ex turpi causa non oritur actio
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ex turpi causa non oritur actio‘an action will not arise from a disgraceful basis’. In the modern law the disgraceful element is usually considered in terms of illegality or immorality. The doctrine, once confined to contract, often appears in other areas of the law, in particular tort. However, as the modern law has created many offences and crimes that involve little or no turpitude, the maxim is seldom applied as a strict bar to action.
Collins Dictionary of Law © W.J. Stewart, 2006