(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, 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. Illegality in English Law Development In the early case of Holman v Johnson Lord Mansfield CJ set out the rationale for the illegality doctrine. Tort In the law of tort, the principle would prevent a criminal from bringing a claim against (for example) a fellow criminal. In National Coal Board v England, Lord Asquith said, In Hewison v Meridian Shipping Services Pte Ltd, an employee who had obtained his position by concealing his epilepsy was held not to be entitled to claim compensation for future loss of earnings as a result of his employer's negligence, since his deception (resulting in a pecuniary advantage contrary to the Theft Act 1968) would prevent him from obtaining similar employment in future. It is not absolute in effect. For example, in Revill v Newbery an elderly allotment holder was sleeping in his shed with a shotgun, to deter burglars. On hearing the plaintiff trying to break in, he shot his gun through a hole in the shed, injuring the plaintiff. At first instance, the judge awarded damages on the basis that the defendant had used violence in excess of the reasonable limits allowed by lawful self-defence and was negligent to the standard of care expected of a reasonable man who found himself in such a situation. On appeal the defendant raised the defence of , but the Court of Appeal held that while public interest required that someone should not benefit from his illegal conduct, different considerations applied in cases arising in tort as opposed to those in a property or contract context. Old common law authorities and the Law Commission report (Liability for Damage or Injury to Trespassers) acknowledged the existence of some duty towards trespassers and the defendant could not rely on the doctrine to relieve himself