The EPA and automakers have won an important appeal in federal court that will keep the agency from enforcing carbon dioxide limits on passenger cars, with two of three judges sitting on the District of Columbia Circuit of Appeals siding on the side of no regulatory action. Various states and environmental groups filed the original lawsuit in an effort to force the EPA to address the issue, while the agency argued that it does not have congressional authority to do so. Other states - those with significant automotive industry presence - joined the EPA's side in the case. Our take? There's sketchy evidence supporting the claim that CO2 emissions from autos causes global warming, but on the other hand, common sense says that releasing millions of years of stored carbon in less than a century will have an impact of some sort. Since there's no practical way to trap CO2, any limit on its emission will be a de facto increase in the federal fuel economy standard - and we know how well that concept has gone over with Congress, automakers, and car buyers in recent times. There'll be more to follow on this issue, for sure.