Article II Sec. 1 of the Constitution lays out requirements for the presidency, including a stipulation that “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.”

We find little debate about the reason for this requirement, but the exact definition of “natural born citizen” remains muddy because we have no definitive, authoritative source to appeal to.

The citizenship requirement was meant to eliminate the possibility of a president maintaining loyalty to some other country. St. George Tucker authored the first comprehensive commentary on the U.S. Constitution and explained the reason for the citizenship clause.

That provision in the constitution which requires that the president shall be a native-born citizen (unless he were a citizen of the United States when the constitution was adopted,) is a happy means of security against foreign influence, which, wherever it is capable of being exerted, is to be dreaded more than the plague. The admission of foreigners into our councils, consequently, cannot be too much guarded against; their total exclusion from a station to which foreign nations have been accustomed to, attach ideas of sovereign power, sacredness of character, and hereditary right, is a measure of the most consummate policy and wisdom.

But what exactly did “natural born citizen” mean in the founding era?

In his book, The Original Constitution, scholar Rob Natelson argues that the term was adapted from the English legal term “natural born subject”as defined by Blackstone. He points out that natural born subject was the criteria defining who could serve in Parliament or the Privy Council. At the time the Constitution was ratified, a natural born subject was either a person “born within the dominions of the crown of England,” or those born outside of British territory to a father who was a subject. Translated to the American system, this would make any person born within the United States, even to alien parents, or those born outside of the United States to an American father, natural born citizens.

Swiss common law scholar Emer de Vattel argued that citizenship followed the parents, not the place of birth. That would mean those born within the borders of the United States to alien parents would not count as natural born citizens. But considering the fact that Americans generally adopted English legal principles as their own, and that the legal framework of the Constitution was based on an English law foundation, Natleson’s view seems to stand on solid ground.

But it does raise some issues, namely that the original English view of natural born citizen only included those born within the British Empire, with a common law exception for those whose parents served overseas as ambassadors. As scholar Mike Ramsey points out, the citizenship provisions established later for those born outside the Empire’s borders to English parents was dictated by parliamentary statute.

But as Blackstone further describes, the rights of natural born subjects were extended by statute early on (under Edward III) to those born abroad of two English parents.  Then, in the early eighteenth century, parliament made birth subjects of children born abroad with an English father.  According to Blackstone, as a result these children “are now natural-born subjects themselves, to all intents and purposes, without exception.

The term “natural” would seem to indicate that only those born within the borders of the British Empire were technically natural born subjects, as the later expansion of British citizenship was statutory – generally understood as the opposite of natural.

So, was the American understanding of natural born citizen based on the earliest English principle, only including those born within the United States, or did it include the broader 18th century definition as Natelson argues?

That remains unclear.

But a key piece of evidence seems to indicate the broader understanding was intended. In 1790, the First Congress provided for citizenship rights to children born outside of the U.S. to two American parents.

Children of citizens of the United States, that may be born beyond sea, or out of limits of the United States, shall be considered as citizens of the United States.

This would seem to indicate that the original understanding of “natural born citizen” followed the meaning of “natural born subject” at the time of ratification, as Natelson asserts.

Ramsey sums up this view.

When the American founders thought of the “traditional” English rule, they actually thought of the eighteenth-century rule as stated in Blackstone, their chief legal authority.  Hence “natural born” in 1788-89 America meant what it then meant in England: born in the territory, or born abroad to an English father.  That explains the 1790 Act.

If we accept this view, it raises still another question: is “natural born citizen” generally subject to statutory definition? In other words, can Congress define the term as it chooses?

As Ramsey explains, Parliament arguably set this precedent.

That appears to be the power parliament claimed in making natural born subjects of children born abroad with English fathers.  According to Blackstone, at least, the statute did not just give them the rights of natural born subjects; rather he said that by statute children born abroad “are” natural born subjects.  In this view, parliament could have made natural born subjects of the children of English mothers.  It chose not to – perhaps because the Roman/continental rule made citizenship follow the father’s status; perhaps because there simply weren’t very many English women (as opposed to men) living or traveling abroad and having children with foreigners.  But in any event “natural born” had come to mean those children parliament made subjects at birth, whoever they were.  Translated to U.S. constitutional terms, that would mean whomever Congress chooses (from time to time) to make citizens at birth are natural born.

Although this view makes sense on the surface, we cannot equate Parliament with Congress. Parliament was essentially a sovereign institution in the British system. It was not bound by the English constitution. In fact, in the British system, every act of Parliament was, in essence, part of the constitution. In contrast, the U.S. Constitution limits congressional authority to specific objects. There exists no enumerated power authorizing Congress to redefine “natural born citizen” by statute. That definition was fixed at the ratification of the Constitution.

Constitutional scholar Randy Barnett adds another layer of texture to the debate. He takes a completely different approach and argues that in order to understand the term “natural born citizen,” one must consider sovereignty. In the British system, the king was sovereign, but in American political thought, the individual stands as the sovereign.

An individual conception of sovereignty would also affect who is a natural born citizen. In England, one would be a natural born subject of the King if born on English soil over which the King has jurisdiction.  But, as Sandy Levinson notes: “a child born to British monarchs while travelling abroad . . . would be eligible to become king or queen.”  In other words, because the King is the sovereign, his offspring are his natural born subjects as his children who owe him a natural duty of obedience, just as do those who are born within his territorial jurisdiction.

By contrast, in the United States, if each individual citizen is sovereign, so too are their offspring “natural born citizens.” Because the term “natural born citizen” was invented for use in the Constitution, its public meaning was dictated by theoretical considerations such as these, rather than either by English legal thought or by widespread public usage.  This individualist understanding of natural born citizen simply adapts the English usage to American political theory by recognizing the difference in who is the sovereign in each system.

If this is correct, then the term “natural” in “natural born citizen” is not surplusage, and, in the 1790 Naturalization Act, Congress might well have merely been codifying the underlying popular sovereignty conception of natural born citizen as children born to sovereign American citizens.

In my view, Barnett’s argument carries the most weight. It reconciles the original English meaning of natural born subject with American thought. And practically speaking, we essentially end up in pretty close agreement with Natelson, except under Barnett’s understanding, a child born outside of the U.S. would need both parents to count as citizens, not just the father.