There is much to be said for all this, none of it happy-making. One thing that can be said with clarity is that, under the ethics rules cited by Sessions, Mueller has a long-term relationship with Comey that “may result in a personal … conflict of interest, or the appearance thereof.”

Mueller is therefore disqualified. I hope and suspect that Mueller, whom I believe to be a partisan of the rule of law, will see this. If he doesn’t, I hope Deputy Attorney General Rod Rosenstein will.

Experienced attorneys prefer rule-orientation and properly fear self-justification, a ubiquitous flaw in even the best of men. There is no way Comey is anything but a central witness in this investigation — if not a subject. Even less is there a way Mueller can be expected to evaluate Comey’s credibility with the fresh neutrality, arm’s-length curiosity, and objective sharp eye his job demands.