Carbon dioxide must be regulated by the federal government unless it can provide a scientific reason not to, the Supreme Court ruled Monday. The 5-4 decision, which ordered the EPA to consider CO2 an "air pollutant" as defined by the Clean Air Act, was a blow to the Bush administration's policy of refusing to regulate factory and automobile emissions.
The legal issue of "standing," rather than the fate of the environment, was the focus of the case, with Chief Justice John Roberts arguing that the group that filed the lawsuit wasn't directly injured by the EPA. But the majority was convinced that the plaintiff, Massachusetts, is directly threatened by rising sea levels increased regulation could prevent. (Read more carbon dioxide stories.)