Despite Lord Woolfe’s attempt to eradicate Latin phrases from lawyers’ language, the maxim ‘ex tupri causa’ lives on. In its full version ‘Ex turpi causa non oritur’ literally means ‘from a dishonourable cause an action does not arise’. In other words, a claimant may not pursue a legal remedy if it arises out of his own illegal act. 

The leading case of Les Laboratoires Servier and Another v Apotex Inc and Others (2012) raised the question whether a patentee who had obtained an interim injunction from the Patents Court to restrain infringement of a European patent (UK) which was subsequently held invalid should compensate the defendant for losses sustained as a result of being prevented by the injunction from selling goods manufactured by the defendant in infringement of a valid foreign patent owned by the same group of companies. In that case, the court decided that the money should not be repaid, invoking ex turpi causa, on the basis that the claim would have necessitated an illegal act to have manifested in the first place. 

The Les Laboratoires case applied a strict interpretation of ex turpi causa and, where it existed, there was no claim. 

How does this apply to trespassers or where a claimant steals a motorcycle and gets hit by a car emerging from a side road? The application of the principle in personal injuries is blurred. In the case of Joyce v O’Brien and Another (2013), two joyriders had stolen a motorcycle which then collided with another vehicle. The court decided that a claim by the injured passenger joyrider could not be made against his accomplice on the basis that they were both part of a joint enterprise and ex turpi causa would apply. However, it did not prevent the injured passenger from claiming against the other vehicle on account of their negligence, although the court did reduce the amount of compensation on account of contributory negligence for the passenger’s involvement in the joyride. 

The Penningtons Manches personal injury team has successfully defended a case where ex turpi causa was pleaded in a case where a prisoner fought with prison custody officers to avoid being put into a transportation cell after being sentenced. It took a number of guards to subdue him and he sustained injury as a result of the fight. Ex turpi causa was pleaded in the defence on the basis that his injuries arose out of his illegal act of attacking the prison staff.