The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved for the States respectively, or to the people.
10th Amendment to the United States Constitution
Liberals and environmentalists usually are not great fans of this Amendment--having, after all, appointed Judges over the last 75 years who have decimated the force of the Amendment until it is but a vestige of its intended prominence--but occasionally even the Left finds it helpful that the 10th Amendment has not entirely lapsed into desuetude. (Per Wikipedia, "desuetude (from the French word désuet, outdated) is a doctrine that causes statutes, similar legislation or legal principles to lapse and become unenforceable by a long habit of non-enforcement or lapse of time. It is what happens to laws that are not repealed when they become obsolete. It is the Legal doctrine that long and continued non-use of a law renders it invalid, at least in the sense that courts will no longer tolerate punishing its transgressors.") (Note: legal links in Wikipedia quote won't work from here; go to the Wikipedia link and they will work from there).
This past Wednesday, September 12, 2007, a Vermont federal Judge--to the delight of Liberals/environmentalists everywhere-- ruled in Green Mountain Plymouth Dodge Jeep v. Crombie that the State of Vermont retains the right to adopt rules forcing automobile makers to require carbon dioxide emissions from cars be reduced by as much as 30 percent over the next 10 years. The judge rejected the auto industry's argument that federal laws and EPA regulations preempt this field.
Normally Big Government types such as California Governor Arnold Schwarzenegger and California Attorney General Jerry Brown could barely contain their joy, especially since the ruling gave them the opportunity to burnish their environmental credentials by bashing the Bush Administration yet again. Brown threatened, as has the Governor in the past, to sue federal EPA if the agency does not grant California waivers to enforce that State's own emissions-regulation law.
Forgive me for being a skeptic-- but I doubt Jerry Brown is now a States' Rights supporter. Somehow methinks his enthusiasm will fade when the subject turns to some liberal cause that is best promoted by forgetting the 10th Amendment was, in fact, ever adopted.