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A federal appeals court in Boston is considering whether reputed mobster James Whitey Bulger can get a fair trial with a judge who used to be the top federal prosecutor. Bulger is scheduled to be tried in June for 19 alleged murders committed during the 1970s and '80s. His lawyers argue that the judge on the case can't be impartial.

And as NPR's Tovia Smith reports, the court could decide any day whether to remove him from the case.

TOVIA SMITH, BYLINE: It's extremely unusual for a federal appeals court to force a judge off a case, but the trial of the notorious mobster Whitey Bulger is nothing if not unusual. Defense attorney JW Carney says Bulger's case cannot be handled by U.S. District Judge Richard Stearns who was a federal prosecutor at the same time that other prosecutors were engaged in a corrupt relationship with Bulger.

JW CARNEY: The trial must be overseen by a judge who is not connected to the most infamous period in federal law enforcement history in Boston.

SMITH: Judge Stearns has twice refused to step aside, insisting that as former chief of the U.S. Attorney's Criminal Division, he was separate from the organized crime task force that was dealing with Bulger and he never knew anything about the case. But Carney doubts that and wants to call Stearns as a witness to bolster claims that Bulger had a deal with prosecutors granting him immunity in exchange for being an informant.

Judge Stearns calls Carney's demands for recusal, quote, "gratuitous and overheated." Carney concedes the judge has not actually shown any bias. But experts say the real issue is whether people think he might.

HARVEY SILVERGLATE: As they say, there are times when you've got to be purer than Caesars' wife. And this is one of those times.

SMITH: Boston attorney Harvey Silverglate says the public is already distrustful since prosecutors' corruption was exposed. And federal law says a judge should be removed not only if there's a conflict but also even if there just appears to be one to a reasonable person - as there does, Silverglate says, in this case.

SILVERGLATE: It certainly raises eyebrows. And you are not only supposed to have justice but the appearance of justice. And if people's eyebrows are raised, it's the wrong judge for the case.

SMITH: But prosecutors in the case accuse the 83-year-old Bulger of delay tactics. Former U.S. Attorney Michael Connolly agrees there's no basis to remove Judge Stearns.

MICHAEL CONNOLLY: There is no evidence of impartiality on the part of Judge Stearns. I mean, there could be another motivation, obviously, in terms of delay.

SMITH: Federal rules on recusal deliberately leave a lot of wiggle room. But NYU law professor Stephen Gillers says it shouldn't be enough for defendants to simply raise questions about bias and then try and get a judge removed because there are questions about bias.

STEPHEN GILLERS: The back-story, which no one will really say, I think, is the litigant really thinks that this judge is a tough law and order judge in a case like this. We really like to have another judge and is looking around for a reason to get another judge.

SMITH: Relatives of Bulger's alleged victims have also accused him of playing games. But some say they're now persuaded that Judge Stearns should go, including Patricia Donahue whose husband Michael was killed in 1982.

PATRICIA DONAHUE: It's like a catch-22 for me, you know? I want to see Bulger going away, but I don't want people to say: Oh, you know, he didn't get a fair trial after the fact.

SMITH: After waiting decades to see Bulger brought to justice, Donahue says she wants to make sure any conviction is airtight. Tovia Smith, NPR News, Boston.

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