Ex turpi causa non oritur actio

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Ex turpi causa non oritur actio (Latin "action does not arise from a dishonourable cause") 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.^[1] The corresponding Ex turpe causa non oritur damnum, "From a dishonourable cause, no damage arises" is a similar construction. Particularly relevant in the law of contract, tort and trusts,^[2] 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.^[3]