Washington — A federal appeals court in San Francisco weighed Tuesday whether President Trump can continue with his deployment of California's National Guard in Los Angeles to protect federal immigration authorities during enforcement operations and appeared skeptical of the state's arguments against the president's mobilization of more than 4,000 troops.

The three-judge panel on the U.S. Court of Appeals for the 9th Circuit heard arguments on a Justice Department request for it to halt a district judge's order that required Mr. Trump to return control of the National Guard to Gov. Gavin Newsom while the court fight moves forward. Newsom, a Democrat, objects to the federalization of the National Guard in Los Angeles.

Brett Shumate, an assistant attorney general with the Justice Department, said Mr. Trump's decision to call National Guard troops into federal service under a law known as Title 10 is unreviewable by courts, regardless of the facts of the case. If the panel were to side with California, he warned, "it puts Article III judges on a collision course with the commander-in-chief."

Shumate said that California's interpretation of the law is "dangerous" and would allow Newsom to issue a "pocket veto" of any future orders from Mr. Trump. He said it's "essential" that the district court's injunction be lifted and said leaving it intact would put "lives and property at risk." 

Shumate said that if the 9th Circuit declines to halt the district judge's order, it should allow the Justice Department time to seek emergency relief from the Supreme Court.

But Sam Harbourt, a deputy solicitor general for California, said Mr. Trump's order calling the National Guard into federal service sweeps too broadly. He told the court that the president failed to consider any "modest measures" to quell protests in Los Angeles before taking the "grave and extraordinary step" of calling forth the National Guard.

Harbourt told the judges that Mr. Trump circumvented Newsom when he unilaterally decided to deploy the California National Guard to Los Angeles and warned that the continued presence of troops in city streets would escalate tensions and the risk of violence.

The three judges considering the Trump administration's request for a stay during the appeal are Judges Mark Bennett, Eric Miller and Jennifer Sung. Mr. Trump appointed Bennett and Miller during his first term, and former President Joe Biden tapped Sung for the 9th Circuit.

Early on, Bennett appeared skeptical of the Trump administration's position that courts cannot review the president's decision to federalize the National Guard and should not second-guess his military judgments. But as the arguments continued, all three judges pressed Harbourt on his position. 

Bennett asked where in the law there is a requirement for the president to have considered alternative measures before exercising control of the National Guard. He also probed Harbourt on his claim that Title 10 required Mr. Trump to consult with Newsom before calling the California troops into federal service.

Miller cited a state law that he said effectively makes the adjutant general of the California National Guard a "substitute" for the governor. Mr. Trump had directed Defense Secretary Pete Hegseth to effectuate the federalization of Guard troops, and he then issued memoranda to the adjutant general to transfer authority over the Guard from the state to the federal government.

The case landed before the 9th Circuit after U.S. District Judge Charles Breyer ruled last week that Mr. Trump's actions in deploying the National Guard to respond to protests against immigration raids in Los Angeles were illegal and blocked the administration from deploying the troops in the city.

The Trump administration swiftly appealed that decision, and the 9th Circuit panel issued a temporary administrative stay while it took more time to consider the issue. 

The legal battle involves whether the president exceeded his authority when he invoked Title 10 to call forth the California National Guard in response to protests in California's largest city. Demonstrations broke out earlier this month after immigration agents conducted raids across Los Angeles as part of the administration's efforts to crack down on immigration and execute mass deportations.

Title 10 lays out three circumstances under which the National Guard can be called into federal service: when the U.S. is invaded or in danger of invasion by a foreign nation; when there is a rebellion or danger of a rebellion against the authority of the U.S.; or when the president is unable with the regular forces to execute the laws. It then says that orders "shall be issued through" the governor.

Mr. Trump said in his June 7 memorandum ordering the deployment of 2,000 National Guard members that the protests in Los Angeles "constitute a form of rebellion," which allowed him to federalize the National Guard and bypass Newsom. An additional 2,000 troops were brought under federal command. Roughly 700 active-duty U.S. Marines have also been mobilized to the area to protect federal property and immigration agents during arrests.

In his decision, Breyer rejected the president's claim that the demonstrations are a "rebellion," writing that he is "troubled by the implication inherent in defendants' argument that protest against the federal government, a core civil liberty protected by the First Amendment, can justify a finding of rebellion."

The protests, the judge said, "fall far short" of rebellion, and the administration failed to identify a "violent, armed, organized, open and avowed uprising against the government as a whole." The judge's order did not address the president's mobilization of the Marines to Los Angeles.

In filings with the 9th Circuit, the Trump administration argued that courts do not have a role in reviewing the president's decision to deploy the troops. Even if courts could review his decision to call the National Guard into federal service, the Justice Department said the president had ample reason to determine that the protests in Los Angeles rose to the level of a "danger" of rebellion, one of the conditions laid out in Title 10.

"The district court's order improperly impinges on the commander in chief's supervision of military operations, countermands a military directive to officers in the Held, and puts federal officers (and others) in harm's way," .

Newsom and California officials told the 9th Circuit in that Breyer's order should be left undisturbed, as it restored the status quo in place before Mr. Trump's June 7 memorandum.

"Considered individually, defendants' legal arguments are meritless. Considered in the aggregate, they are terrifying," California lawyers wrote. They said that the administration's interpretation of Title 10 "would empower the president to commandeer a state's National Guard based merely on evidence that some civilians opposed his authority, disobeyed his commands, or presented operational difficulties for civil law enforcement officials — and without any input from (or even notice to) the governor. "

They said that "unchecked power" could be used in any context, "not just where civilians are protesting immigration enforcement, but also where they are protesting other policies of a federal administration, or protesting in advance of a hotly contested federal election."

"Collectively, defendants' arguments would sideline the judiciary, ignore Congress's limitations, and trample over the states' sovereign interest in their own militias," California's attorneys argued.

Among the issues before the 9th Circuit panel is whether the Trump administration properly notified Newsom of its order calling the National Guard into federal service. The Justice Department argued in lower court proceedings that it did because two memos calling up the National Guard went through California's adjutant general, who runs the California National Guard, and not Newsom's office, as California has argued is necessary.

That argument, Breyer wrote, "strains credibility" because Congress mandates that the National Guard requires the notice to be "issued through the governors." 

• California