Changes the rule for who is a U.S. citizen at birth by narrowing when a person born in the United States is considered “subject to the jurisdiction” of the United States. Under the change, a person born in the U.S. is a citizen at birth only if at least one parent is a U.S. citizen or national, a lawful permanent resident who resides in the U.S., or an alien lawfully serving in the U.S. armed forces. The change does not affect anyone born before the law takes effect.