On qualifying for Presidency [link]
Article Two of the Constitution sets the principal qualifications to be eligible for election as President. A Presidential candidate must:
* be a natural-born citizen of the United States;
* be at least thirty-five years old;
* have been a permanent resident in the United States for at least fourteen years.
Additionally, the Constitution disqualifies some people from the Presidency. Under Article One of the United States Constitution, the Senate has the option, upon conviction, of disqualifying impeached individuals from holding other federal offices, including the Presidency.[4] Under the Twenty-Second Amendment, no one can be elected President more than twice. The Twenty-Second Amendment also specifies that anyone who serves more than two years as President or Acting President, of a term for which someone else was elected President, can only be elected President once. Under the Twelfth Amendment a person who is no longer eligible to be President may not be Vice President either.
Foreign-born Americans at the time the Constitution was adopted were also eligible to become President, provided they met the age and residency requirements.
On the definition of "natural-born citizen" [link]
All persons born in the United States, except those not subject to the jurisdiction of the U.S. government (such as children of foreign diplomats) are citizens under the Fourteenth Amendment. Persons born in the United States, and persons born on foreign soil to two U.S. parents, are born American citizens and are classified as citizens at birth under 8 USC 1401. There is some debate over whether persons who were born US citizens and are classified as citizens at birth under U.S. law should also be considered citizens "by birth," whether they should all be considered to be "naturalized," or whether they should be considered "statutory citizens." There is also some debate over whether there is a meaningful legal distinction between citizens "at birth", citizens "by birth" and "statutory citizens" since U.S. law makes no such distinction, nor does the Fourteenth Amendment use the term "at birth." Current U.S. statutes define certain individuals born overseas as "citizens at birth."[18] One side of the argument interprets the Constitution as meaning that a person either is born in the United States or is a naturalized citizen. According to this view, in order to be a "natural born citizen," a person must be born in the United States, or possibly an incorporated territory; otherwise, they are a citizen "by law" and are therefore a "statutory citizen," (not necessarily, however, a naturalized citizen, which implies a pre-existing foreign citizenship).[2] Current State Department policy reads: "Despite widespread popular belief, U.S. military installations abroad and U.S. diplomatic or consular facilities are not part of the United States within the meaning of the 14th Amendment. A child born on the premises of such a facility is not subject to the jurisdiction of the United States and does not acquire U.S. citizenship by reason of birth."[19] However, the State Department is of the opinion that this does not affect those who are born abroad to U.S. citizens and who otherwise meet the qualifications for statutory citizenship.[20]