This is not a definition of allegiance to the sovereign within one’s jurisdiction that depends on having been legally admitted to the country. Which is not surprising: while the right to exclude aliens from the jurisdiction is an ancient attribute of sovereignty, most of human history has not been characterized by airtight borders, enforced by vetting and documentation of new entrants. Laws have always assumed that anyone found in the land should be subject to the authority of the sovereign, regardless of how they got there. That rule applied unless there was some good reason – diplomatic immunity, being a lawful foreign combatant, being a member of a separately sovereign internal group like Native American tribes – to be outside the ordinary reach of the law. This is the legal backdrop that led Edward Bates, President Lincoln’s Attorney General, to write just a few years before the adoption of the Fourteenth Amendment:

“I am quite clear in the opinion that children born in the United States of alien parents, who have never been naturalized, are native-born citizens of the United States, and, of course, do not require the formality of naturalization to entitle them to the rights and privileges of such citizenship.”

The Fourteenth Amendment, which incorporated Senator Howard’s language, is properly understood to have codified Attorney General Bates’ contemporary understanding. That is what it meant when it was adopted in 1868, and no amount of current political controversy about illegal immigration should lead conservative critics of birthright citizenship to abandon that original understanding.