While coming tantalizingly close, no US Court has ever decided the definition of “natural born citizen.” The term was not explained in the debates of the Constitutional Convention, nor the state legislatures when it was ratified, nor by individual framers in their speeches, letters or papers. Where do we go for a definition–to an 18th century Swiss philosopher–to an appeal to our shared prejudices?
The US Constitution is replete with terms that it doesn’t define: citizen, impeachment, felonies, treason, bribery, bankruptcy, warrants, grand jury and attainder. These are, however, familiar terms in the common law. The Supreme Court wrote in the case of Smith v. Alabama (1888) 124 U.S. 465:
There is no common law of the United States, in the sense of a national customary law, distinct from the common law of England as adopted by the several States each for itself, applied as its local law, and subject to such alteration as may be provided by its own statutes. . . . There is, however, one clear exception to the statement that there is no national common law. The interpretation of the Constitution of the United States is necessarily influenced by the fact that its provisions are framed in the language of the English common law, and are to be read in the light of its history.
It is clear from the language of colonial laws, from inheritance law in South Carolina in 1711 and the Georgia Charter of 1732 to the naturalization acts of New York and Massachusetts in 1770-1776, that the colonial legislatures followed the principle of English common law, that all persons born in the colony were natural born subjects.
The state of English common law may be succinctly summed up by this comment from Lord Chief Justice Cockburn, as cited by the United States Supreme Court in United States v. Wong Kim Ark:
By the common law of England, every person born within the dominions of the Crown, no matter whether of English or of foreign parents, and, in the latter case, whether the parents were settled or merely temporarily sojourning, in the country, was an English subject, save only the children of foreign ambassadors (who were excepted because their fathers carried their own nationality with them), or a child born to a foreigner during the hostile occupation of any part of the territories of England. No effect appears to have been given to descent as a source of nationality.
When looking at some comments in the legislative debates over citizenship, we see words like “allegiance” and “sovereignty.” What must be understood is that a nation exercises absolute sovereignty within its borders. Chief Justice Marshall in the case of The Exchange (1812) said:
The jurisdiction of the nation within its own territory is necessarily exclusive and absolute. It is susceptible of no limitation not imposed by itself. Any restriction upon it, deriving validity from an external source, would imply a diminution of its sovereignty to the extent of the restriction, and an investment of that sovereignty to the same extent in that power which could impose such restriction. All exceptions, therefore, to the full and complete power of a nation within its own territories must be traced up to the consent of the nation itself. They can flow from no other legitimate source. This consent may be either express or implied. In the latter case, it is less determinate, exposed more to the uncertainties of construction; but, if understood, not less obligatory.
(This principle is not honored by anyone who says that the British Nationality Act of 1948 controls who may and who may not be president of the United States.)
Because the internal sovereignty of the United States is absolute, those aliens visiting here are also absolutely under the sovereignty of the United States. This and many other similar principles, dicta and precedent lead Chief Justice Gray, in Wong, to conclude:
Every citizen or subject of another country, while domiciled here, is within the allegiance and the protection, and consequently subject to the jurisdiction, of the United States. His allegiance to the United States is direct and immediate, and, although but local and temporary, continuing only so long as he remains within our territory, is yet, in the words of Lord Coke in Calvin’s Case, 7 Rep. 6a, “strong enough to make a natural subject, for if he hath issue here, that issue is a natural-born subject;” [emphasis added]
And there, in most abbreviated form, is the argument that leads inevitably to the conclusion that all those born within one of the United States of America except those whom our country grants exemption from our jurisdiction (such as foreign ambassadors), are natural born citizens of the United States.
For a more lengthy set of citations, see The Great Mother of All Natural Born Citizen Quotation Pages and Natural Born Citizen: Defined!