[dragonwriter]

> And it turns out that “conspiracy” is something that requires the participants to understand that they’re doing something wrong,

Another problem was that the investigation was obstructed (in the broad sense, including crimes like obstruction of justice, witness tampering, etc.), both by people who were charged for that (some convicted and some remaining beyond the reach of US justice), and by Trump, who could not be charged under Justice Department policy which, regardless of its legal correctness, Mueller was bound by.

(And charging Trump after he left office for crimes related to the 2016 campaign would, given the general 5 year statute of limitations for federal crimes, have been difficult – it might be possible to argue that OLC memo on Presidents being beyond federal prosecution was correct and that the same logic tolled statutes of limitations, but that’s a dicey argument to make; obstruction would have been less problematic, but the Trump pardons and other things would also complicate that.)