While the original Constitution required “citizenship” for federal office, it did not define the term until 1868, when the 14th Amendment was ratified. That amendment’s Citizenship Clause provides: “All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.” The provision effectively constitutionalized the British common-law rule of jus soli, under which, as 18th-century English jurist William Blackstone explained, “the children of aliens, born here in England, are, generally speaking, natural-born subjects, and entitled to all the privileges of such.”
The common-law rule of jus soli derives from a 1608 English decision known as Calvin’s Case, which arose when King James VI of Scotland ascended to the throne of England as King James I. This union between England and Scotland through a single monarch was purely personal and dynastic; it did not represent the legal or political integration of the two kingdoms, which remained distinct until they were united by the Acts of Union in 1707. Calvin’s Case asked whether persons born in Scotland under King James VI — his subjects in Scotland — were to be considered aliens in England or subjects of King James I.
The lead opinion in the case, which was widely accessible to American lawyers of the founding, was Edward Coke’s. As Coke explained:
Every one born within the dominions of the King of England, whether here or in his colonies or dependencies, being under the protection of — therefore, according to our common law, owes allegiance to — the King and is subject to all the duties and entitled to enjoy all the rights and liberties of an Englishman.
One became a natural-born English subject, therefore, upon being born within any of the king’s dominions. The birth of a subject created a reciprocal relationship between the subject and the king whereby the subject had a right to the king’s protection while the king had a right to the subject’s allegiance. Calvin’s Case embodies this doctrine, known today as jus soli.
American courts’ and commentators’ embrace of jus soli traces back to the early days of the republic. Gardner v. Ward, for instance, was an 1806 Massachusetts case involving a merchant born in the American colonies before the Revolution. Local officials contended that the merchant’s absence from his birthplace and residence in the British colonies for part of the Revolutionary War’s duration meant that he was an alien who could not vote in a local election. The court disagreed, deciding instead in the merchant’s favor:
I take it then to be established, with a few exceptions not requiring our present notice, that a man, born within the jurisdiction of the common law, is a citizen of the country wherein he is born. By this circumstance of his birth, he is subjected to the duty of allegiance, which is claimed and enforced by the sovereign of his native land; and becomes reciprocally entitled to the protection of that sovereign and to the other rights and advantages, which are included in the term citizenship. The place of birth is coextensive with the dominions of the sovereignty, entitled to the duty of allegiance.
Justice Joseph Story’s dissent in the 1830 case Inglis v. Trustees of Sailor’s Snug Harbor further elucidated jus soli. Story wrote that two conditions “usually concur to create citizenship — first, birth locally within the dominions of the sovereign, and secondly birth within the protection and obedience, or in other words within the ligeance of the sovereign.” Both conditions are met when the child is “born within a place where the sovereign is at the time in full possession and exercise of his power” and when the child “at his birth derive[s] protection from, and consequently owe[s] obedience or allegiance to the sovereign as such, de facto.” Again, the parents’ legal status had no bearing on the citizenship of a baby born on American territory.
Even shortly before the 14th Amendment was ratified, American judges affirmed the jus soli doctrine.
