Birthright citizenship is the latest issue to arise in immigration politics, with a handful of very influential Republicans calling either for its end, or for hearings to examine what its end would look like.
But there are serious questions as to how birthright citizenship can be addressed. As noted previously, there are two camps on the issue: those who think it can be changed via statute, i.e. a bill passed by Congress, and those who think it requires a constitutional amendment, meaning passage by two-thirds of Congress and ratification by three-fourths of the states.
With discussion by Sens. Lindsey Graham and Jon Kyl, in addition to Senate Minority Leader Mitch McConnell, and a Republican-sponsored bill carrying 93 cosponsors that's been floating around the House for years, an end to birthright citizenship has its notable supporters (and its ardent opponents) and has worked its way into the discussion of GOP immigration policies.
The policy rests on the first sentence of the Constitution's 14th Amendment, which states: "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 legal question, at its most basic, is this: does that clause ensure citizenship for the children of illegal immigrants?
The answer is complicated. So complicated, in fact, that there is no definitive answer, and the Supreme Court has never ruled on the matter directly.
It turns on this phrase: "subject to the jurisdiction thereof." There is a serious question as to whether or not the children of illegal aliens are "subject to the jurisdiction" of the United States; since the amendment does not define "jurisdiction," scholarly debate has ensued over what "jurisdiction" does, can, and should mean.
The Supreme Court has never ruled on the issue. In the 1982 case Plyler v. Doe, the court interpreted "jurisdiction" geographically--opining that illegals are subject to "jurisdiction" simply by being within the borders of a state--but that interpretation came in a dictum, a finding related, but not essential, to the decision. In the 1898 case United States v. Wong Kim Ark, the court ruled that the child of legal permanent residents (in this case from China) is a rightful citizen. But that's the closest the court has gotten, and it doesn't answer the question for children of illegal immigrants.
"It does not speak to the question which is now roiling the Congress," Yale Law Professor Peter Schuck, one of the leading experts on birthright citizenship's constitutionality, told me.
"The Supreme Court has never squarely confronted the issue," Schuck said, although it "seems to have assumed without deciding that they are citizens, but they have never faced it."
Beyond the "jurisdiction" question, there is the historical context of the 14th Amendment itself.
Congressman Lamar Smith, the ranking member of the House Judiciary Committee and a leading proponent of ending birthright citizenship via a bill in Congress, has noted that the 14th Amendment was drafted after the Civil War and that its citizenship clause was intended to grant citizenship to freed slaves. Smith quotes one of the authors of the amendment, Sen. Jacob Meritt Howard, as saying that the citizenship clause would "not of course include persons born in the United States who are foreigners."
If the language of a particular law is unclear, courts turn to analysis of the law's intent. But how to analyze legislative intent is a question of judicial philosophy on which legal experts and Supreme Court justices differ.
Conservative jurists, in their tendency toward strict interpretation, prefer to stick closer to the language of the law itself. Liberal jurists are more open to including, for instance, historical context and public statements made around the passage of a law. So liberal immigration voices, who hold that the 14th Amendment does grant citizenship to all children of illegals, may find a more natural alliance with the Supreme Court's most conservative members. Justice Antonin Scalia, for instance, may be less open to hearing about a quote from Sen. Howard than Justice Anthony Kennedy.
But without a clear precedent, and with the language up for serious debate from both sides, it seems clear that the Supreme Court will have to decide the matter, if it goes that far.
With no clear political consensus to end birthright citizenship, a constitutional amendment would be nearly impossibly to pass. Republican takeovers of the House and Senate, and passage of a new citizenship law, is a much more likely (if still unlikely) scenario. And in that case, the bill would likely be appealed, possibly reaching the Supreme Court.
Facing that reality, Republicans probably won't try to pass a bill, even in the years of decades to come, with the intent of ending birthright citizenship immediately; rather, any serious legislative effort will be about (aside from making a point about the GOP's stance on the issue) initiating a process in which the Supreme Court plays the final arbiter.
Chris Good is a political reporter for ABC News. He was previously an associate editor at The Atlantic and a reporter for The Hill.