan’s earliest legislation regarding citizenship was in the form of a cabinet declaration issued in 1873 governing the status of women entering into international marriages—Japanese women who married foreign men and foreign women who married Japanese men. The declaration imposed a requirement on Japanese citizens entering into international marriages to receive government permission. The provision applied to all those whose names were recorded in the official family registers that had been introduced in 1872—in other words, it considered such people to be Japanese citizens. This cabinet declaration established the first official link between Japanese citizenship and the family registration system. Japan’s first positive law about citizenship was the Nationality Act of 1899, but the country had already introduced the modern concept of citizenship as part of its legal system a quarter century before that.

It is interesting to note that the introduction of the concept of citizenship under the 1873 cabinet declaration was a result of contact with other countries. The same can be said for the 1899 Nationality Act. This law was quite progressive for its time, notably in its recognition of loss of citizenship. In nineteenth-century European countries, military service was mandatory for all male citizens, and it was normal for governments to place strict conditions on the acquisition of other nationalities by those who had served, lest they reveal military secrets. But from the start Japan’s legislation allowed Japanese to naturalize as citizens of other countries. The basic principle was that women entering into international marriages were to assume the same nationality as their husbands —"one couple, one nationality.” And this nationality was passed on to any children they had. So it was also a principle of “one family, one nationality.”

The motivation behind these provisions was not to force the assimilation of foreigners who married into Japanese families. The background was the situation in Europe, where members of the same family who had different nationalities sometimes found themselves fighting on opposite sides in a war. Japan’s nationality law sought to prevent this from happening as a humanitarian consideration. And the adoption of this humanitarian consideration—which was advanced for its time—was part of an overall drive to show that Japan was a “civilized” country and thereby to win the repeal of the various unequal treaties that it had been forced to accept when opening itself to the outside world in the mid-nineteenth century. Securing repeal of these treaties was a major priority for the Japanese government in the latter part of the century.

Revisions over the Years

The 1899 Nationality Act adopted the principle of jus sanguinis, meaning that the nationality of children was determined by that of their parents—not by where they were born (jus soli). Here I would like to refer to the cases of Japanese emigrants to Brazil and their offspring, a group on which I have done research. Starting in 1908, many Japanese migrated to Brazil in groups and together established colônias (colonies), which they referred to as “Japanese communities”—not “Japanese-Brazilian communities.” Under the 1899 law, their children born in Brazil were also Japanese citizens. (Actually this jus sanguinis provision applied only to children whose fathers were Japanese. As noted above, Japanese women who married foreigners took their husband’s nationality, so their children did not have Japanese citizenship.)

This late-nineteenth-century legislation remained in effect until after the end of World War II. But in 1950 it was replaced with the current Nationality Act, which modified the application of the jus sanguinis provision. Under the 1950 legislation, children born to Japanese fathers outside of Japan acquired Japanese citizenship not automatically by birth but only through the submission of specified documents to the relevant Japanese authorities, such as a local consular official. And in 1985, when Japan ratified the Convention on the Elimination of All Forms of Discrimination Against Women, it also became possible for Japanese women in international marriages to pass their nationality on to their children, a right that had previously been limited to men. So the rules governing who is a Japanese citizen have been modified over the course of the years.

Japan’s rejection of dual citizenship is not based on nationalism. It was intended to avoid the sort of splits within families that had occurred in Europe, as I noted above. The idea was that it was best for those concerned to belong to a single country. This led to the adoption of the “one family, one nationality” principle. The rejection of dual citizenship was thus motivated by humanitarian concerns. And we should also keep in mind that it was grounded in the international situation at the time the 1899 law was adopted.

Emigrants Who Had to Relinquish Their Japanese Citizenship

In practice, however, the ban on dual nationality ended up constantly causing problems for emigrants from Japan. These emerged when emigrants who had been employed as laborers in their new countries became ready to move on to a new stage. After working for a number of years and accumulating some savings, an emigrant might want to become the owner of a farm or business. This is where citizenship often became an issue, both in the United States and in South American countries like Brazil and Peru. Many emigrants needed to naturalize so as to advance their status, but doing so meant giving up their Japanese citizenship.

After World War II, additional Japanese emigrated to Latin America, and in many cases they had to naturalize in order to hold ownership of their farmland or to assume posts of a certain status in companies or agricultural cooperatives. Over the past two decades I have been hearing stories from emigrants to Brazil who explain that they gave up their Japanese citizenship not because they wanted to but because they had to in order to hold on to their assets, and who say that even now they would like to be recognized as Japanese citizens.

Foreigners living in Japan sometimes run into the same need to change their nationality for professional reasons. For example, the Mining Act prohibits foreigners from owning mines, and foreigners cannot become civil servants. And until just a few years ago, foreign wives of Japanese diplomats were required to naturalize in order to accompany their husbands on overseas postings.