Ex turpi causa non oritur actio

Ex turpi causa non oritur actio (Latin "from a dishonorable cause an action does not arise") is a legal doctrine which states that a plaintiff will be unable to pursue legal relief and damages if it arises in connection with their own tortious act. Particularly relevant in the law of contract, tort and trusts, ex turpi causa is also known as the illegality defence, since a defendant may plead that even though, for instance, he broke a contract, conducted himself negligently or broke an equitable duty, nevertheless a claimant by reason of his own illegality cannot sue. The UK Supreme Court provided a thorough reconsideration of the doctrine in 2016 in Patel v Mirza.