Commentary: Landmark U.S. Supreme Court decision puts U.S. on likely path to regulating greenhouse gas emissions

In an April 2007 landmark decision that will have major implications for U.S.-based power utilities, the United States Supreme Court in Massachusetts v. Environmental Protection Agency (EPA) ruled that the U.S. Environmental Protection Agency has the authority to regulate greenhouse gas emissions, and that the EPA can avoid promulgating such regulations only if it determines that greenhouse gases do not contribute to climate change or if it provides some reasonable explanation as to why it cannot or will not exercise its discretion to determine whether they do. The Supreme Court also held that the petitioners, led by the state of Massachusetts, established “legal standing” to bring the action in federal court. While the ruling involved mobile sources of greenhouse gas emissions, many aspects of the ruling are likely to apply as well to stationary sources of emissions such as power plants.