Why Scholars Say Cruz Is Eligible for Presidency

Donald Trump says questions about whether Ted Cruz is eligible to be President of the United States could become a "big problem" for the Canadian-born Republican candidate. But among legal scholars, there's a consensus: He's eligible to occupy the Oval Office.

The Texas senator, who was born in Calgary, Canada, to an American mother, has been widely viewed as meeting the "natural born citizen" requirement of the United States Constitution. And most legal experts agree -- including former Solicitors General Neal Katyal and Paul Clement.

"An individual born to a U.S. citizen parent -- whether in California or Canada or the Canal Zone -- is a U.S. citizen from birth and is fully eligible to serve as President," the bipartisan duo wrote in a Harvard Law Review article in March 2015. Trump first raised this question of President Obama in 2008, saying that the future president, who was born in Hawaii, may not be eligible.

Laurence Tribe, a professor at Harvard Law School, told ABC News that Trump's alternative definition would mean that only citizens born in the United States would be eligible.

"My own view as a constitutional scholar is that the better view -- the one most consistent with the entire Constitution -- is the broader definition, according to which Cruz would be eligible," he said, including anyone who is a U.S. citizen at birth and doesn't need to be naturalized.

Burt Neuborne, a professor at New York University Law School, agreed: "It seems to me that his citizenship is just as good as Donald Trump's citizenship."

Facing questions about his nationality before he announced his candidacy for president, Cruz took the unusual step in June 2014 of formally renouncing his Canadian citizenship. Cruz said today on the campaign trail that the question is "settled law." But most scholars agree that the question has not yet been officially resolved.

"I think there's a scholarly consensus, but it's not a done deal," said Sarah Helene Duggin, a professor at the Catholic University of America, adding that experts aren't unanimous on the issue. "I don't think it's open and shut at all."

Tribe, who also taught constitutional law to Cruz and Obama at Harvard, concurred. "I don't agree that it's 'settled law,'" he told ABC News. "The Supreme Court has never addressed the issue one way or the other, as I believe Ted ought to know."

Trump also says that the question could prompt a long, drawn-out battle in the courts that could spell problems for the Republican Party. But Neuborne disagrees.

"You're putting the presidency in play in some way in a world in which the American president is the anchor," Neuborne said. "When that is threatened, the American judiciary moves immediately and fast."