A Strategic Lawsuit Against Public Participation (SLAPP) is a civil complaint or counterclaim that attempts to silence criticism by alleging that an exercise of free speech was defamatory, conspiratorial or otherwise injurious. SLAPPs are often brought by corporations or government officials or agents who were criticized in connection with public issues.
The purpose of SLAPPs is usually to chill public criticism. They are to scare people away from speaking out.
To prevent this effect, California and some other states have passed anti-SLAPP statutes that give victims of SLAPP lawsuits special rights, such as the ability to recover attorneys' fees spent in defending against a SLAPP claim.