In her ruling, U.S. District Judge Aileen Cannon in West Palm Beach, Florida, said the special master will be tasked with reviewing documents the FBI seized that could be subject not just to attorney-client privilege, but also to executive privilege.
The Justice Department has said in court filings that highly classified government documents, including some marked "Top Secret," were discovered in Trump's personal office during the FBI execution of the court-approved search warrant.
"The Government is temporarily enjoined from further review and use of any of the materials seized from Plaintiff's residence on August 8, 2022, for criminal investigative purposes pending resolution of the special master's review process as determined by this Court," the order said.
Cannon's order made an exception for review and use of the materials for "intelligence classification and national security assessments."
Prosecutors had opposed Trump's demand to review the documents for "executive privilege," setting forth that there is no precedent for a former executive to bar review of materials by a sitting resident and administration, especially when the government has determined the need is urgent.
A detailed list of what was seized also showed Trump held on to more than 11,000 unclassified government records that he claims are his to keep -- but legally are owned by the National Archives.
"In addition to being deprived of potentially significant personal documents, which alone creates a real harm, plaintiff faces an unquantifiable potential harm by way of improper disclosure of sensitive information to the public," wrote Cannon, who was appointed by Trump in 2020 just months before he left office.
The judge gave both sides until Friday to come up with a list of candidates for the role of special master.
This report was prepared using information from Reuters and Agence France-Presse.