If we admit that there are exceptions, then how is it determined which exceptions are or aren't constitutional?
I don't think you need to look beyond the Framers’ intent in regards to the Citizen Clause of the 14th Amendment. The author was Senator Jacob M. Howard and the Framers’ intent can be determined by reading the debate.
The understanding was that foreigners, aliens, Indians and ambassadors aren't citizens by being born on US soil. That status is determined by the status of the parents, obviously.
"Why are children of ambassadors and diplomats not natural-born citizens if they are born on US soil? It's not the child's fault who his parents are."It's not an issue of fairness. It's an issue of English common law. Ambassadors are under the leigeship of a foreign government. Their bodies and households are foreign soil. For that reason, foreign consulates are considered foreign territory. So a child of an ambassador is born in the land of its parent wherever that birth takes place. Beyond that, the status of the parents make no difference.*
* A possible exception might be if BOTH the parents were in the US illegally. But the issue has never come up in an elected POTUS, so who knows? As it is, the congress treats children born in the US to illegals as (at the very least) NATURALIZED citizens, and the Constitution gives them the right to determine the qualifications of naturalization.
I don't think you need to look beyond the Framers’ intent in regards to the Citizen Clause of the 14th Amendment.That debate was not participated in by the Founders. Nor does a debate hold the force of law. "US v Wong Kim Ark" does have the force of law.