The False Claims Act has proven to be one of the most effective tools in fighting Medicare fraud, defense contractor fraud and other types of fraud perpetrated against the federal government. The False Claims Act also stipulates that whistleblowers get a share of the amount the government recovers as a result of their lawsuits. Since the False Claims Act was amended, the government has recovered billions of dollars as a result of qui tam lawsuits.
Many states have their own versions of the False Claims Act.
Under those false claims acts, whistleblowers can recover money against defendants who commit fraud against state and local governments. 2000 Phillips and Cohen. This site discusses how the False Claims Act works.