I’m tempted to respond that Mueller was charged with investigating Russian interference in the 2016 campaign in its totality, not just Trump’s possible role in it. But Dershowitz would have an answer to that: You don’t need a special prosecutor for that. The DOJ’s regular personnel can handle it — and did, until Trump dropped the axe on Comey in May 2017 and Rod Rosenstein stepped in to appoint Mueller. The rationale for appointing a special counsel from outside the Justice Department is to eliminate a conflict of interest that may arise when the Department is asked to investigate one of its own superiors, either the Attorney General or the president. Deputies can’t conduct a fair investigation of their own boss, the theory goes, so the Department must look beyond its own walls for a lawyer whose career doesn’t depend upon the president’s or AG’s favor. Someone not quite fully independent of the executive branch but at least more independent than regular Justice Department employees.

But that brings us back to Dershowitz’s point. If the president can’t be indicted, how was there a conflict of interest in the first place? Why couldn’t Rosenstein have declared in May 2017 that, as a matter of DOJ policy, the president won’t be charged and then let Chris Wray pick up where Comey left off? Why’d we need to endure two years of Mueller-related suspense only to be told at the end that not only couldn’t the special counsel formally accuse Trump by indicting him, he couldn’t *informally* accuse him since it would be unfair to cast aspersions on someone with no legal means of rebutting them?

The answer, I think, is that only a special counsel could have restored public faith in the investigation. If Rosenstein had let regular DOJ employees continue the probe after Comey was fired, the outcome would have been savaged either way. If Trump had been accused of a crime, Wray and his deputies would have been accused of taking revenge for Comey’s termination. If Trump had been exonerated, they would have been accused of whitewashing the president’s guilt out of fear for their own careers. There was no option available to Rosenstein that wouldn’t have led to partisans from one or the other screeching about politicization at the end, but bringing in an outsider who was — at first — respected by both sides was probably the most “neutral” thing he could have done. And it worked to Trump’s benefit in the end. Does anyone believe that Wray’s determination that Trump’s actions didn’t amount to conspiracy with Russia would have been received as credulously by the left as Mueller’s determination was?

I’d also entertain the argument that a special counsel is needed in cases where someone *close* to the president is being investigated even if the president himself isn’t. If we’re worried that the DOJ can’t/won’t vigorously pursue its own boss for fear of reprisal, logically we should also worry that it can’t/won’t vigorously pursue people whom its boss cares about. Donald Trump Jr and Jared Kushner were both in the crosshairs of the special counsel. I feel more confident about the decision not to indict them for conspiracy coming from the quasi-independent Mueller than I would have had that decision come from Chris Wray. That’s the virtue of having a special counsel in this case.

There’s one other possibility. Although it’s true that Mueller couldn’t have indicted Trump per the DOJ’s policy about sitting presidents, theoretically he could have informally accused him — saying, e.g., that in his judgment probable cause exists to believe Trump obstructed justice. Bill Barr himself raised that possibility in his interview with CBS. That is, the fact that Mueller couldn’t charge the president doesn’t mean that the investigation was worthless; Mueller could have gathered the evidence, made an informal conclusion about guilt, and then handed the issue back to the DOJ so that it could charge Trump after he returned to private life. That would have been problematic inasmuch as Mueller’s judgment about probable cause likely would have leaked, casting a legal cloud over Trump’s presidency (which is precisely why Mueller refused to make even an informal accusation), but it’s a potential answer to Dershowitz’s question. The special counsel could have engineered a delayed prosecution of the president.

Two related exit questions for you. One: Why wasn’t the question of whether Trump could be indicted definitively settled by Rosenstein and the DOJ up front? Why did we have to linger in suspense for so long? Two: To turn Dershowitz’s question around a bit, why did we let the president be investigated by someone whom the president (probably) has the power to fire? Mueller was more independent than regular DOJ personnel but not totally independent. Trump likely could have stopped the investigation at any time per his constitutional power under Article II. Realistically, the only way to resolve knotty questions about the executive branch investigating itself is to remove the whole issue to Congress. If Congress wants to investigate the president, accuse him of a crime, and then remove him from office because of it, the DOJ can take the baton and indict him afterward — but not before. Going forward, the executive branch should always follow the lead of the legislature on presidential investigations, not vice versa.