The Canadian case Monsanto v Schmeiser has attracted considerable attention around the world. The Schmeiser litigation has, in particular, raised fears about the scope of patent liability in cases of genetic drift. Patent infringement is not dependent upon proof of knowledge on the part of the defendant. There is therefore the possibility that farmers who, through no fault of their own, end up with patented varieties of genetically-modified (GM) plants or animals on their land will be held liable for patent infringement in certain circumstances. Schmeiser has come to be representative of these concerns, because although it was held that the defendant was aware of the presence of the GM variety, at neither first instance nor on appeal to the Federal Court of Appeal was this finding treated as directly relevant to the question of infringement. In contrast, in its decision the Supreme Court of Canada showed greater awareness of the problem of innocent infringement. Most significantly, the majority construed elements of the test for patent infringement in such a way as to make it less likely that an entirely innocent defendant would be held to infringe. Unfortunately, however, the Court’s approach also leaves a number of important questions unanswered and it is unclear what impact the decision will have in other jurisdictions. A further complicating factor is that although the defendant was found to have infringed, Monsanto was not awarded a financial remedy and had to pay its own costs. This has led some commentators to present the decision as a pyrrhic victory for Monsanto. This interpretation should be treated with caution, however, since it may distract attention from Schmeiser’s potential significance.