A natural-born citizen is someone who is automatically a citizen at birth by virtue of nature, rather than by statute or through the process of naturalization. The U.S. Constitution requires that the U.S. president be a natural-born citizen. Donald Trump has threatened to sue Ted Cruz over this issue, and others have already done so.
There are about 20 million naturalized citizens in the United States who are not "natural-born citizens." Naturalized citizens are subject to denaturalization and deportation, which natural-born citizens are not.
Meaning of the term
Natural-born citizen evidently comes from the writings of Emmerich de Vatell (1714-1767), a Swiss philosopher and legal scholar who laid the foundations and concepts of modern law.
"The citizens are the members of the civil society; bound to this society by certain duties, and subject to its authority, they equally participate in its advantages. The natives, or natural-born citizens, are those born in the country, of parents who are citizens. As the society cannot exist and perpetuate itself otherwise than by the children of the citizens, those children naturally follow the condition of their fathers, and succeed to all their rights. The society is supposed to desire this, in consequence of what it owes to its own preservation; and it is presumed, as matter of course, that each citizen, on entering into society, reserves to his children the right of becoming members of it. The country of the fathers is therefore that of the children; and these become true citizens merely by their tacit consent. We shall soon see whether, on their coming to the years of discretion, they may renounce their right, and what they owe to the society in which they were born. I say, that, in order to be of the country, it is necessary that a person be born of a father who is a citizen; for, if he is born there of a foreigner, it will be only the place of his birth, and not his country."
Thomas Jefferson gave a further definition prior to the drafting of the United States Constitution: "A Natural subject is one born within the king's allegiance & still owing allegiance. No instance can be produced in the English law, nor can it admit the idea of a person's being a natural subject and yet not owing allegiance. An alien is the subject or citizen of a foreign power." John Jay, in a letter to George Washington while he served as president of the Constitutional Convention, went further with a pointed question: "Permit me to hint whether it would not be wise and seasonable to provide a strong check to the admission of foreigners into the administration of our national government; and to declare expressly that the command in chief of the American army shall not be given to, nor devolve on any but a natural born citizen." The implication is that the President of the United States should have loyalty to no country other than his own, which is naturally-guaranteed by birth to two citizen parents.
Jay apparently had some influence on Washington, for when the Convention ended and the new Constitution was ratified, only the qualifications for the office of president in Article II had the term "natural-born"; the qualifications for Senator and Representative in Article I did not: "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...."
Because the Constitution fails to define the term "natural born Citizen", establishment of its precise meaning would fall to Congress or the courts. The only US law that has ever employed the exact term "natural born citizen" is the Naturalization Act of 1790:
And the children of citizens of the United States, that may be born beyond sea, or out of the limits of the United States, shall be considered natural born citizens: Provided, That the right of citizenship shall not descend to persons whose fathers have never been resident in the United States: Provided also, That no person heretofore proscribed by any state, shall be admitted a citizen as aforesaid, except by an act of the legislature of the state in which such person was proscribed.
This law was passed by the First Congress, which counted among its members nearly half of the signers of the Constitution (and was signed into law by a president who was also a signer of the Constitution), so it may give some insight into the intention behind this provision. However, the 1790 act was repealed in 1795, and no subsequent law or court decision has clearly defined “natural born Citizen”.
Therefore, there is still discussion over exactly who meets the definition of a natural-born citizen. It is clear that someone who was not a citizen from birth, but acquired citizenship through naturalization, is not one. One view is that all others, meaning anyone who is a citizen from the moment of birth, are natural-born citizens. There are arguments that a third category exists, of those who are citizens from birth by law or status, but are not intended to be considered as natural born. The most common reasons given are that the birth did not take place within the US, or that one of the birth parents was not a US citizen.
Presidential candidate John McCain was born to U.S. military parents stationed in the Panama Canal Zone, a territory within Panama which until 1978 was administered by the United States. The Senate passed a nonbinding resolution declaring that he was indeed a natural born citizen.
U.S. Supreme Court cases that cite natural born citizenship when both parents are citizens, and birthplace is on U.S. soil.
- The Venus, 12 U.S. 8 Cranch 253 253 (1814)
Vattel, who, though not very full to this point, is more explicit and more satisfactory on it than any other whose work has fallen into my hands, says: “The citizens are the members of the civil society; bound to this society by certain duties, and subject to its authority, they equally participate in its advantages. The natives or indigenes are those born in the country of parents who are citizens. Society not being able to subsist and to perpetuate itself but by the children of the citizens, those children naturally follow the condition of their fathers, and succeed to all their rights.
