In the tricky legal world of "preemption" -- the principle that federal law "preempts," or trumps, state law -- two recent Supreme Court decisions bode well for ongoing, seemingly unrelated global warming litigation. The first of these decisions, Altria Group, Inc et al. v. Good et al., concerned a class-action lawsuit brought by smokers in Maine, who claimed the manufacturers of "light" cigarettes used deceptive practices by promoting their product as having fewer health risks than normal cigarettes. The cigarette makers, by contrast, argued that they were immune from state fraud claims if they have met federal cigarette labeling law. …