Ted Cruz was born in Calgary, Canada.

[Jim Lane]

37. It's a bit different from what you've said.

At the time of Obama's birth, and at the time of Cruz's birth, the law concerning a child born abroad to one citizen parent and one noncitizen parent was that the citizen parent transmitted citizenship to the kid automatically, provided certain conditions were met. One condition was that the citizen parent had to have lived in the United States for at least five years after having attained the age of fourteen.

As a matter of math, no citizen parent under the age of nineteen could meet this condition. Obama's mother was eighteen when he was born. Therefore, if he had been born in Kenya, he wouldn't have been a citizen.

It doesn't directly relate to the age of the citizen parent. Even a much older citizen parent wouldn't have transmitted citizenship if he or she had left the United States early in life and spent so much time abroad that he or she didn't meet the requirement of living here for five years after turning fourteen.

Cruz's mother, however, was no teenager, and easily met the five-year requirement. Therefore, Cruz was a citizen at birth and is eligible to be President.

Obama is eligible for a different reason -- a child born in the U.S. is a citizen unless entitled to diplomatic immunity at birth. The parents' citizenship is immaterial.

As for children born abroad, the five-year requirement has since been abolished. That doesn't moot the whole Kenya sideshow, though. The phrase "natural born citizen" isn't defined in the Constitution, so I think the obvious meaning is that the kid was a citizen at birth, without needing subsequent legislation or a naturalization proceeding. Therefore, a prospective President's eligibility must be assessed in light of the law in effect at the time of his or her birth.