Is Robert Mueller conflicted in Trump probe?

Which brings up an intriguing legal question. Comey is a good friend of special counsel Robert Mueller — such a good friend, for about 15 years now, that the two men have been described as “brothers in arms.” Their work together during the controversies over Bush-era terrorist surveillance has been characterized as “deepening a friendship forged in the crucible of the highest levels of the national security apparatus after the 9/11 attacks,” after which the men became “close partners and close allies throughout the years ahead.”

Now Mueller is investigating the Trump-Russia affair, in which, if the increasing buzz in the case is correct, allegations of obstruction against the president will be central. And central to those allegations — the key witness — will be the prosecutor’s good friend, the now-aggrieved former FBI director.

Is that a conflict? Should a prosecutor pursue a case in which the star witness is a close friend? And when the friend is not only a witness but also arguably a victim — of firing — by the target of the investigation? And when the prosecutor might also be called on to investigate some of his friend’s actions? The case would be difficult enough even without the complicating friendship.

This is by no means a definitive answer, but I put that question to five Washington lawyers Sunday — lawyers in private practice, on Capitol Hill, in think tanks, some of them veterans of the Justice Department.