In recent times, the English courts have treated claims for infringement of foreign intellectual property rights, and claims for breach of foreign copyright in particular, as if they had a magical quality which prevented them from being scrutinised. In the nature of Kryptonite, their very presence had the remarkable effect of sapping judicial powers. The source of this phenomenon in the Commonwealth can be traced to the decision of the High Court of Australia in Potter v Broken Hill Pty Co Ltd,1 although it was only in the latter part of the twentieth century that its influence was felt in England.2 Some judges found ways to resist,3 but in Lucasfilm Ltd v Ainsworth 4 the Court of Appeal found itself powerless to determine a claim for infringement of a foreign (United States) copyright and concluded that it was irrelevant that no issue as to the validity or subsistence of copyright arose for decision in that case. In its decision delivered last summer,5 the Supreme Court took a more robust line, allowing the claimant’s appeal on this point, while upholding the lower courts’ rejection of a claim based on alleged infringements of UK copyright legislation.