What did Donald Trump do today?

He confessed to obstruction of justice.

After a full day of refraining from public comment on the news that Michael Flynn had struck a plea bargain with the special counsel, Trump took to Twitter in what seems to have been an effort to insulate himself from the political fallout. Trump said that Flynn's actions were "lawful"--which contradicts Flynn's own statement on the matter--but also that he "had to fire General Flynn because he lied to the Vice President and the FBI."

It is not a crime to lie to Mike Pence, but it is a crime to lie to the FBI. And as legal experts were quick to point out, since Trump fired FBI Director James Comey over his unwillingness to "let Flynn go," the fact that he apparently knew Flynn had lied to the agency that Comey led means that this attempt to help Flynn escape prosecution was obstruction of justice.

Belatedly realizing Trump's mistake, the White House responded with two defenses. The first was that Trump was "simply paraphras[ing] what Ty Cobb said yesterday." But Ty Cobb, a lawyer working on Trump's defense, said no such thing, since it would implicate his client in obstruction of justice.

The second, offered by anonymous sources hours after the initial response, was that the tweet had actually been "crafted" by John Dowd, another lawyer working on Trump's personal legal defense team. But the White House itself was careful not to go on record with any statement denying Trump's authorship, since that would raise questions about why one of Trump's lawyers was implicating him in obstruction of justice. 

The only two presidents in recent history to be impeached or seriously threatened with it, Bill Clinton and Richard Nixon, both faced charges of obstruction of justice.

Why does this matter?

• It's bad, and impeachable, if the president obstructs justice in furtherance of a criminal conspiracy.

• People innocent of wrongdoing do not need to change their story.