A Minnesota Supreme Court ruling this week put limits on when a person can claim prosecutorial immunity.

The case involved Catharine Morton-Peters, chief investigator for the Medicaid Fraud Control Unit of the state attorney general’s office. After she obtained a search warrant for Affiliated Counseling Center in Fridley, police took files from the center. Marcia Stresemann, the center’s owner, sued when some of the files weren’t returned.

Morton-Peters moved to dismiss the suit on the grounds of prosecutorial immunity, arguing that immunity should extend to nonprosecutors who are involved in the investigation stage of a case.

In its decision, the court stated that “prosecutorial immunity does not extend to an investigator whose conduct is not intimately involved with the initiation and maintenance of criminal charges.” The Minnesota Court of Appeals had previously granted immunity to Morton-Peters, so its decision was reversed and remanded.

The American Civil Liberties Union of Minnesota argued in its brief that during the investigation stage of a case, no one should have absolute immunity from monetary damages for misconduct. “This is a good decision that ensures individuals whose rights were violated by a prosecutor or an investigator are better protected under the law,” said Charles Samuelson, executive director of ACLU-MN.