The U.S. Supreme Court on Monday heard arguments in what could be one of the most important immigrant rights cases in decades, Sessions v. Dimaya. 

The case was carried over from the last term, when the justices were deadlocked 4 to 4 on the question of whether the general definition of a “crime of violence” for purposes of federal immigration law is unconstitutionally vague.

Under current immigration law, a noncitizen—even one who is a lawful permanent resident—convicted of an “aggravated felony” is subject to mandatory removal. The Immigration and Nationality Act defines “aggravated felonies” expansively to include “any … offense that is a felony and that, by its nature, involves a substantial risk that physical force against the person or property of another may be used in the course of committing the offense.”

The plaintiff in the case, James Garcia Dimaya, immigrated lawfully from the Philippines to the United States in 1992. While in the United States, Dimaya was convicted twice for residential burglary, though neither conviction involved an act of violence. Nevertheless, the immigration court and the Board of Immigration Appeals ordered Dimaya removed from the United States. Dimaya appealed and the Ninth Circuit Court of Appeals vacated the removal order, ruling the section that defined “crime of violence” was vague and violated due process rights of those detained and was therefore unconstitutional.

Associate Supreme Court Justice Neil Gorsuch will likely cast the tie-breaking vote, a fact made apparent during Monday’s oral arguments. Gorsuch energetically questioned Edwin Kneedler, the deputy solicitor for the Department of Justice, as to whether the government was asking the courts to do the job of the U.S. Congress: deciding which laws qualify as “crimes of violence” for deportation purposes. For Gorsuch, this seemed to boil down to a violation of the separation of powers doctrine by having the courts do the legislature’s job. That job is to write the law.

“How would I go about deciding what an ordinary case would be,” asked Gorsuch of Kneedler, to press his point that judges would be making determinations that might be better left to legislatures. “I’d want to have hearings,” Gorsuch continued. “So wouldn’t that be a legislative issue?”

Kneedler did not appear to have a direct answer ready for Gorusch.

If Gorsuch is indeed the tie-breaking vote in this case, we may have Justices Elena Kagan and Sonia Sotomayor to thank for bringing him to vote on behalf of due process rights. Both Kagan and Sotomayor grilled Kneedler, playing off each other’s questions, with Kagan as the pragmatist and Sotomayor as the Court’s emerging voice of the left.

Together, their questions about the role of the three branches in drafting, enforcing, and interpreting the law—in addition to the argument that using the vague “crimes of violence” to banish someone from the United States constitutes governmental overreach—just might win over the Court’s most gregarious conservative.

Perhaps the best clue that the parties see Gorsuch as the tie-breaking vote was when Dimaya’s attorney, Joshua Rosenkranz, opened his argument by stating that Gorsuch was correct—that this is a case about Congress not doing its job and instead punting to the courts to determine, on a case-by-case basis, which detainees face deportation.

At this point in the proceedings Justice Samuel Alito put both hands on his face in exasperation, apparently tired either of the arguments or of all the attention Gorsuch was paid by the attorneys and justices. Or both.

A decision in the case isn’t likely until later in the spring, and after Monday’s arguments it is not clear how the case will be decided. Should Gorsuch side with the liberal judges, I don’t think he would do so because of a concern about the law not properly protecting the rights of some who face deportation. I think he would do so because Dimaya is the kind of case he can use to moderate his growing reputation as the Court’s most conservative and reactionary justice.