It is not for his sake, however, that the objection is ever allowed; but it is founded in general principles of policy, which the defendant has the advantage of, contrary to the real justice, as between him and the plaintiff, by accident, if I may say so.
If, from the plaintiff's own standing or otherwise, the cause of action appears to arise ex turpi causa ["from an immoral cause"], or the transgression of a positive law of this country, there the court says he has no right to be assisted.
In National Coal Board v England,[5] 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 for negligence against A.In Hewison v Meridian Shipping Services Pte Ltd,[6] 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.
For example, in Ashton v Turner[8] the defendant injured the plaintiff by crashing the car they sat in together in the course of fleeing the scene of a burglary they had committed together.
Further, in Pitts v Hunt[9] 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.
Here contractual remedies cannot be enforced by a court on a defendant if it is manifest that the subject matter of the contract is either directly or by implication, contrary to public policy or in contradiction with any existing law or custom.
In 2016 the UK Supreme Court provided a major reconsideration of this doctrine, in Patel v Mirza,[3] overruling the test in Tinsley v Milligan and replacing it with a new set of principles.