Editors' Summary

In December 2007, EPA denied a request submitted by California pursuant to §209 of the CAA. That request for a waiver from federal preemption, if granted, would have allowed California to set its own motor vehicle emission standards for greenhouse gases (GHGs). This waiver request is unique; it marks the first waiver request submitted by California to regulate GHGs in order to mitigate climate change. Its subsequent denial is significant for, primarily, two reasons. First, this was the first waiver request ever flatly denied by EPA. Second, this was the first post-Massachusetts v. U.S. Environmental Protection Agency decision by EPA to reject its clear authority to regulate GHGs under the CAA.