“to allow recovery in these cases would be to allow recovery for what is illegal. It would put the courts in the position of saying that the same conduct is both legal, in the sense of being capable of rectification by the court, and illegal. It would, in short, introduce an inconsistency in the law. It is particularly important in this context that we bear in mind that the law must aspire to be a unified institution, the parts of which - contract, tort, the criminal law - must be in essential harmony. For the courts to punish conduct with the one hand while rewarding it with the other, would be to ‘create an intolerable fissure in the law’s conceptually seamless web’ ... We thus see that the concern, put at its most fundamental, is with the integrity of the legal system.” 25. The ex turpi causa principle is concerned with claims founded on acts which are contrary to the public law of the state and engage the public interest. The paradigm case is, as I have said, a criminal act. In addition, it is concerned with a limited category of acts which, while not necessarily criminal, can conveniently be described as “quasi-criminal” because they engage the public interest in the same way. Leaving aside the rather special case of contracts prohibited by law, which can give rise to no enforceable rights, this additional category of non-criminal acts giving rise to the defence includes cases of dishonesty or corruption, which have always been regarded as engaging the public interest even in the context of purely civil disputes; some anomalous categories of misconduct, such as prostitution, which without being criminal are contrary to public policy and involve criminal liability on the part of secondary parties; and the infringement of statutory rules enacted for the protection of the public interest and attracting civil sanctions of a penal character, such as the competition law considered by Flaux J in Safeway Stores Ltd. v. Twigger [2010] Bus LR 974”
“if detailed semantic and syntactical analysis of words in a commercial contract is going to lead to a conclusion which flouts business commonsense, it must be made to yield to business commonsense.”