A federal judge has granted Donald Trump’s request to have a “special master” appointed to review documents the FBI seized from his Mar-a-Lago estate that could be subject to privilege protections in the investigation into unauthorized retention of government secrets.

The order from the US district court judge Aileen Cannon, a Trump appointee, also temporarily barred the justice department from reviewing the documents for its criminal inquiry until the special master completes its work, in a decision that marked a procedural victory for the former president.

Cannon wrote in her 24-page ruling, however, that the Office of the Director of National Intelligence (ODNI) could continue to review the seized materials for its separate inquiry into whether Trump’s retention of documents with classified markings at Mar-a-Lago risked national security.

Cannon gave Trump’s legal team and the DoJ until Friday to file a proposed list of special master candidates.

The DoJ is likely to appeal the decision to the US court of appeals for the 11th circuit, officials said, though in the meantime it will almost certainly delay the investigation into potential violations of the Espionage Act and potential obstruction of justice.

Still, the ruling does not change the underlying facts of the investigation that led to the FBI executing a search warrant at Mar-a-Lago last month – that Trump was in unauthorized possession of highly sensitive government documents that could yet result in criminal charges.

Cannon disagreed with the DoJ’s opposition to appointing a special master on several points, including its main argument that Trump lacked standing for such a motion because he had no “possessory interest” in White House records since he was no longer president, according to the filing.

The judge wrote that she believed the government had misinterpreted the appellate court precedent, writing that Trump did not need to conclusively prove ownership of the seized property, but only that he had a colorable right, or plausible legal claim, to possess some of the materials.

Cannon also disagreed with the DoJ’s argument that another review of the seized materials by a special master was unnecessary after the FBI’s so-called filter teams screened the documents for potentially privileged material in the two weeks it took Trump’s lawyers to file their motion.

The judge, as she previewed in court last week, noted that the DoJ’s investigative team had inadvertently seen potentially privileged material on at least two occasions that she said raised questions about the adequacy of the FBI’s filter team review.

Cannon additionally wrote that she disagreed with theDoJ’s argument that Trump could not seek a special master to set aside documents potentially protected by executive privilege from an investigation being conducted by the DoJ, part of the executive branch.

The judge wrote she believed the government was overstating the law, saying – as she corrected the DoJ’s lawyer in court – that in the landmark case of Nixon v General Services Administration 1977, the US supreme court left open the concept that a former president’s assertion of executive privilege might be stronger than a current president’s waiver of it.

In this case, Cannon’s ruling referred to the possibility of Trump asserting executive privilege over certain documents and preventing the DoJ from using them in its investigation, even if Joe Biden, the current president, declined to assert privilege. The law over what happens in such a dispute has not been conclusively settled.

“Even if any assertion of executive privilege by Plaintiff ultimately fails in this context, that possibility, even if likely, does not negate a former President’s ability to raise the privilege as an initial matter,” Cannon said in her decision.

But the judge also made no mention of the Presidential Records Act mandating the documents belong at the National Archives.

Cannon gave the DoJ and Trump’s lawyers until Friday to submit a joint filing for candidates to serve as the independent arbiter, known as special master – typically a retired lawyer or judge – to weed out any attorney-client or executive-privileged documents from the evidence cache.

A special master was used, for instance, to review materials seized in the searches of the homes and offices of two of Trump’s former attorneys – Rudy Giuliani and Michael Cohen.

The DoJ had opposed Trump’s motion, arguing that it would delay its criminal investigation, and in a court hearing last week in West Palm Beach, Florida, sounded alarm that a special master process could give Trump access once more to highly sensitive and classified documents.

Trump’s former attorney general, Bill Barr, also called the special master request a “waste of time”, adding: “Even if they are subject to executive privilege, they still belong to the government.

“And any other documents that were seized … those were seize-able under the warrant,” Barr said.

In a reaction posted on Twitter, Neal Katyal, former US acting solicitor general, wrote that the appointment of a special master wouldn’t derail the federal investigation but that this decision “sets a terrible precedent”.

“Even though this judge’s order appointing a special master won’t stop the very serious Trump stolen docs investigation, having been the decider of whether DOJ should appeal various cases in the past, I think DoJ has to appeal here,” Katyal tweeted, adding: “That’s what I’d do.”