[JURIST] The US Court of Appeals for the Ninth Circuit [official website] threw out planned federal fuel economy standards [NHTSA materials] for light trucks and SUVs Thursday, ruling that the National Highway Traffic Safety Administration (NHTSA) [official website] did not adequately consider the environmental impact of the proposed standards. The ruling came in a lawsuit [JURIST report] brought by several states and environmental groups, which argued that the NHTSA ignored the effects of carbon dioxide emissions and certain SUV and truck classes when calculating the new fuel emissions standards. The new standards were due to go into effect next year and require an increase in the average fuel economy for all US passenger trucks from 22.2 miles per gallon to 23.5 miles per gallon by 2010.

In its opinion [PDF text], the Ninth Circuit wrote:

We hold that the Final Rule is arbitrary and capricious, contrary to the [Energy Policy and Conservation Act] in its failure to monetize the value of carbon emissions, failure to set a backstop, failure to close the SUV loophole, and failure to set fuel economy standards for all vehicles in the 8,500 to 10,000 gross vehicle weight rating ("GVWR") class. We also hold that the Environmental Assessment was inadequate and that Petitioners have raised a substantial question as to whether the Final Rule may have a significant impact on the environment. Therefore, we remand to NHTSA to promulgate new standards as expeditiously as possible and to prepare a full Environmental Impact Statement.

AP has more.