A divided court decreed that the personnel code requires that employees complain to their employers if they disclose wrongdoing and then are demoted or harassed.
Justices Philip Rarick and Charles Freeman dissented. Rarick says the action will dissuade whistleblowers from speaking up.
State Police employee Linette Metzger won $138,000 in damages from a federal jury in 2001 because she was transferred and lost privileges after complaining that other employees were regularly absent from work without permission, but a federal appeals court asked the Illinois justices whether the personnel code allowed private lawsuits.
Justice Thomas Kilbride's opinion said that the administrative procedure, with fines and criminal penalties, sufficed.