The U.S. Supreme Court may be nearing a decision on whether to hear a case brought against Colorado by two neighboring states over marijuana legalization.

Supreme Court justices were scheduled to meet privately Friday to discuss the case, which was filed in 2014 by the attorneys general in Nebraska and Oklahoma.

The justices won’t have decided at the meeting whether to upend legalization in Colorado, as the lawsuit requests. Instead, the justices must decide first whether even to take up the case.

Their decision could be announced as early as Monday. But Sam Kamin, a professor at the University of Denver who specializes in marijuana law and who has followed the lawsuit closely, said there are no guarantees the justices even got around to talking about the case Friday. The court twice before had scheduled to discuss the case at conferences, only for the discussion to be pushed back.

“We just don’t know what’s going on behind the scenes,” Kamin said.

In the lawsuit, Nebraska and Oklahoma ask the Supreme Court to overturn Colorado’s system for licensing marijuana businesses, which was part of the state’s 2012 initiative that legalized cannabis. The neighboring states argue the commercialization allowed in state law impermissibly conflicts with federal law, and they say marijuana flowing across Colorado’s borders has created a burden for them.

Colorado officials defended the law’s legality — saying it doesn’t negate the federal government’s ability to criminalize pot. The Obama administration also urged the Supreme Court not to take the case.

Because the case involves a dispute between states, the lawsuit was filed directly to the Supreme Court. Four justices must vote in favor of hearing the case for the court to take it. If that happens, it starts a likely years-long process of filings and arguments before a final decision is reached.

Kamin said it is unclear what impact the death of Justice Antonin Scalia will have on the case. At a speech in Boulder a couple of months before the suit was filed, Scalia seemed to support its general argument.

“The Constitution contains something called the Supremacy Clause,” he said about marijuana, referencing the provision that says federal law tops state law when the two are in direct conflict.

Kamin said the Supreme Court may shy away from taking big cases while operating with only eight justices.