On April 29, the Ninth Circuit (federal) Court of Appeals issued an important ruling on national pesticide regulation, directed at the controversial organophosphate insecticide chlorpyrifos. The order directs the Environmental Protection Agency (EPA) to act within 60 days to either announce an enforceable safe exposure level for use, or to ban the pesticide. The case, League of United Latin American Citizens (LULAC) v. Regan, interprets and applies the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), and related authority under the Federal Food, Drug, and Cosmetic Act (FFDCA). This decision is the latest step in controversies dating to 2006, involving years of EPA inaction spanning the Obama and Trump administrations.