Children born in the United States to parents unlawfully or temporarily present are not 'subject to the jurisdiction' of the United States and thus not citizens at birth under the Fourteenth Amendment.

1) The question is whether children born in the United States to parents who are unlawfully present or only temporarily present (e.g., tourists, students) acquire citizenship at birth under the Fourteenth Amendment's Citizenship Clause. 2) The relevant constitutional text is: 'All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.' The key phrase is 'subject to the jurisdiction thereof.' 3) At the time of ratification, the phrase 'subject to the jurisdiction' meant being under the complete political authority and allegiance of the United States, not merely present within its territory. The common law rule of jus soli had exceptions: children of foreign sovereigns and their ministers, children born on foreign public ships, and children of Indian tribes not taxed. These exceptions show that territorial birth alone was insufficient; the child must not owe allegiance to any other sovereign. The legislative history of the Civil Rights Act of 1866 and the Fourteenth Amendment confirms that the amendment was primarily intended to grant citizenship to freed slaves, not to children of foreigners who retained allegiance to their home countries. 4) The holding: The Citizenship Clause does not grant birthright citizenship to children born in the United States to parents who are unlawfully present or only temporarily present in the country. Such children are not 'subject to the jurisdiction' of the United States because their parents owe allegiance to a foreign power and the child's own political status is derivative or incomplete at birth. Congress, under its naturalization power, may choose to grant citizenship to such children by statute, but the Constitution does not require it. 5) Downstream, this means that Executive Order 14160, which denies citizenship to these children, is consistent with the original meaning of the Fourteenth Amendment. The lower court's injunction is vacated, and the case is remanded for further proceedings consistent with this opinion.