8 USC § 1401 - Nationals and citizens of United States at birth:
The following shall be nationals and citizens of the United States at birth:
(d) a person born outside of the United States and its outlying possessions of parents one of whom is a citizen of the United States who has been physically present in the United States or one of its outlying possessions for a continuous period of one year prior to the birth of such person, and the other of whom is a national, but not a citizen of the United States.
"In any event, the fact that someone is a natural born citizen pursuant to a statute does not necessarily imply that he or she is such a citizen for Constitutional purposes."
http://www.state.gov/documents/organization/86757.pdf
Statutory citizenship does not automatically render one Constitutionally eligible for president.
“does not necessarily imply “
Meaning that it also does not imply the converse, either, that a statute does not guarantee citizenship for constitutional purposes, either. This is a State Department document, not one of controlling legal authority. It was written by a State Department employee. That was a lawyer statement claiming that other controlling legal authorities settle the matter and not that document.