Although the United States is not a party to the Kyoto Protocol, a multitude of alternative domestic approaches to combat climate change have emerged at all levels of government. The article takes as given that climate change is a serious environmental problem that requires a legal response. Building on conference presentations at a USF symposium in March 2007, this article evaluates the most significant existing federal and state measures, including federal voluntary measures, California's vehicle emissions standards and global warming legislation, and the Regional Greenhouse Gas Initiative. The article also addresses three litigation initiatives: Massachusetts v. EPA, Friends of the Earth v. Mosbacher, and the states' public nuisance actions against electric utilities and auto manufacturers.

The article not only highlights the key features of federal, state, and litigation initiatives; it also addresses their respective roles. In responding to climate change, the nation must confront profound institutional questions about the relationship between federal and state regulation, as well as the relationship between democratic processes and the courts. In the article, I conclude that each of our legal institutions, including the federal government, the states, and the courts, has a role to play. Letting them play their respective roles increases the likelihood that our legal institutions will respond effectively to the fundamental challenge posed by global climate change.