At Kawakita's trial, presided over by U.S. District Judge William C. Mathes, the defense conceded that Kawakita had acted abusively toward American POWs, but argued that his actions were relatively minor, and that in any event, they could not constitute treason against the United States because Kawakita was not a U.S. citizen at the time, having lost his U.S. citizenship when he confirmed his Japanese nationality in 1943. The prosecution argued that Kawakita had known he was still a U.S. citizen and still owed allegiance to the country of his birth—citing the statements he had made to consular officials when applying for a new passport as evidence that he had never intended to give up his U.S. citizenship.