The new judge presiding over the upcoming trial of James “Whitey” Bulger has given his lawyers until March 28 to file another brief on the gangster’s immunity claim. According to the docket on the case in federal court in Boston, Judge Denise J. Casper has also scheduled a status conference for March 26. Bulger, 83, is slated to go to trial in June on a sweeping indictment charging him with 19 murders. He is seeking to have the jury weigh his claim at trial that a former top federal prosecutor granted him immunity to commit crimes, including murder. Prosecutors have rejected that claim and contend that it should not be presented to the jury.