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.^[1]

The typical SLAPP 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. A SLAPP may also intimidate others from participating in the debate. A SLAPP is often preceded by a legal threat. The difficulty is 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.

SLAPPs take various forms. The most common used to be a civil suit for defamation, which in the English common law tradition was atort. The common law of libel dates to the early 17th century and (unusual in English law) is reverse onus, meaning, once someone alleges a statement is libelous, the burden was on the defendant to prove that it is not. The Defamation Act 2013 removed most of the uses of defamation as a SLAPP in the United Kingdom by requiring the proof of special damage. Various abusive uses of this law including political libel (criticism of the political actions or views of others) have ceased to exist in most places, but persist in some jurisdictions (notably British Columbia and Ontario) where political views can be held as defamatory. A common feature of SLAPP suits is forum shopping, wherein plaintiffs find courts that are more favourable towards the claims to be brought than the court in which the defendant (or sometimes plaintiffs) live.