A federal judge on Tuesday ordered the White House to restore The Associated Press’s full access to President Trump, finding that the effort to ban the outlet over objections to its coverage violated the First Amendment.

The order dealt a blow to Mr. Trump, who, in a departure from decades of tradition, has moved to leverage access to presidential events as a way of asserting more direct control over how news organizations cover his administration. Trump officials began barring the outlet from physically covering events with the president in February, citing the wire service’s refusal to adopt the administration’s renaming of the Gulf of Mexico to the Gulf of America.

The outlet sued, with the dispute raising profound questions about the independent news media’s role in covering presidential administrations and the lasting implications of Mr. Trump’s efforts to refigure the White House press corps.

In a sharply worded opinion, Judge Trevor N. McFadden of the Federal District Court for the District of Columbia wrote that the Trump administration must “immediately rescind their viewpoint-based denial” of The Associated Press from presidential events.

“The government repeatedly characterizes The A.P.’s request as a demand for ‘extra special access.’ But that is not what The A.P. is asking for, and it is not what the court orders,” he wrote. “All The A.P. wants, and all it gets, is a level playing field.”

Moments after issuing the opinion, Judge McFadden paused his own order from taking effect until Sunday, giving the government five days to file an emergency appeal. The injunction he ordered would stay in place until the case is over, or a higher court intervenes.

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