The constitution creates a federalist system, in which States retain general police power not superseded or limited by the Constitution or federal law. Under President George W. Bush, the United States adopted two seemingly conflicting positions. At the federal level, President Bush has rejected the Kyoto Protocol and declined to develop any material foreign or domestic policies to limit greenhouse gas (GHG) emissions. At the state level, many states adopted a wide range of policies, statutes and regulations addressing GHG emissions. Critics of these policy initiatives question whether States possess the constitutional authority to address global warming, citing the doctrines of preemption, the dormant commerce clause, and the federal foreign affairs power. However, analysis of the Supreme Court’s understanding of these doctrines reveals that none of them bars a State from addressing GHG emissions. In short, States have the power and authority to think globally, but act locally.