joining me now to talk about it, mary bridget mcmann and law professor at delaware law school. you for being with me. >> my pleasure. >> you wrote an op-ped, it got a whole lot of attention this week, an op-ped in the "washington post." you said donald trump is actually right about this but you also say i'm not a birther, but donald trump is right. explain. >> well, the constitution uses the term, or the phrase, natural-born citizen, as you said, and that comes from the common law. the supreme court has repeatedly said if you have a common-law term in the constitution, you have to look at the common law. when you go back and read the old common law, it's very clear a natural-born citizen is someone born in the territory of the sovereign. here the united states. >> i spoke to addam winkler at u ucla, his argument is you're a natural-born citizen if you're a citizen at birth. here's what we know about ted cruz. yes, he was born in canada. his mother an american citizen. let's play what adam said. >> i think there's no doubt he is eligible to be president. the constitution says yo