Jonathan Adler writes at The Washington Post:
Donald Trump has recently begun to raise questions about whether Sen. Ted Cruz (R-Tex.) is constitutionally eligible to be president of the United States. Specifically, Trump has revived concerns that Cruz is not a “natural born citizen” under the Constitution. While stopping short of claiming Cruz is ineligible, Trump suggests that litigation over Cruz’s eligibility could be a problem. These concerns are misplaced.
Article II, section 1 of the Constitution provides:
No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution,shall be eligible to the Office of President; neither shall any Person be eligible to that Office who shall not have attained to the Age of thirty five Years, and been fourteen Years a Resident within the United States. (emphasis added)
Ted Cruz was born in Canada. His mother was a U.S. citizen. His father, a Cuban, was not. Under U.S. law, the fact that Cruz was born to a U.S. citizen mother makes him a citizen from birth. In other words, he is a “natural born citizen” (as opposed to a naturalized citizen) and is constitutionally eligible.
Neal Katyal & Paul Clement write at
The Harvard Law Review:
While some constitutional issues are truly difficult, with framing-era sources either nonexistent or contradictory, here, the relevant materials clearly indicate that a “natural born Citizen” means a citizen from birth with no need to go through naturalization proceedings. The Supreme Court has long recognized that two particularly useful sources in understanding constitutional terms are British common law (See Smith v. Alabama, 124 U.S. 465, 478 (1888)) and enactments of the First Congress. (See Wisconsin v. Pelican Ins. Co., 127 U.S. 265, 297 (1888).) Both confirm that the original meaning of the phrase “natural born Citizen” includes persons born abroad who are citizens from birth based on the citizenship of a parent.
...
Despite the happenstance of a birth across the border, there is no question that Senator Cruz has been a citizen from birth and is thus a “natural born Citizen” within the meaning of the Constitution. Indeed, because his father had also been resident in the United States, Senator Cruz would have been a “natural born Citizen” even under the Naturalization Act of 1790.
