James "Whitey" Bulger's case is returning to court — minus the notorious Boston gangster himself.

A three-judge panel of the 1st U.S. Circuit Court of Appeals in Boston will hear oral arguments from Bulger's lawyers, who are trying to overturn his racketeering convictions. Bulger is serving a life sentence in Florida and won't be present for Monday's proceedings.

Bulger's attorneys contend his right to a fair trial was violated when a judge barred him from telling the jury about his claim that a federal prosecutor promised him immunity. Judge Denise Casper found that Bulger offered no hard evidence of an immunity deal.

Prosecutors say the evidence overwhelmingly showed Bulger's guilt and he shouldn't get a new trial.

Bulger, 85, was convicted in 2014 of participating in 11 murders in the 1970s and '80s. He was one of the FBI's most wanted fugitives until his capture in Santa Monica, California, in 2011.

Bulger headed Boston's Irish mob and was an FBI informant against the rival New England mafia. His case became an embarrassment for the FBI when it was revealed that a corrupt Boston agent took bribes from him and shielded him from prosecution.

Bulger cited Casper's ruling when he decided not to testify in his own defense. He told the judge he felt he'd been "choked off from having an opportunity to give an adequate defense."

"And my thing is, as far as I'm concerned, I didn't get a fair trial, and this is a sham," Bulger said.

In his appeal, Bulger's lawyers argue that if he had been allowed to testify about his immunity claim in his own words, the jury would have had the chance to weight his credibility against the credibility of prosecution witnesses.