“Which may or may not make a difference depending on the law then in effect.”
It makes not a lick of difference. McCain is a natural born citizen no matter where he was born, via 1790 law.
So is Barack Obama btw (see other post), via 1952 and 1934 law.
The law had been changed by the time McCain was born.
That said, the 1790 law does give insight into what the authors of the Constitution meant by "natural born citizen". However, IIRC, that law only provided for the case of the father being a US citizen, as was common in the laws of other countries at the time (1790). So that law, if it applied, which it can't directly because Congress cannot define the meaning of terms in the Constitution, else they could change the meaning of "keep and bear" to mean strictly in a state militia context by a simple law, which would override the meaning understood at the time. Just as the later immigration laws could change the definition of "natural born citizen" from that understood by the authors and ratifiers of the Constitution. Under the law in effect at the time, if BHO was born overseas of a legally unwed mother, who had not lived in the US for 5 years after her 14th (or 16th I can't remember which was in effect in '61) then he would not be a "natural born" citizen, even though he could have been sponsored for citizenship by citizen ship by his mother, a US citizen, or could have been fraudulently registered as having been born in the US. We don't know enough yet to know which it is.
What I'd like is for both Obama and McCain to be declared ineligible, and then we'd get a really weird "do over" of a really weird primary election season. But I don't expect to get that.