Executive privilege for me, not for thee. That seems to be President Biden’s position when it comes to one of the hallmarks of the constitutional presidency, the expectation that the private deliberations of the commander in chief are protected from the prying eyes of the public — and even the solons on Capitol Hill. It’s a prerogative that dates back to Washington’s second term, yet one Mr. Biden refuses for his predecessor, President Trump.

Now, though, Mr. Biden is invoking executive privilege for himself against Republicans in the House. The legislators want access to  audio tapes of the president’s interviews with Special Counsel Robert Hur over his handling of classified documents. Mr. Biden demurs, citing “the absence of a legitimate need,” as his White House counsel, Ed Siskel, puts it. He even laments that they might — heaven forfend — be used “for partisan political purposes.”

Perhaps it’s understandable that some three years into his presidency, Mr. Biden has come to see the value of executive privilege. It was another story in the fall of 2021, when he shrugged it off in response to a request from Democrats in Congress. The House January 6 committee was on the hunt for what the Associated Press called “sensitive information” from the Trump administration relating to the attack on the Capitol. 

“President Biden has determined that an assertion of executive privilege is not in the best interests of the United States,” said the White House counsel, Dana Remus, at the time. It was “a risky move,” the AP observed. The Sun was among those warning that “the same constitutional lee in which Mr. Trump is trying to shelter” — executive privilege — might someday “be invoked by a Democratic president, like, say, one Joseph Biden.”

It hardly required a clairvoyant to make that prediction. The need for secrecy in presidential deliberations was acknowledged by the first president as far back as 1796. The House was looking over Washington’s epaulets, demanding he hand over papers disclosing his negotiation tactics with Britain over the just-signed Jay Treaty. The president declined. The “success” of “foreign negotiations,” he explained, “must often depend on secrecy.”

He doubted, too, that the materials demanded “can be relative to any purpose under the cognizance of the House of Representatives, except that of an impeachment.” Washington’s wisdom was an early expression of what would eventually be termed executive privilege, which is not limited to matters of diplomacy. The first president, too, offered a constitutional road map for how the legislature can properly exercise its oversight of the executive branch.

As for Mr. Biden, his newfound appreciation for executive privilege comes as his Justice Department is undermining another hallmark of his office, the presumption of legal immunity for the president’s official acts. In this dispute, now being weighed by the Supreme Court, Mr. Biden’s attempt to prosecute his chief political rival risks further weakening the presidency, with consequences for future holders of the office — or even Mr. Biden himself.

After Mr. Biden presumed to waive executive privilege for his predecessor, Mr. Trump took to the courts, where his cause did not prosper. A federal judge, Tanya Chutkan, who is now presiding over one of Mr. Biden’s prosecutions of Mr. Trump, contended that the “privilege is not absolute,” and “can be overcome by an appropriate showing of public need by the judicial or legislative branch.” Circuit riders sided with Judge Chutkan.

The Supreme Court declined to intervene, but noted that the questions over a president waiving his predecessor’s privilege “are unprecedented and raise serious and substantial concerns.” Mr. Biden justified the move by explaining that Mr. Trump had been trying “to subvert the Constitution itself.” After chipping away at the constitutional protections of his own office, though, Mr. Biden now faces the prospect of a self-imposed political wound.