From Wikipedia, the free encyclopedia

In civil law, especially contract law, ex turpi causa non oritur actio is the doctrine that an action may not be founded on illegality. (The term is Latin, and means roughly "a dishonorable cause does not give rise to an action.") In US courts, this rule is more commonly known as the equitable principle of unclean hands. If the doctrine applies, the plaintiff is unable to pursue his cause of action.

The doctrine's principal application is to be found in the law of contract, and indeed some commentators confine its effect to contract alone (see: Winfield & Jolowicz on Tort, 15th edition, p866).

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 [1954] AC 403, Lord Asquith said "If two burglars, A and B, agree to open a safe by means of explosives, and A so negligently handles the explosive charge as to injure B, B might find some difficulty in maintaining an action against A."

For example, in Revill v Newberry [1996] 1 All ER 291, 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 defendants successfully raised the defence of ex turpi to avoid the claim. However, the Court of Appeal allowed the plaintiff's appeal, holding that the defendant was negligent to have shot blindly at body height, without shouting a warning or shooting a warning shot into the air, and that the response was out of all proportion to the threat.

The precise scope of the doctrine is not certain. In some cases, it seems that the illegality prevents a duty of care arising in the first place. For example, in Aston v Turner [1981] QB 137, the defendant crashed a car in the course of getting away from the scene of a burglary, injuring the plaintiff. Ewbank J held that the court may not recognise a duty of care in such cases as a matter of public policy. Similarly, in Pitts v Hunt [1990] 3 All ER 344, the Court of Appeal rationalised this approach, saying that it was impossible to decide the appropriate standard of care in cases where the parties were involved in illegality. In other cases, the courts view ex turpi as a defence where otherwise a claim would lie, again on grounds of public policy. In Tinsley v Milligan [1992] Ch 310, Nicholls LJ (as he then was) in the Court of Appeal spoke of the court having to "weigh or balance the adverse consequences of granting relief against the adverse consequences of refusing relief". The plaintiff was ultimately successful in Tinsley v Milligan in the House of Lords, which allowed the claim on the grounds that the plaintiff did not need to rely on the illegality.

• Acts of the claimant
• Contributory negligence
• Volenti non fit injuria