Who is a "natural born citizen" of the United States?

Birthers questioned whether Obama was in fact born in the United States, while they claim Rubio, indisputably born in Miami, is not eligible because his parents were not citizens at the time of his birth

writes Byron York regarding birther talk (thanks to InstaPundit) and the legal aspect thereof. (See my in-depth and dispassionate analysis of the birther controversy: The JournoList Issue No One Is Bringing Up.)

The one thing that characterizes both arguments is an ignorance of the law concerning citizenship.

The Constitution specifies that a president must be a "natural born citizen" of the United States, but it does not define the term. The Supreme Court has never clarified the issue, but there is a law, 8 U.S. Code 1401, that spells out in detail who is a citizen.

The law uses the phrase "citizens of the United States at birth" and lists categories of people who fit that description.

First, there are people born inside the United States. No question about that; their citizenship is established by the 14th Amendment.

Then there are the people who are born outside the United States to parents who are both American citizens, provided one of them has lived in the U.S. for any period of time. And then there are the people who are born outside the United States to one parent who is a U.S. citizen and the other who is an alien, provided the citizen parent lived in the United States or its possessions for at least five years, at least two of them after age 14.

Since they are all "citizens of the United States at birth," the question is, does that also mean they are "natural born citizens" in the constitutional sense?

"My conclusion would be that if you are a citizen as a consequence of your birth, that's a natural-born citizen," says Theodore Olson, the former Bush solicitor general who defended John McCain in a 2008 lawsuit alleging McCain was ineligible to be president. McCain was born in the Panama Canal Zone in 1936 while his father served in the U.S. Navy there. Even though the area was under American jurisdiction and both McCain's parents were U.S. citizens, some Democrats alleged McCain was ineligible to be president. McCain won the case, if not the presidency.

The law is really quite lenient, especially for those born outside the United States. If a child were born today in, say, Kenya, to a Kenyan father and an American citizen mother who had lived in the United States for at least five years, at least two of them over the age of 14 -- that child would be a "citizen of the United States by birth" and be eligible for the White House.

But what about Rubio? What about a child born in the United States to noncitizen parents? "I am not aware of anyone who has contended that someone could be born in the United States and be a citizen by virtue of the 14th Amendment and nevertheless still not be a natural-born American citizen," says Washington lawyer Matthew McGill, who worked with Olson on the McCain case and did extensive research into the law and history of citizenship. "If he is born in the United States, his parentage is not of consequence."

But some do contend that Rubio is not eligible for the presidency. (The eligibility requirement for vice president is the same as president.) "Rubio is, quite simply, not a 'natural born citizen' by the accepted legal, English-language standard as it has been known throughout American history," wrote WorldNetDaily founder and editor Joseph Farah in February. "He was born in Florida to two non-U.S. citizen parents."

But according to the law, Rubio is a "citizen at birth," and the most reasonable reading of the law and the Constitution is that an American is a natural-born citizen if he or she is a citizen at birth. There might be complaints about that in coming months, but that's the way it is.