A qui tam action. A statutory action that allows a private person to sue for a penalty on behalf of the government. Any penalty awarded is divided between the government and the relator. For example, a private person may bring suit against one who is filing false claims for payment from the US government under the False Claims Act. That private person can sue as a relator, and the plaintiff's name will be listed as "U.S. ex rel. Private Party" in the caption of the case.

A suit upon information. A state attorney general or the federal Department of Justice may bring a suit at the instigation of a private person who needs the state to enforce the rights of himself and the public.