Like me, you see, John McCain was not a U.S. citizen at birth. This paper by Gabriel Chin - Why Senator John McCain Cannot Be President: Eleven Months and a Hundred Yards Short of Citizenship - argues that McCain is ineligible, and explains why he was not born a citizen (contra, apparently, remarks that the author made to a reporter a few months ago).
McCain was born in the Panama Canal zone in 1936. Chin explains that the zone was not incorporated into the U.S. as a territory, but was subject to U.S. jurisdiction. The fact that it was not an incorporated territory meant that people born there, unlike in U.S. states or incorporated territories like Puerto Rico, were not automatically granted citizenship based on place of birth.
A law which took effect in 1934 conferred citizenship on “[a]ny child hereafter born out of the limits and jurisdiction of the United States, whose father or mother or both at the time of the birth of such child is a citizen of the United States.” McCain's parents were U.S. citizens, but the Canal Zone was not outside of the jurisdiction of the United States, since the U.S. exercised sovereignty over it. Hence the 100 yards in the paper's title; had McCain's mother given birth 100 yards away in Panamanian territory, McCain would have been a citizen under this law.
Congress fixed the law in 1937 - 11 months after McCain came along - so that children born to U.S. citizens in the Canal Zone would be born citizens. It applied retroactively, conferring citizenship on McCain and many others like him.
So McCain was not born a U.S. citizen, but he is a U.S. citizen by virtue of the circumstances of his birth. Here's the issue: is he a "natural born citizen" in the meaning of Article II of the Constitution, which requires the president to be a natural born citizen?
Prof. Solum comments that legal history leaves it unclear which of the following two readings is appropriate.
(1) The at-birth reading. One interpretation of the clause is that "natural born citizens" are persons who citizenship existed at the moment of birth. If we assume Chin is correct re the minning of Section 1993, then the at-birth reading implies that McCain is not a natural born citizen.
(2) The by-birth reading. There is, however, another possible interpretation or construction of the clause: the clause might mean that "natural born citizens" are persons who are citizens by virtue of circumstances of their birth. McCain is a citizen by virtue of the fact that he was born to American citizens in the Panama Canal Zone, and hence, he is an American citizen by virtue of the circumstances of his birth.
If the second reading is correct, then my dream of becoming president is alive. It would not require a constitutional amendment. It could simply be done by getting Congress to pass a law conferring citizenship retroactively on all people born in Jewish General Hospital in Montreal on the evening of Sept. 24, 1975. Arnold Schwarzenegger could be president if congress grants citizenship to all people born in Thal, Austria on July 30, 1947. That's one reason to think the second reading is not the right one - it allows Congress to circumvent a constitutional restriction and "opt-in" any candidate it chooses to, using a highly selective conferral of citizenship based on birth.
Another reason to adopt the first reading is a little more linguistic. Natural clearly has a special meaning in this context. The term seems to cover exactly the set of U.S. citizens. U.S. citizens who were not born U.S. citizens were naturalized - they underwent a change of status from not being natural in the special sense, to being natural. So the most straightforward way to understand natural born citizen is as the set of citizens that were not naturalized, i.e. the set of citizens who were born citizens. Natural-born makes up a linguistic unit just like high-born does. It makes for a parsimonious partition in the set of U.S. citizens.
Unfortunately for parsimony, but fortunately for me, McCain and Arnie, these terms have not been interpreted in this straightforward way. Chin cites Jill A. Pryor for the proposition that individuals who are born U.S. citizens pursuant to congressional authority, such as those born to U.S. citizen parents outside the U.S., are legally considered to be both naturalized citizens and natural-born citizens. Still, one would think that a textualist who prefers parsimony over judicial precedent for interpretation - like, say, Justice Scalia in Heller - would favor a good linguistic analysis in his interpretation of the text, no?