I believe Obama’s own “fight the smears” website said he was eligible for British citizenship at birth, and for Kenyan citizenship if he applied at age 18. I myself was not eligible for either, and I suspect a lot of other Americans were not by birth. I think the answer to the trivia question “who was the last US president born a British subject is arguably answered correctly by pointing to Barack Obama.
I am only stating my opinion as to what I believe the law should be. I also believe, perhaps incorrectly, that dual citizenship is a relatively recent concept.
Just my two cents.
All persons born in the allegiance of the King are natural-born subjects, and all persons bornin the allegiance of the United States are natural born citizens. Birth and allegiance gotogether. Such is the rule of the common law, and it is the common law of this country, as well as in England.
This is taken from U.S. v Rhodes (a circuit court decision), but in that decision, this passage is summarizing dicta in Shanks v. Dupont, an 1830 SCOTUS case. That case said:
The Treaty of 1783 acted upon the state of things as it existed at that period. It took the actual state of things as its basis. All those, whether natives or otherwise, who then adhered to the American states were virtually absolved from all allegiance to the British Crown; all those who then adhered to the British Crown were deemed and held subjects of that Crown.
When it says "natives or otherwises," the natives refers to people born on U.S. soil. Depending on the political allegiance of the parents, you could be born on U.S. soil and be a British citizen, not a U.S. citizen. It says if you "adhered" to the Crown, you were a British subject ... native or otherwise (born in the U.S. or not). The key factor isn't jus soli, it's jus sanguinis. If we are to accept a common-law definition of NBC, the key factor is jus sanguinis.
The other problem is that the common law in England required the parents to have "actual obedience" to the crown. There's no American concept analogous to this. Second, English common law did not respect dual allegiances. You had solitary allegiance to the crown and it was perpetual allegiance. By citing the passages above, with reference to the Treaty of 1783, it is saying you cannot be a dual citizen. You are either one or the other. Your allegiance (through the parents ) is either to the crown and you are a subject, or you're allegiance is to the United States and you are a natural-born citizen by birth. It doesn't accept a combination of allegiances. Obama's father never had allegiance to the United States. His mother's allegiance is irrelevant, because a natural-born citizen cannot be a dual citizen by the terms of this treaty. It explains why Gray used common law, but NOT the term natural-born citizen, to declare Wong Kim Ark to be a citizen by birth. What he did require, however, was permanent residence and domicil, neither of which that Obama's parents had.