Center for Biological Diversity v. National Highway Traffic Safety Administration

NHTSA (defendant) issued fuel-economy standards for light trucks and SUVs after preparing only an Environmental Assessment, rather than a full Environmental Impact Statement, concluding the standards would have no significant environmental impact through a minimal cost-benefit analysis; the agency conceded the standards would merely slow the rate of growth in carbon emissions rather than actually reducing them, but declined to quantify the value of emissions reductions or analyze cumulative climate-change effects. Environmental groups and multiple states (plaintiffs) petitioned for review, and NHTSA argued its Environmental Assessment was adequate under NEPA.