States should be allowed to restrict greenhouse-gas emissions from cars, and Big Auto should just deal, a federal judge ruled today. Right now, the only real way to curb the emissions is to improve gas mileage; when Vermont decided to adopt California’s strict emissions rules, automakers sued, claiming that the state was illegally regulating fuel economy — and that making cleaner cars was unattainable and unsafe, to boot. U.S. District Judge William Sessions didn’t see it that way: “The court does not find convincing the claims that consumers will be deprived of their choice of vehicles, or that manufacturers will be forced to restrict or abandon their product lines,” he wrote. “History suggests that the ingenuity of the industry, once put in gear, responds admirably to most technological challenges.” The ruling, while significant, doesn’t mean the fight is over: Automakers have a similar suit awaiting verdict in California, and the U.S. EPA also has yet to rule on whether California can implement its stricter standards.