According to
Natural born citizen | Wex Legal Dictionary / Encyclopedia | LII / Legal Information Institute
"
Consensus exists that anyone born on U.S. soil is a "natural born Citizen." One may also be a "natural born Citizen" if, despite a birth on foreign soil, U.S. citizenship immediately passes from the person's parents."
Section 5 of the 14th Amendment says:
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The Congress shall have power to enforce, by appropriate legislation, the provisions of this article"
Article 1, Section 8, Clause 4 of the US Constitution says that Congress has authority to create law regarding naturalization which includes citizenship.
So who can be considered a natural born citizen is kind of vague, legally speaking. Congress says, under Title 8 of the US Code, Section 1401 defines natural born citizens as:
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Anyone born inside the United States. The person must be “subject to the jurisdiction” of the United States. (This would exempt the child of a diplomat, for example, from this provision.)
Any Indian or Eskimo born in the United States, provided being a citizen of the U.S. does not impair the person’s status as a citizen of the tribe
Any one born outside the United States, both of whose parents are citizens of the U.S., as long as one parent has lived in the U.S.
Any one born outside the United States, if one parent is a citizen and lived in the U.S. for at least one year and the other parent is a U.S. national
Any one born in a U.S. possession, if one parent is a citizen and lived in the U.S. for at least one year
Any one found in the U.S. under the age of five, whose parentage cannot be determined, as long as proof of non-citizenship is not provided by age 21
Any one born outside the United States, if one parent is an alien and as long as the other parent is a citizen of the U.S. who lived in the U.S. for at least five years (with military and diplomatic service included in this time)"
(source :
Defining "Natural Born Citizen" | IVN.us)
Chances are, McCain is easily eligible to be president.