The Supreme Court case Fok Young Yo v. United States was about the power of the federal government to exclude or expel aliens. The petitioner, Fok Young Yo, was a citizen of the Empire of China and a resident of Guatemala who was seeking a writ of habeas corpus from the district court in the northern district of California. Fok Young Yo claimed that he was unlawfully detained by the United States government and prevented from entering the country.
The Supreme Court ruled that the power to exclude or expel aliens is vested in the political branches of the government, to be regulated by treaty or act of Congress and executed by the executive authority. The Court found that the decision of the collector of customs on Fok Young Yo's right to transit across the United States was conclusive, and that the government had the authority to deny his entry into the country. This case affirmed the broad powers of the federal government in controlling immigration and the entry of non-citizens into the United States.