United States v. Wong Kim Ark - Wikipedia
United States v. Wong Kim Ark, 169 U.S. 649 (1898), was a landmark decision of the U.S. Supreme Court which held that "a child born in the United States, of parents of Chinese descent, who, at the time of his birth, are subjects of the Emperor of China, but have a permanent domicil and residence in the United States, and are there carrying on business, and are not employed in any diplomatic or official capacity under the Emperor of China", automatically became a U.S. citizen at birth. This decision established an important precedent in its interpretation of the Citizenship Clause of the Fourteenth Amendment to the Constitution. Any child born in the United States is a US citizen from birth, with the sole exception of children born to a parent or parents with diplomatic immunity, since such parent is not a "subject to the US law" as the decision requires.