Pseudolaw (from the Greek "ψευδής" (pseudo); "false") consists of pseudolegal statements, beliefs, or practices that are claimed to be based on accepted law or legal doctrine, but which deviate significantly from most conventional understandings of law and jurisprudence, or which originate from non-existent statutes or legal principles the advocate or adherent incorrectly believes exist. Canadian legal scholar Donald J. Netolitzky defined pseudolaw as "a collection of legal-sounding but false rules that purport to be law", a definition that distinguishes pseudolaw from arguments that fail to conform to existing laws such as novel arguments or an ignorance of precedent in case law. Pseudolegal arguments are sometimes referred to as "legalistic gibberish". Netolitzky has compared pseudolaw to "a form of legal quackery or snake oil"; lawyer Colin McRoberts has called it "law in a Post-Truth Era". The term Organized Pseudolegal Commercial Arguments (OPCA) was coined in a 2012 Canadian court decision as an umbrella term for pseudolegal tactics and arguments, and has since been used by lawyers and legal scholars in Commonwealth countries.
Pseudolaw has distinct features; it often purports to base itself on "common law", though its interpretations thereof has not found any purchase in any contemporary or historical understandings of common law. It may be used by people who engage in vexatious or frivolous litigation. The more extreme examples of pseudolegal tactics have been classified as paper terrorism - sheer harassment rather than a genuine attempt to argue one's legal position. Pseudolitigation may also waste considerable judicial time.
Litigants who use pseudolaw generally dispense with real legal counsel. They frequently rely on techniques and arguments promoted and sold – sometimes as "kits" – by amateur legal theorists, who are commonly called "gurus" by courts, scholars and media. Pseudolegal theories and schemes are disseminated and advertised through websites, isolated documents, texts of varying length, seminars, radio broadcasts, instructional DVDs and, above all, YouTube videos.