WASHINGTON — A federal appeals court panel on Thursday halted an outside review of thousands of documents seized from former president Donald Trump’s Florida residence, ruling that a lower-court judge was wrong to appoint an expert to decide whether any of the material should be shielded from criminal investigators.

Trump sought the outside arbiter, known as a special master, after the FBI executed a court-approved search of Mar-a-Lago, his home and private club, on Aug. 8, retrieving more than 13,000 documents related to Trump’s time in the White House. About 100 of the documents were classified, and some contained extremely sensitive government secrets, according to court records.

The appeals court decision was an emphatic win for the Justice Department, and the latest legal loss for Trump, who has gone to court multiple times to try to stop the government from getting access to records or personal information. Just last week, the Supreme Court denied the former president’s request to block a congressional committee from receiving copies of six years of his tax returns, clearing the way for them to be handed over to lawmakers.

The special-master decision, which Trump may appeal to the Supreme Court, means criminal investigators can again access the unclassified documents that were recovered in the search. The Justice Department has said those materials may be important in their probe of the possible mishandling of classified documents, obstruction and destruction of government property at Mar-a-Lago.

An earlier appeals court ruling exempted the documents with classified markings from the special master review.

In addition to potentially slowing down the investigation, the special-master review provided Trump’s lawyers with a public platform to make their arguments about why they believed the Mar-a-Lago search was unfair. While those arguments did not hold much sway with judges, they may have nonetheless buoyed Trump’s political base.

U.S. District Judge Aileen Cannon of Florida agreed months ago to appoint Judge Raymond Dearie of Brooklyn as special master to review the Mar-a-Lago documents, rejecting the Justice Department’s argument that former presidents cannot claim executive privileges after leaving office. Cannon also noted that the FBI took some of Trump’s personal materials that were mixed with the government documents.

But special master appointments are rare, and judges at the U.S. Court of Appeals for the 11th Circuit expressed concern at oral arguments that Cannon’s decision set a troubling precedent: allowing the target of a search warrant to go into court and request a special master that could interfere with an executive branch investigation before an indictment is ever issued.

The judges – two of whom were nominated by Trump – did not back down from that stance in their written opinion Thursday. They said they could not issue an order that would “allow any subject of a search warrant to block government investigations after the execution of the warrant.”

“Nor can we write a rule that allows only former presidents to do so,” the Thursday opinion read. “Either approach would be a radical reordering of our caselaw limiting the federal courts’ involvement in criminal investigations. And both would violate bedrock separation-of-powers limitations.”

During oral arguments, government attorney Sopan Joshi called the decision to name a special master an “intrusion” on the executive branch.

But James Trusty, an attorney for Trump, said the special master appointment didn’t significantly hamper the government’s criminal probe. Trusty said the search of Mar-a-Lago was conducted in a “carte blanche” manner, with agents taking personal items including golf shirts and a photo of singer Celine Dion.

In their opinion, the judges rebuked a central part of the argument by Trump’s legal team: that the Presidential Records Acts allowed Trump to categorize presidential documents as personal ones, creating the need for a special master to determine whether personal documents should be shielded from investigators.

The judges conceded that the search of a former president’s property is “indeed extraordinary … but not in a way that affects our legal analysis or otherwise gives the judiciary license to interfere in an ongoing investigation.”

Ultimately, the judges said that the status of the documents as personal or presidential should not determine whether a special master is needed. The warrant to search Mar-A-Lago, the opinion said, was properly approved by a judge; whether Trump was lawfully in possession of the seized documents could be assessed in future legal proceedings.

“The magistrate judge decided that issue when approving the warrant. To the extent that the categorization of these documents has legal relevance in future proceedings, the issue can be raised at that time,” the opinion reads. “All these arguments are sideshow.”

Dearie’s review was expected to conclude this month. He has not made any recommendations to Cannon about whether any documents should be shielded from criminal investigators. But during public hearings, he has expressed deep skepticism that Trump could claim privileges over large swaths of the documents.

“My view is you can’t have your cake and eat it,” he said at a September hearing, after Trump’s attorneys suggested that Trump may have declassified some of the sensitive seized materials but stopped short of saying that he actually did.

The Mar-a-Lago probe is one of three criminal investigations involving Trump that have built momentum over the past year. The Justice Department is also investigating the role of Trump and his allies in efforts to overturn the 2020 election results, including any potential involvement in the bloody riot at the U.S. Capitol on Jan. 6, 2021, as members of Congress and Vice President Mike Pence were formally tallying President Biden’s electoral victory.

Attorney General Merrick Garland recently appointed a special counsel to oversee both those investigations, saying it was important to avoid any potential conflict of interest for the Justice Department as Trump launches a new bid for the White House and Biden says he plans to run as well.

In addition, Fulton County District Attorney Fani Willis is investigating the role of Trump and his allies in trying to overturn Biden’s election victory in Georgia in 2020.

The appeals panel that issued Thursday’s opinion included Judge William H. Pryor, the former attorney general of Alabama, who was nominated to the bench by President George W. Bush and who Trump considered for a Supreme Court appointment while he was in the White House.

The other two judges on the panel, Andrew L. Brasher and Britt C. Grant, are Trump nominees. They also were on the three-judge panel that ruled against Trump earlier this fall on limited aspects of the special master appointment, restoring access for criminal investigators to the 103 documents with classified markings.

In considering the arguments by Trump’s lawyers, the judges wrote, “we are faced with a choice: apply our usual test; drastically expand the availability of equitable jurisdiction for every subject of a search warrant; or carve out an unprecedented exception in our law for former presidents. We choose the first option. So the case must be dismissed.”

The judges said the seizure of personal items in a court-approved search did not necessitate the appointment of a special master.

“While Plaintiff may have an interest in these items and others like them, we do not see the need for their immediate return after seizure under a presumptively lawful search warrant,” the Thursday opinion reads.