The Constitution requires that the President be a "natural born citizen." The Founders understood this to be only someone born in the United States. Children of American parents born overseas were not citizens at birth, but had to come to the United States to be "naturalized." This reflected traditional notions of law, inherited from England, that (with the exception of the children of diplomats and sometimes others in direct service of the Crown), birthplace determined citizenship and obligations. Thus, after American independence, the child of an American born in England was considered a citizen of England by both countries. Similarly, the child of citizens of Great Britain born in the United States was considered a citizen of the United States.
The Founders applied this concept to the presidency, because they feared that someone born outside the US would have uncertain loyalties. With a few minor exceptions, from the Founding until the middle of the twentieth century, the child of an American father born outside the country was not a citizen at birth, but could later became an American citizen under rules laid out by Congress.
The Fourteenth Amendment, ratified in 1868, provides that "All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States." This language is unambiguous. There are only two ways to be a citizen: birth in the United States or naturalization. Today children of US citizens born outside the United States are effectively "naturalized" by statutes giving them citizenship at birth. Without such laws, which have not always been on the books, they would not be citizens.
This leads to Ted Cruz, who was born in Canada in 1970. Under Canadian law (and US law as well) Cruz was a Canadian citizen at birth. This is not disputed. Indeed, he remained a Canadian citizen until 2014 -- more than a year after he was elected to the U.S. Senate. Cruz's mother was born in the United States and, assuming she was still a US citizen, under existing federal law at the time of his birth Cruz was entitled to American citizenship. His father was a native of Cuba, but his nationality at the time of Cruz's birth is unclear. He may still have been a Cuban citizen or a Canadian citizen or both. (If Cruz's father was a citizen of Cuba in 1970 then, under Cuban law, Cruz may also be a citizen of that country.) The Cruz campaign claims that neither of his parents were ever Canadian citizens, although in 1974 his parents were listed as voters in Canada.
Whatever the status of his parents, under the original Constitution and the Fourteenth Amendment Cruz is not a natural born citizen of the United States. As the Fourteenth Amendment notes, there are only two kinds of citizens -- those born "in the United States" and those who are naturalized. Cruz was not born in the United States. However, as the child of an American citizen born outside the United States, he was effectively naturalized at birth through various acts of Congress.
Because Senator Cruz was not born in the United States he does not appear to be constitutionally qualified to be president. Cruz's own behavior underscores the Founders' fear of someone with a foreign allegiance becoming President and Commander-in-Chief. In 2014, at the age of 44, almost two years after he was elected to the US Senate from Texas, Cruz renounced his Canadian citizenship. (He has never dealt with his possible Cuban citizenship.) Cruz has never sufficiently explained why he remained a Canadian citizen for two decades after reaching the age of maturity. Perhaps he contemplated leaving the US for England, Canada, or some other part of the British Commonwealth, or even pursuing a Canadian political career before he became a US Senator from Texas? The Framers adopted the Natural Born Citizenship Clause precisely to avoid this sort of uncertainty and these sorts of dual loyalties.
Cruz embodies the purpose of the natural born citizen clause. He was a subject of the English crown for 44 of his 46 years. George Washington, who risked his life, fortune, and sacred honor in a war against the English monarchy, would be shocked that a lifelong subject of that monarchy could be president.
This issue is not new. Franklin D. Roosevelt, Jr. declined to be considered for the presidency because his parents, both US citizens, were vacationing in Canada when he was born. In 1968 some people challenged George Romney's presidential ambitions because he had been born in Mexico, where his American parents were living. Romney was not automatically a citizen under US law at the time of his birth, but his campaign fizzled before the issue could be resolved. John McCain was born in 1936 in Panama, where his father, Admiral McCain, was stationed. A year after McCain's birth Congress passed legislation retroactively giving citizenship to children of US personnel born in the Canal Zone. The fact that Congress passed such a law demonstrates that at the time of his birth McCain was not a citizen. In 2008 the Senate unanimously passed a nonbinding resolution declaring McCain a "natural born citizen," despite the fact that at the time of his birth US law held the opposite. Because McCain lost the election this issue remained unresolved.
The case for Senator Cruz is weaker than McCain's or Franklin Roosevelt Jr's. He was born in a foreign country, not a US dependency (like Panama) and was a Canadian citizen at birth, by virtue of Canadian law and the apparent citizenship of both his parents. He remained a Canadian citizen until 2014. Only his mother was American. His parents were not outside the US on behalf of the government (as McCain's had been) or on vacation (as FDR Jr.'s were), but were working for a private company and were in Canada, possibly as citizens of that country, for an undetermined length of time.
Senator Cruz would not be the first politician to find that the natural born citizenship clause has thwarted his personal ambitions. Governors Arnold Schwarzenegger and Jennifer Granholm and cabinet secretaries Henry Kissinger, Madeleine Albright, and Michael Blumenthal were all barred from aspiring to the presidency. Despite complaints about the clause, whether through inertia or respect for the wisdom of the Founders, Congress has never seriously considered an amendment to change it.
Senator Cruz argues that "natural born" must include the children of American citizens born abroad, but this was not true in 1789. Even today not all children of US citizens born outside the country are citizens at birth. Congress has the power to regulate naturalization and under current law Congress provides that all children of US citizens who are born abroad are citizens. But this does not make them "natural born citizen." Rather, under the Fourteenth Amendment it makes them naturalized by an act of Congress. Cruz was a US citizen at birth only because of a statute, which in effect grants naturalization to the foreign-born children of US citizens. At various times Congress has required such children to register for their citizenship, return to the United States within a specified period of time, or take some other affirmative actions to secure their citizenship. Congress could change these laws at any time, and has changed them many times. Thus, Cruz is a "naturalized" citizen only because of a statute passed by Congress and signed by the president. Without this statute he would not have been a US citizen at birth. But it is clear, from the entire history of the nation that being a citizen because of an act of Congress is not the same as being a "natural born citizen."
In 1787 when the Constitution was written and in 1868 when the Fourteenth Amendment was ratified, "natural born" was always been interpreted as born within the United States. Thus the Supreme Court said in United States v. Wong Kim Ark (1898): "A person born out of the jurisdiction of the United States can only become a citizen by being naturalized, either by treaty ... or by authority of Congress ... conferring citizenship upon foreign-born children of citizens..." That describes Senator Cruz. Until the Supreme Court reverses its precedents on these matters, or we amendment Constitution, Senator Cruz seems to lack the constitutional requirements to be president.