Langton v Secretary of State for Environment, Food and Rural Affairs concerns judicial review proceedings against the Secretary of State in respect of guidance relating to the culling of badgers. The claimant alleged—inter alia—that the policy was unlawful as it was based on scant scientific evidence. The core of the case is this: where a novel approach to solving a problem is suggested, is it lawful for a public authority to rely on scientific evidence which cannot, by definition, be based on data from past experience? Although the question is raised in the specific context of the environmentally-controversial badger cull, the wider issue of novelty and administrative decision-making in an environmental context can cut both ways. A court’s assessment as to how public authorities may proceed in such cases will be critical both where the environment is at risk, and where measures are taken with a view to protecting the environment. The Court of Appeal’s comments regarding the very nature of scientific certainty are significant (a) for their departure from the general tenor of the approach of the Court of Justice of the European Union (CJEU), and (b) for their recognition that scientific uncertainty is an intractable problem and that we must, therefore, develop decision-making strategies which acknowledge, rather than attempt to mask, this reality. This note will consider the background to and decision in the case, before addressing these wider issues.