The US Supreme Court has already cited the definition of 'natural born Citizen'in five separate cases. The Supreme Court of the United States has never applied the term “natural born citizen” to any other category than “those born in the country of parents who are citizens thereof”.
Obama wasn't challenged by congress because the republicans were too scared of the leftist media calling them racist. That trumped their duty to uphold their sworn oath to protect the Constitution.
5 times? When was the last one?
Five times? When was the first one?