It is not settled law. If it were, Obama wouldn’t be in the WH.
"At common-law, with the nomenclature of which the framers of the Constitution were familiar, it was never doubted that all children born in a country of parents who were its citizens became themselves, upon their birth, citizens also. These were natives, or natural-born citizens,"in Minor v. Happersett (1875)
Without first coming to that determination, the court could not have determined if Virginia Minor was a "citizen" who had the right to vote.
The reason Barry sites in the Oval office today, is not due to not knowing who a "natural born Citizen" is...but rather, due to fear and political expediency. Nobody in a position of power to do anything wanted to rock the boat on the first (half) "black" President, potentially loosing their job, their broadcasting license or worse. It became the 3rd rail.
“Settled law”? Wow, that’s almost as meaningless a phrase as “settled science”. Law and science will never be settled, it is their nature.