It has been observed justly that few legal doctrines have given rise to so vigorous and sustained a conflict of judicial attitudes as the concept of strict penal responsibility. The theory of mens rea which preceded the origins of the common law, is ingrained in English criminal jurisprudence. An English court has asserted that ‘It is contrary to the whole established law of England (unless the legislation on the subject has clearly enacted it) to say that a person can be guilty of a crime in England without a wrongful intent’. In circumstances involving technical guilt bereft of moral blame English judges have looked askance at invocation of the criminal process. The American Law Institute has recently declared that ‘No principle is more broadly accepted than that the criminal law, involving as it does both punishment and condemnation, should be concerned with conduct that is morally reprehensible or culpable’.

In recent years various developments in the system of trial by jury in England and Wales have given rise to comment and concern. One such development was the abolition by s. 13 of the Criminal Justice Act 1967 of the rule, said to have existed for over 600 years, that a jury must be unanimous in order to reach a verdict. These provisions are now contained in s. 17 of the Juries Act 1974 which allows for majority verdicts where there are no more than two dissentient voices to be returned under certain circumstances. The change in the unanimity rule has been criticised as striking at the root of the principle of proof of guilt beyond reasonable doubt and has been interpreted by some as being the first step on the slippery slope to jury verdicts by simple majority, a development which would do even more to undermine the principle of proof beyond reasonable doubt and might also lead to the complete abolition of trial by jury.

The English jury has recently been undergoing various alterations. These changes have their roots in assumptions, often not clearly identified, about the nature and purpose of the jury within the criminal justice system. Once the purpose and ideals of the jury system are identified, and there may be arguments about what they are, it becomes apparent that there may be a conflict about how they should be put into practice. The state and its agencies may take one view whilst others may differ. An example of one such conflict is the controversy over the newly discovered practice of ‘jury vetting’.

The maxim ‘ignorance of the law is no excuse” has much to answer for. Defendants arguing that they did not know or misunderstood the law have been told that their ignorance or mistake made no difference to their liability. The institutional writers have laid down as much. The courts have repeatedly emphasised it.

However, it is here submitted that this blanket approach, characterised by the very existence of such a general maxim, is misconceived. No such general principle exists, nor should it. Although the judges have spoken in general terms, their remarks really depend on the context of the particular offences in question, where no knowledge of the law has been necessary, and liability has been (in this respect at least) ‘strict’.

In Torquay Hotel Co Ltd v Cousins Lord Denning MR asserted: ‘I have always understood that if one person deliberately interferes with the trade or business of another, and does so by unlawful means … then he is acting unlawfully, even though he does not procure or induce any actual breach of contract’. Although during the parliamentary debate over what became the Employment Act 1980, Lord Hailsham stated that no such tort existed, Lord Wedderburn replied that ‘a student of today must be affected by legal myopia if he did not understand the existence of this tort’. The purpose of this article is to examine the existence and scope of this tort – which I shall refer to as unlawful interference with trade – to place it in the context of the known economic torts, to discover its common law background and to outline its present and possible future role in commercial and industrial law.