During this lecture, professor Chris Hilson (University of Reading) will be speaking about his research on the Dutch nitrogen crisis and the extent to which the ‘legal stock’ shaped the environmental movement’s framing of nitrogen as a biodiversity problem (rather than a climate or a pollution one). His paper explores the Dutch nitrogen crisis through a legal mobilisation lens. It employs two key conceptual elements from that literature – framing, and legal opportunity structure (LOS). The paper analyses the extent to which the ‘legal stock’ within LOS in the form of the EU Habitats Directive shaped the environmental movement’s framing of nitrogen as a biodiversity problem (rather than a climate or a pollution one). It further discusses the idea of ‘stealthy’ framing, where the legal stock used does not reflect the movement’s real motivation, but argues that the nitrogen litigation here is not an example of that.