Just how seriously should we take Donald Trump’s pledge — seven days before a critical midterm election — to issue an executive order undoing “birthright” citizenship? Probably not very seriously or literally; it’s a signaling exercise, or at the most a poke at Congress to move back towards his position on the wall. Even if Trump did issue such an EO, there wouldn’t be much that it would authorize except the deportation of people born in the US, and the Trump administration can’t even execute deportations of all the people who weren’t born in the US that are in the pipeline now.

Let’s say that Trump did sign the EO and it teed up a court fight that could clear the ripeness threshold. The case would rest on the language of the 14th Amendment, section 1:

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. No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.

The language in question here is “and subject to the jurisdiction thereof.” There are  a few different ways to read this. One interpretation would be that the clause referred to non-sovereign territories under the jurisdiction of the United States at the time. When this amendment was drafted and ratified in 1868, the Confederate states had been temporarily deprived of their sovereignty during Reconstruction, which lasted until the election of 1876. The US at that time also had significant territories that had not yet achieved statehood, including what is now the states of Washington, Montana, Idaho, the Dakotas, Wyoming, Utah, Arizona, New Mexico, and the newly purchased Alaska. That clause extended birthright citizenship to all born those territories outside of a “State in which they reside.” Otherwise, all those born in those territories would have required naturalization, which we know historically wasn’t demanded or needed.

There are other interpretations too, including that of advocates that see the “and” as an exclusionary device rather than inclusionary. In this interpretation, one had to be both born in the United States and subject to its jurisdiction to be a citizen. To apply that to modern times, those who come in illegally would not be “subject to the jurisdiction” of the US. That, however, isn’t true in both practical and legal terms. Everyone in the US is subject to its laws and prosecutable for crimes within it, except for those with diplomatic immunity as subject to another jurisdiction. Illegal aliens can be deported for those crimes or they can serve long prison sentences here precisely because they are subject to our jurisdiction, while the children of diplomats born here are not citizens because they aren’t subject to it.

It all makes for an interesting legal argument, but it’s been largely settled by the US Supreme Court in 1898 with US v Wong Kim Ark. Jurisdiction was the topic of extensive discussion in the majority opinion, with well over 100 mentions in the text besides citations of the 14th Amendment. It cites 300 years of English common-law precedent in birthright citizenship as the background to interpreting the 14th Amendment:

It thus clearly appears that, by the law of England for the last three centuries, beginning before the settlement of this country and continuing to the present day, aliens, while residing in the dominions possessed by the Crown of England, were within the allegiance, the obedience, the faith or loyalty, the protection, the power, the jurisdiction of the English Sovereign, and therefore every child born in England of alien parents was a natural-born subject unless the child of an ambassador or other diplomatic agent of a foreign State or of an alien enemy in hostile occupation of the place where the child was born.

The court then cited a number of cases in the states which upheld this principle of jurisdiction, citing James Kent’s Commentaries on American Law (published in 1826), emphasis mine:

Natives are all persons born within the jurisdiction and allegiance of the United States. This is the rule of the common law, without any regard or reference to the political condition or allegiance of their parents, with the exception of the children of ambassadors, who are in theory born within the allegiance of the foreign power they represent.

In other words, the defects of the parents do not alter or abrogate the citizenship of a child born in the jurisdiction of the US. The Supreme Court’s inclusion of this in their opinion goes directly to the question and stands in opposition to the exclusionary reading of the clause. In a later citation of Kent, he explains what “jurisdiction” means in this instance:

And if, at common law, all human beings born within the ligeance of the King, and under the King’s obedience, were natural-born subjects, and not aliens, I do not perceive why this doctrine does not apply to these United States, in all cases in which there is no express constitutional or statute declaration to the contrary. . . . Subject and citizen are, in a degree, convertible terms as applied to natives, and though the term citizen seems to be appropriate to republican freemen, yet we are, equally with the inhabitants of all other countries, subjects, for we are equally bound by allegiance and subjection to the government and law of the land.

A later citation of Binney makes it even more explicit:

The right of citizenship never descends in the legal sense, either by the common law or under the common naturalization acts. It is incident to birth in the country, or it is given personally by statute. The child of an alien, if born in the country, is as much a citizen as the natural born child of a citizen, and by operation of the same principle.

So while it is true that Wong Kim Ark considered a case where the parents migrated legally, the issue of jurisdiction did not and does not rely on that point.

Does that settle the matter? Well, who knows? The Supreme Court could decide to take up the question again; they are guided by precedent but not forever bound by it. It’s not as simple as overturning Wong Kim Ark, though; as the opinion amply demonstrates, it would take overturning several decades of precedent before the decision and more than a century of unremarkable precedent after it, too. But just as some hope for an overturning of Roe v Wade and Wickard v Filburn, it’s not impossible either. Just … highly unlikely.

I suspect that Trump’s just posturing here, and that the promised EO never materializes. If it does, though, Trump’s got his work cut out for him. He’d better have top men working on the legal fight right now — Top. Men. That prompts a question, though: if this is such a popular point of view, why not just amend the Constitution to more clearly define the grant of citizenship?

Updated: The Washington Post’s Robert Barnes also notes that the Supreme Court referenced Wong Kim Ark in 1982’s Plyler v Doe, affirming that the immigration status of the parents was irrelevant:

Related, but less directly on point, was the 1982 case Plyler v. Doe, which held that denying illegal immigrant children admission to public schools would violate the 14th Amendment’s equal protection clause.

Justice William Brennan, writing for the majority in the 5-to-4 decision, noted language from the Wong Kim Ark decision.

He said that “no plausible distinction with respect to Fourteenth Amendment ‘jurisdiction’ can be drawn between resident aliens whose entry into the United States was lawful, and resident aliens whose entry was unlawful.”

Again, the Supreme Court has plenary authority to overturn its own decisions, but there is a thicket of precedent that extends four centuries into English common law. Those are not usually the kinds of decisions that get overturned.