Nor was the worst of Mueller that he evaded his responsibility to determine whether there was evidence to convict Trump of obstruction. He left the decision to Attorney General William Barr and Deputy Attorney General Rod Rosenstein, ensuring that a stink of cover-up would hang over it.

Mueller’s outlandish inversion of norms in pointing out that he’d failed to prove Trump innocent was not his most egregious contribution to our poisonous politics. Nor was his invitation to Democrats to impeach the president.

No, the worst of Mueller was not what he did but what he failed to do. To identify that, ask yourself whether you really know the extent of Russian interference in our democracy? Mueller didn’t lay out the probity or abuses of intelligence officials who set his investigation in motion. Have you actually got your mind around what they did? No, you have not. For Mueller didn’t bother to look into the origins of the dossier, which was the seed of the scandal and is legitimately suspected to be Russian disinformation. He didn’t investigate how it fell into the hands of media organizations who used it against Trump. He cast no light on whether his old pal, James Comey, or other intelligence bigwigs such as John Brennan and James Clapper, were duped (and by whom) into believing the claptrap it contained.