A Strategic Lawsuit Against Public Participation ("SLAPP") is a form of litigation filed by a large organization or in some cases an individual plaintiff, to intimidate and silence a less powerful critic by so severely burdening them with the cost of a legal defense that they abandon their criticism.

California enacted Code of Civil Procedure § 425.16 in 1992, a statute intended to prevent the misuse of litigation in SLAPP suits. It provides for a special motion which a defendant can file at the outset of a lawsuit to strike a complaint where the complaint arises from conduct that falls within the rights of petition or free speech...It also applies to speech in a public forum about an issue of public interest and to any other petition or speech conduct about an issue of public interest.

The filing of an anti-SLAPP motion prevents the plaintiff from amending the complaint and stays all discovery. If the special motion is denied, the filing of an appeal immediately stays the trial court proceedings as to each challenged cause of action.