On Wednesday afternoon, the Justice Department selected Robert Mueller III as special counsel to investigate any links or coordination the Trump campaign had with Russia as part of that country's effort to interfere in last year's presidential election.

"Special Counsel Mueller has agreed to resign from his private law firm in order to avoid any conflicts of interest with firm clients or attorneys," a Justice Department statement noted.

It so happens that Mueller had been working at WilmerHale, which represents former Trump campaign manager Paul Manafort, the president's daughter Ivanka Trump and Trump son-in-law Jared Kushner — people who might be witnesses, or more, in the course of Mueller's high-profile investigation.

That turn of events has got people asking whether Mueller's previous role poses conflicts for his current one. So NPR consulted with ethics experts to get their take.

First, the legal ethics. A spokesman at WilmerHale told NPR that Mueller "had no role whatsoever in the representation of any client in connection with the Russia inquiry, and he has no confidential information with respect to such matters." Same goes for Aaron Zebley, who was one of Mueller's top aides, and James Quarles, another WilmerHale partner joining Mueller's special counsel team, the law firm spokesman said.

To Stephen Gillers, a professor of legal ethics at New York University School of Law, the inquiry ends there.

"If he was not involved in the representation at all, then there's no problem," Gillers said. "Once he leaves the firm, he's purged from any conflicts the firm had."

Next, there are government ethics rules. Under those rules, a government employee needs to consider whether a reasonable person could question his or her impartiality because of a "covered relationship" with an organization, where that organization represents a party in a case or an investigation. "Then," the rules say, according to Washington University School of Law Professor Kathleen Clark, "don't participate unless a designee in an agency makes an independent determination" that it passes muster.

Reached Thursday, the Justice Department had no immediate comment on who, if anyone, conducted that analysis: Deputy Attorney General Rod Rosenstein; Assistant Attorney General Lee Lofthus, who runs the unit that handles administration of the Justice Department; or someone else.

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