The Supreme Court wrestled Monday with what Congress intended in a 1978 law about government surveillance, and how it applies to a lawsuit from three Muslims in California who say the FBI infringed on their religious rights in 2006 and 2007.

The case hinges on the government’s longstanding power to keep sensitive national security information from being exposed in court — called the “state secrets” privilege — even if that ultimately means a lawsuit must be dismissed to protect that information.

A district court had dismissed claims in the lawsuit when the government claimed that privilege over information about investigations and methods of surveillance. But the U.S. Court of Appeals for the 9th Circuit revived the lawsuit, and ruled that the judge should review the evidence in secret and determine whether the domestic surveillance was lawful.

Some of the justices’ questions during oral argument Monday floated the possibility of a limited decision that would send the case back to lower courts for another look — which might for now keep alive the lawsuit against the FBI and leave broader legal questions for another time.

The attorney for the Muslims told the justices that Congress essentially carved out an exception to the state secrets privilege in the same law that created a special secret court to oversee government surveillance, known as the Foreign Intelligence Surveillance Act.

Ahilan Arulanantham said Monday that is what Congress wanted when it wrote the law against a backdrop of abuses surveillance of Vietnam War protesters and Martin Luther King Jr.

“The courts get to find out if the government is breaking the law or not,” Arulanantham said. “But if you ever want to disclose to the plaintiffs, to go beyond just the court, and go to us, and to the public, now the government has the ability to argue that that’s not permitted in the interest of national security.”

The FBI countered Monday that the 9th Circuit decision would substantially weaken the government’s ability to safeguard national security information. Deputy Solicitor General Edwin Kneedler argued that the provision was not intended for a judge to decide whether the government surveillance was lawful.

Instead, the provision was only to allow judges to review evidence if the government sought to use in a legal proceeding. Kneedler told the justices that it would be surprising if Congress decided to override the state secrets privilege in the middle of provisions that dealt with when the government wants to use evidence in court, not keep it out.

“I think the Court should insist upon some sort of clear statement or clear indication that Congress intended to abrogate a privilege that is, in our view, critical to the president’s exercise of his Article II powers,” Kneedler said.

Chief Justice John G. Roberts Jr. voiced similar concerns. “The sentence we’ve been talking about is 20 lines, and squirreled away in there are these few words that you’re relying on for displacement of the state secrets privilege, for a reading of FISA that has enormous consequences for state secrets for national security,” Roberts said to Arulanantham.

“And I just wonder, why would Congress put such significant language, stuck in this provision? Isn’t that an oblique way to have the consequences you’re ascribing to that language?” Roberts said.

Justices Stephen G. Breyer, Sonia Sotomayor, and Brett M. Kavanaugh were among the justices who asked questions that contemplated sending the case back to the appeals court.

Kavanaugh, in a line of questioning that touched on the scope of the state secret privilege, suggested that the court could rule in a way where “all these kinds of issues can be fleshed out and come back to us where that’s the central focus of the case.”

“I feel like it’d be doing a drive-by in this case on a massively important issue if we get into that,” Kavanaugh said.

The case stems from a paid informant for the FBI who infiltrated the Muslim community in Orange County, Calif., for more than a year. The lawsuit, filed in 2011, contends that the informant later said the purpose of the operation was to gather information on Muslims because of their religion.

The United States invoked the state-secrets privilege over information concerning whether any particular individual was the subject of an FBI counterterrorism investigation, the reasons for any such investigation and “the particular sources and methods used (including any undisclosed electronic surveillance).”

The FBI in the case told the justices that the 9th Circuit ruling “creates a roadmap for inventive litigants to avoid the state-secrets privilege whenever electronic surveillance allegedly is involved.”