Judge William Sessions didn't buy the argument of GM and DaimlerChrysler, and instead upheld the Vermont law. While the standards are tighter than the Federal regulations, Sessions was not convinced that they pre-empt the nationwide requirements. It does appear like a thorny States Rights question, and if more states than the current dozen or so adopt California emissions guidelines, it will continue to cause consternation. It does make the federal regs look useless when states are passing requirements that are more rigorous. It also creates extra cost for automakers, as they've either got to make all of their cars compliant, or sell "Federal" and "California" versions of the same car. The decision will be appealed by the automakers, and we expect this issue to have legs – this is not the last we'll hear of this debate.
[Source: Automotive News – sub req.]