An operative fact is a fact or event that has direct legal effect in itself, giving rise to, altering or extinguishing legal rights or obligations, rather than merely providing evidence of them. In practice, it is a fact that the law treats as constitutive of a legal relationship or consequence, for example: making a contractual offer and acceptance, serving a statutory notice, publishing an allegedly defamatory statement, or committing a tortious or criminal act.The expression “operative fact” is largely descriptive and doctrinal rather than a defined statutory term in the UK or Ireland. It is used in litigation, legal drafting and legal analysis to distinguish between: (i) facts that create or change legal rights (operative facts) and (ii) evidential facts used to prove those operative facts.Identifying operative facts is central to pleading a cause of action, framing issues for trial, advising on limitation, and assessing remedies. Usage is broadly consistent across England and Wales, Scotland, Northern Ireland and Ireland, including in contract law, tort/delict, property law and public law, although particular operative facts will depend on the substantive legal rules of each jurisdiction.