What does it mean then? Enlighten us.
“Based upon the language of Article II, Section 1, Clause 4 and the guidance provided by Wong Kim Ark, we conclude that persons born within the borders of the United States are “natural born Citizens” for Article II, Section 1 purposes, regardless of the citizenship of their parents. Just as a person “born within the British dominions [was] a natural-born British subject” at the time of the framing of the U.S. Constitution, so too were those “born in the allegiance of the United States [] natural-born citizens.”
They based that on citations of historical English common law and discussions of a Supreme Court case. Perhaps the most too-the-point historical quotation is the following:
“It thus clearly appears that by the law of England for the last three centuries, beginning before the settlement of this country, and continuing to The present day, aliens, while residing in the dominions possessed by the crown of England, were within the allegiance, the obedience, the faith or loyalty, the protection, the power, and the jurisdiction of the English sovereign; and therefore every child born in England of alien parents was a natural-born subject, unless the child of an ambassador or other diplomatic agent of a foreign state, or of an alien enemy in hostile occupation of the place where the child was born.
III. The same rule was in force in all the English colonies upon this continent down to the time of the Declaration of Independence, and in the United States afterwards, and continued to prevail under the constitution as originally established.”
But that's just a court and, you know, judges. What could they possibly know about the law?