Presidents in the wake of Mr. Nixon were circumspect in their invocations of executive privilege, not wanting to be associated with Watergate. The one exception was Bill Clinton, who used it over a dozen times; in one instance, he tried to block two White House officials from testifying in the Monica Lewinsky investigation. Ken Starr’s impeachment referral to Congress actually enumerated this as a reason for impeachment — arguing that Mr. Clinton had abused executive privilege.

This use of executive privilege — to shield personal wrongdoing — had strong echoes of Mr. Nixon, and for that reason attracted a lot of scrutiny, not simply in Congress but also in the courts. He lost his battle to shield his aides from testifying and ultimately eroded his claim to secrecy more generally. By looking profligate and personal in his use of the privilege, he cried wolf too many times, and he found it much harder to use it in circumstances, like the pardons for former members of the Armed Forces of National Liberation, known by its Spanish acronym F.A.L.N., which waged a violent campaign for the independence of Puerto Rico (President Clinton offered them clemency in 1999 because, he said, their sentences were out of proportion with their offenses).

Presidents George W. Bush and Barack Obama were clearly influenced by the Clinton experience and invoked privilege only sparingly (six times for Bush, one for Obama). That was on par for the post-Nixon presidents (Presidents Gerald Ford, Jimmy Carter and George H.W. Bush each invoked it only once; President Reagan, three times). President Trump, by contrast, is well on his way to following the Nixon-Clinton precedents. Neither ended particularly well.

There is a deep reason for that. Americans can tolerate some secrecy, particularly when it is rooted in protection of the public’s interests. But when the claims appear to hide wrongdoing, they begin to curdle. Instead of safeguarding high-minded principles, the claims look personal, and more like something a king would do. And that is just about what Mr. Trump’s latest invocations look like.

In the teeth of a redacted report that all but labels Mr. Trump a criminal, the president’s claim to try to block the full Mueller report from coming out looks like he is trying to shield evidence of his wrongdoing. The report says: “Substantial evidence indicates that the president’s attempts to remove the special counsel were linked to the special counsel’s oversight of investigations that involved the president’s conduct — and, most immediately, to reports that the president was being investigated for potential obstruction of justice.”