a. It has never been determined definitively by a court whether a person who acquired U.S. citizenship by birth abroad to U.S. citizens is a natural born citizen within the meaning of Article II of the Constitution and, therefore, eligible for the Presidency.
b. Section 1, Article II, of the Constitution states, in relevant part that “No Person except a natural born Citizen...shall be eligible for the Office of President;”
c. The Constitution does not define "natural born". The “Act to establish an Uniform Rule of Naturalization”, enacted March 26, 1790, (1 Stat. 103,104) provided that, “...the children of citizens of the United States, that may be born ... out of the limits of the United States, shall be considered as natural born citizens: Provided that the right of citizenship shall not descend to persons whose fathers have never been resident in the United States.”
d. This statute is no longer operative, however, and its formula is not included in modern nationality statutes. In any event, the fact that someone is a natural born citizen pursuant to a statute does not necessarily imply that he or she is such a citizen for Constitutional purposes.
But the distinction between classes of citizen only really matters for eligibility to the office of President. The Constitutional meaning has never been tested in Court, and this should not be surprising. There have not been many opportunities to hear such a case, and only one other were the person actually became President. But his disability, if he had one, was not discovered until well after he had left office. Chester Arthur did take measures to hide the fact that his father was not a US citizen at the time of his birth, although he was born in the US, and of a US Citizen mother... just like BHO may have been. But if BHO was not born in the US, but rather outside of it,then under the law in effect at the time, he wasn't even a "Citizen at Birth", which precludes him being a "natural born citizen". For being a citizen at birth is only a necessary condition for being a "Natural Born Citizen", not necessarily a sufficient one.