The govt decided to end (the next year) a statutory scheme under which only registered persons could be dock workers. Employers refused to give guarantees that the dock workers would be treated no less favourably, and so announced a strike. This was in breach of a statutory duty to work a reasonable number of hours, and P sought an injunction against the union, D, stopping it from calling the strike. This was on the grounds that that it is tortious intentionally to cause harm to business by unlawful (here, in breach of the statute) means. CA accepted this argument and awarded the injunction.
Neill LJ: the employers had an arguable case that unlawful means can include inducement of breaches of duty which are not actionable by the plaintiff against the party in breach, even though he saw "great force" in the union's argument to the contrary. NB, the claim succeeded because it was based on the tort of intentionally causing harm to P’s business in breach of statutory duty (i.e. by unlawful means). Breach of statutory duty alone wouldn’t be enough, as this is not generally actionable by individuals (see tort notes).
House of Lords Decision: Overturned CA on the narrow point that the statutory duty had been misconstrued, but didn’t deny the reasoning of the CA with regard to liability for tortious wrong of intentionally causing harm to P’s business by unlawful means.