A strategic lawsuit against public participation (SLAPP) is a lawsuit that is intended to censor, intimidate, and silence critics by burdening them with the cost of a legal defense until they abandon their criticism or opposition. Such lawsuits have been made illegal in many jurisdictions on the grounds that they impede freedom of speech.
In the typical SLAPP, the plaintiff does not normally expect to win the lawsuit. The plaintiff's goals are accomplished if the defendant succumbs to fear, intimidation, mounting legal costs, or simple exhaustion and abandons the criticism. In some cases, repeated frivolous litigation against a defendant may raise the cost of directors and officers liability insurance for that party, interfering with an organization's ability to operate. A SLAPP may also intimidate others from participating in the debate. A SLAPP is often preceded by a legal threat.
There is a difficulty in that plaintiffs do not present themselves to the court admitting that their intent is to censor, intimidate, or silence their critics. Hence, the difficulty in drafting SLAPP legislation, and in applying it, is to craft an approach which affords an early termination to invalid abusive suits, without denying a legitimate day in court to valid good faith claims. Thus, anti-SLAPP laws target tactics used by SLAPP plaintiffs. Common anti-SLAPP laws include measures such as penalties for plaintiffs who file lawsuits ruled frivolous and special procedures where a defendant may ask a judge to consider that a lawsuit is a SLAPP (and usually subsequently dismiss the suit).
Anti-SLAPP laws occasionally come under criticism from those who believe that there should not be barriers to the right to petition for those who sincerely believe they have been wronged, regardless of ulterior motives. Nonetheless, anti-SLAPP laws are generally considered to have a favorable effect, and many lawyers have fought to enact stronger laws protecting against SLAPPs.