In Wong Kim Ark v. United States (1898), the Supreme Court held that the 14th Amendment conferred citizenship on anyone born here, except for children of foreign diplomats (who had diplomatic immunity, and thus were not subject to the jurisdiction of the U.S.) and American Indians born in those parts of Indian country which were still sovereign and had not been subjected to U.S. law.
Read on, there's more:
"But the children, born within the realm, of foreign ambassadors, or the children of alien enemies, born during and within their hostile occupation of part of the king's dominions, were not natural-born subjects, because not born within the allegiance, the obedience, or the power, or, as would be said at this day, within the jurisdiction, of the king.
This leads to the question of whether or not being in the US "without the Kings permission" or "hostile to the laws of the jurisdiction", does by law enable the offspring of those in the US illegally with the right, under the 14th. Amendment, to claim citizenship by birth. Yes I know it's the custom, but is it really the law.