The court granted a motion by defense lawyers, The Boston Globe reported. The opinion, written by retired U.S. Supreme Court Justice David Souter sitting as a circuit judge, pointed to U.S. District Judge Richard Stearn's history with the U.S. Attorney's Office. Stearns was an assistant U.S. attorney while Bulger was serving as an FBI informant.
"With great respect for the trial judge, we nonetheless grant the petition, because it is clear that a reasonable person would question the capacity for impartiality of any judicial officer with the judge's particular background in the federal prosecutorial apparatus in Boston during the period covered by the accusations,'' Souter said.
Bulger said that Jeremiah O'Sullivan, an assistant U.S. attorney in the 1980s, gave him complete immunity from prosecution for any crimes, including mruder. Bulger said the agreement with O'Sullivan, who died in 2009, was verbal.
After 16 years on the run, Bulger and his girlfriend, Catherine Greig, were arrested in Santa Monica, Calif., in 2011. He faces a long list of charges, including 19 killings.
Bulger is scheduled to go on trial in June.