- Shanks v. Dupont, 28 U.S. 3 Pet. 242 242 (1830)
Ann Scott was born in South Carolina before the American revolution, and her father adhered to the American cause and remained and was at his death a citizen of South Carolina. There is no dispute that his daughter Ann, at the time of the Revolution and afterwards, remained in South Carolina until December, 1782. Whether she was of age during this time does not appear. If she was, then her birth and residence might be deemed to constitute her by election a citizen of South Carolina. If she was not of age, then she might well be deemed under the circumstances of this case to hold the citizenship of her father, for children born in a country, continuing while under age in the family of the father, partake of his national character as a citizen of that country. Her citizenship, then, being prima facie established, and indeed this is admitted in the pleadings, has it ever been lost, or was it lost before the death of her father, so that the estate in question was, upon the descent cast, incapable of vesting in her? Upon the facts stated, it appears to us that it was not lost and that she was capable of taking it at the time of the descent cast.
- Dred Scott v. Sandford, 60 U.S. 393 (1857)
The citizens are the members of the civil society; bound to this society by certain duties, and subject to its authority, they equally participate in its advantages. The natives, or natural-born citizens, are those born in the country, of parents who are citizens. As society cannot perpetuate itself otherwise than by the children of the citizens, those children naturally follow the condition of their parents, and succeed to all their rights.' Again: 'I say, to be of the country, it is necessary to be born of a person who is a citizen; for if he be born there of a foreigner, it will be only the place of his birth, and not his country. . . .
- Minor v. Happersett, 88 U.S. 162 (1875)
The Constitution does not in words say who shall be natural-born citizens. Resort must be had elsewhere to ascertain that. At common law, with the nomenclature of which the framers of the Constitution were familiar, it was never doubted that all children born in a country of parents who were its citizens became themselves, upon their birth, citizens also. These were natives or natural-born citizens, as distinguished from aliens or foreigners. Some authorities go further and include as citizens children born within the jurisdiction without reference to the citizenship of their parents. As to this class there have been doubts, but never as to the first.
- United States v. Wong Kim Ark, 169 U.S. 649 (1898)
At common law, with the nomenclature of which the framers of the Constitution were familiar, it was never doubted that all children, born in a country of parents who were its citizens, became themselves, upon their birth, citizens also. These were natives, or natural-born citizens, as distinguished from aliens or foreigners.
- Perkins v. Elg, 307 U.S. 325 (1939),
was a decision by the Supreme Court of the United States that a child born in the United States to naturalized parents on U.S. soil is a natural born citizen and that the child's natural born citizenship is not lost if the child is taken to and raised in the country of the parents' origin, provided that upon attaining the age of majority, the child elects to retain U.S. citizenship "and to return to the United States to assume its duties." Not only did the court rule that she did not lose her native born Citizenship but it upheld the lower courts decision that she is a "natural born Citizen of the United States" because she was born in the USA to two naturalized U.S. Citizens.
Ann Coulter's analysis
Ann Coulter analyzed "natural born Citizen" as follows:
- A child born to American parents outside of U.S. territory may be a citizen the moment he is born – but only by “naturalization,” i.e., by laws passed by Congress. If Congress has to write a law to make you a citizen, you’re not “natural born.”
Two presidents were born having a father who was not a citizen.
- Chester Arthur was born in the US (though rumored to have been born in Canada), but his father was at that time a citizen of the UK.
- Barack Obama, who was reportedly born in Hawaii on August 4, 1961. His father was a British national from Kenya who was at that time attended a university on a student visa.
Three potential candidates for the Presidential Election 2016 were born having a parent who was not a citizen.
- Marco Rubio was born in the US, but his parents were Cuban exiles who were not US citizens at the time.
- Bobby Jindal was born in the US, but his parents were Indian nationals at the time of his birth.
- Ted Cruz was born in Canada, his father was Cuban national at the time of his birth.
A number of past Presidential candidates also raised controversy:
- George Romney, Governor of Michigan, ran in the 1968 Republican Presidential primaries even though he was born in Mexico with both of his parents being US citizens.
- John McCain ran for President as the Republican nominee in 2008, even though he was born in the Panama Canal Zone. However, he is a natural-born citizen as defined by the Naturalization Act of 1790.
- Rogers v. Bellei (1971) - a U.S. Supreme Court ruling that a person born outside of the U.S. to one parent who is an American citizen, and one who is not, obtains citizenship only if a residency requirement is fulfilled.
- Birthright Citizenship
- de Vatell, Emmerich. The Law of Nations; T. & J.W. Johnson & Company, Philadelphia (1883)
- Personal blog which goes into detail on an 1896 case
- Sen. Ted Cruz's birth certificate shows he was born in Canada in 1970. It was released exclusively to The Dallas Morning News. 
- Vatell: CHAP. XIX. OF OUR NATIVE COUNTRY, AND SEVERAL THINGS THAT RELATE TO IT.
- Notes by Jefferson, December, 1783, pertaining to letters written by Delegates to Congress
- S.Res.511: A resolution recognizing that John Sidney McCain III, is a natural born citizen; sponsors: Sen. Claire McCaskill, Sen. Barack Obama et al.
- "Romney's birth certificate evokes his father's controversy", May 29, 2012. Retrieved on August 11, 2012.
- Hulse, Carl. "McCain’s Canal Zone Birth Prompts Queries About Whether That Rules Him Out", The New York Times, February 28, 2008. Retrieved on August 11, 2014.