A federal judge has declined to throw out a lawsuit accusing Chicago’s Independent Police Review Authority of retaliating against an investigator for testifying in a coworker’s criminal trial.In a written opinion this week, U.S. District Judge John Robert Blakey did not rule on the merits of Martrice Campbell’s allegations that she was falsely accused of perjury and then fired by a supervisor angered by the coworker’s acquittal.But Blakey held the allegations were enough to state a claim against the …