A quarter-century later, President Bill Clinton was impeached by the House for, among other things, having “prevented, obstructed and impeded the administration of justice” and for having “engaged personally, and through his subordinates and agents, in a course of conduct or scheme designed to delay, impede, cover up and conceal the existence of evidence and testimony.”

Now let’s see if those descriptions apply to President Trump.

On Saturday morning, in the wake of the bombshell guilty plea by Michael Flynn, the president’s former national security adviser, for lying to F.B.I. agents about his communications with Russian officials late last year, Mr. Trump tweeted, “I had to fire General Flynn because he lied to the Vice President and the FBI.”

Recall that the original justification for Mr. Flynn’s firing was simply that he had misled Vice President Mike Pence; otherwise he had done nothing wrong. That’s the case Mr. Trump made the day after Mr. Flynn’s firing, when he allegedly tried to shut down the F.B.I.’s inquiry into his campaign’s connections with Russian officials by telling James Comey, who was then the F.B.I. director, in a private Oval Office meeting, “I hope you can see your way clear to letting this go, to letting Flynn go.”

In May, Mr. Trump fired Mr. Comey, telling Russian officials in the Oval Office the next day that firing Mr. Comey had relieved “great pressure” on him, and referring to Mr. Comey as a “nut job.” In an interview with NBC, Mr. Trump said, “When I decided to just do it, I said to myself, I said, ‘You know, this Russia thing with Trump and Russia is a made-up story.’”

It was bad enough for the president to attempt to interfere in any way with a law enforcement investigation of one of his top aides. But with Saturday’s tweet, Mr. Trump admitted that he knew Mr. Flynn had committed a federal crime at the time he fired Mr. Comey for refusing to stop investigating him. To most people with a functioning prefrontal cortex, it sure sounds like Mr. Trump is admitting to “interfering or endeavoring to interfere with the conduct of investigations” and to “impeding the administration of justice.”