The US Supreme Court rejected Monday a lawsuit that pitted six states against five major power companies accused of emitting greenhouse gases that contribute to climate change. In a big win for the utilities and President Barack Obama\'s administration, the high court ruled the Environmental Protection Agency (EPA) should place restrictions on greenhouse gas emissions, rather than let the matter be legislated in the courts. The Supreme Court -- in an unanimous opinion from eight judges after Justice Sonia Sotomayor recused herself -- rejected an appeals court decision that would have allowed federal judges to place limits on greenhouse gas emissions. \"The critical point is that Congress delegated to EPA the decision whether and how to regulate carbon-dioxide emissions from power plants; the delegation is what displaces federal common law,\" Justice Ruth Bader Ginsburg wrote in a decision on behalf of the court. It marked the most important opinion by the court since a key 2007 ruling that granted the EPA authorization to regulate greenhouse gas emissions. California, Connecticut, Iowa, New York, Rhode Island and Vermont, along with New York City and several private land trusts had argued that global warming harmed the environment and their citizens. They had hoped their suit would go to trial. The utilities -- American Electric Power Co Inc, Southern Co, Xcel Energy Inc, Duke Energy Corp and Tennessee Valley Authority -- together are blamed for 10 percent of US greenhouse gas emissions. The United States is one of the world\'s biggest polluters. Ginsburg said that if the plaintiffs are not satisfied with an EPA decision, they can seek to have their case reviewed in court under the Clean Air Act. \"The Act itself thus provides a means to seek limits on emissions of carbon dioxide from domestic power plants -- the same relief the plaintiffs seek by invoking federal common law,\" she added. \"We see no room for a parallel track.\" The case stemmed from a 2004 lawsuit in which the states had claimed the electric utilities were major polluters and sought to have a federal judge order the companies to cut their emissions of carbon dioxide.