In Article 2 of the US Constitution, it states ‘No person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President…’
Notice that there’s a comma after the word ‘Citizen’ and after the word ‘States’. It doesn’t say ‘No person except a natural born Citizen or a Citizen of the United States at the time of…’ but adds two commas. Could this be finagled to allow Arnie - or equally Madeleine Albright - to be POTUS?
Commas are an issue of constant Constitutional consternation, but in this case, I don’t see how such an argument could be finagled, since separating “or a Citizen of the United States” from “at the time of the Adoption of this Constitution” would leave the latter clause dangling off a cliff, and that would make no sense. IOW, If that clause did not modify the one before it, it would have nothing to modify.
The alternative would be for “at the time of the adoption of this Constitution” to modify both of the preceding clauses, in which case nobody alive today is eligible to be President, in an Anarchist Wet Dream.
Not only that; this interpretation would also make the “natural born Citizen” clause pointless. If “a Citizen of the United States” is taken to stand alone, without the modifier, then everybody who falls under the “natural born Citizen” clause will also fall under the “Citizen of the United States” clause. The former one would lose its significance entirely. The conventional interpretation that you have to be either (1) a natural born citizen or (2) a citizen at the time of the adoption of the Constitution is the only one which makes sense, both grammatically and with regards to content, and thus should be preferred.