Sorry darlin’, McCain gets his citizenship via the Immigration and Nationality Act — “by statute”
Sec. 301. [8 U.S.C. 1401] The following shall be nationals and citizens of the United States at birth:
(c) a person born outside of the United States and its outlying possessions of parents both of whom are citizens of the United States and one of whom has had a residence in the United States or one of its outlying possessions, prior to the birth of such person;
Sec. 303. [8 U.S.C. 1403] Persons born in the Canal Zone or the Republic of Panama on or after February 26, 1904
(b) Any person born in the Republic of Panama on or after February 26, 1904, and whether before or after the effective date of this Act, whose father or mother or both at the time of the birth of such person was or is a citizen of the United States employed by the Government of the United States or by the Panama Railroad Company, or its successor in title, is declared to be a citizen of the United States.
And federal law trumps Vattel.
Notice it doesn't say WHICH type of citizen.
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And federal law trumps Vattel.
No, it does not.
But when I say that, in free states, the law of nations is the law of the people; I mean that, as the law of nature, in other words, as the will of nature's God, it is indispensably binding upon the people, in whom the sovereign power resides; and who are, consequently, under the most sacred obligations to exercise that power, or to delegate it to such as will exercise it, in a manner agreeable to those rules and maxims, which the law of nature prescribes to every state, for the happiness of each, and for the happiness of all.
Of the Law of Nations, James Wilson, Lectures on Law
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There is a natural and a positive law of nations. By the former, every state, in its relations with other states, is bound to conduct itself with justice, good faith, and benevolence; and this application of the law of nature has been called by Vattel, the necessary law of nations, because nations are bound by the law of nature to observe it; and it is termed by others, the internal law of nations, because it is obligatory upon them in point of conscience.
James Kent, Commentaries