343 U.S. 717 (1952
Kawakita was an important United States Supreme Court case regarding dual citizenship. The petitioner, Tomoya Kawakita, was born in the United States to Japanese parents, and returned to Japan in 1939. He initially registered as an American citizen with the consulate in Tokyo, but after graduating from college in 1943, he registered in his Japanese family's koseki and took a job as an interpreter, where his job was to intercept communications coming in and out of prisoner of war facilities.
In 1945, after Japan's surrender, Kawakita applied for a new American passport and returned to the United States, where he was convicted of treason and sentenced to death.
Kawakita appealed the claim, saying that he lost his American citizenship when he established his Japanese residency (see: How to become Japanese), and that the treason charge was invalid because he was not an American citizen at the time of the crime. He cited his koseki registration and his work with the Japanese military as evidence that he had forfeited his American citizenship. The appeal made its way to the Supreme Court by writ of certiorari.
The Supreme Court issued its ruling on June 2, 1952. Justice William O. Douglas delivered the opinion. He argued that, since Kawakita had not made any explicit oath of naturalization (he was already a citizen) or explicitly enlisted in the Japanese military, he had not forfeited his American citizenship. The conviction was affirmed by a 7-0 ruling (two justices were absent).
Despite the conviction, President Dwight D. Eisenhower stayed Kawakita's death sentence, had his American citizenship revoked, and deported him to Japan. So in a way, Kawakita ended up getting exactly what he had asked for.