The Justice Department is expected to release on Friday a partly redacted version of the affidavit that federal investigators used to obtain a search warrant for former President Donald J. Trump’s Florida residence — a disclosure that could have significant legal, political and historical implications.
On Thursday, a federal judge in Florida surprised department officials by ordering them to release to the public the unsealed document by noon on Friday. The government has not said when it will post the affidavit.
It is not clear how extensive the redactions will be, but the document will provide insights into how the Justice Department came to pursue classified documents that ended up at Mr. Trump’s Mar-a-Lago club after he left the White House and the criminal investigation that stemmed from that effort.
The Justice Department had proposed extensive redactions in an effort to shield witnesses from intimidation or retribution if the details were made public.
In its most complete form, the document would disclose important, and potentially revelatory, details about the government’s justification for taking the extraordinary step of searching Mar-a-Lago on Aug. 8.
Last week, Bruce E. Reinhart, a federal magistrate judge in Florida, surprised prosecutors by saying he was inclined to release portions of the affidavit at the request of news organizations, including The New York Times, after the government proposed redactions.
Disclosing even a partial version of the affidavit would be highly unusual. Such documents, which typically include evidence gathered to justify the search, like information provided by witnesses, are almost never unsealed before the government files criminal charges. There is no indication the Justice Department plans to file charges anytime soon.
Judge Reinhart had acknowledged that extensive redactions could render the release of the final document meaningless.
“I cannot say at this point that partial redactions will be so extensive that they will result in a meaningless disclosure, but I may ultimately reach that conclusion after hearing further from the government,” he wrote in an order issued on Monday.
Justice Department officials had suggested they would push hard to scrub anything that could expose witnesses in the case to intimidation or retribution by Mr. Trump’s supporters. After the search at Mar-a-Lago, the F.B.I. reported a surge in threats against its agents; an armed man tried to breach the bureau’s Cincinnati field office before being killed in a shootout with the local police.
Mr. Trump’s legal team has not yet seen the affidavit. The government is not required to show it to them. But they had not opposed efforts to unseal it nor taken a position in court that it should be released.
The full affidavit is likely to contain telling details about the Justice Department’s inquiry into whether Mr. Trump mishandled national defense documents and obstructed a federal investigation.
Typically, the courts have allowed redactions that protect “sources and methods” of current investigations. Judge Reinhart is unlikely to stray from that practice.
Legal experts said he was all but certain to permit redactions of portions that mention the government’s witnesses, or parts that explicitly describe the reasons prosecutors believe there was probable cause to find evidence of a crime at Mar-a-Lago, which could compromise the investigation.
Mr. Trump’s legal team has already revealed some details about the government’s efforts to retrieve the documents — among them, meetings with prosecutors and the issuance of federal subpoenas — in a motion filed this week seeking a special master to oversee a review of the seized documents.