Eight states and three private land trusts brought an action invoking the federal common law of public nuisance seeking to create an annual declining cap on greenhouse gas emissions. The EPA does not presently regulate such emissions. The US Supreme Court on Monday ruled in American Electric Power v Connecticut that a claim regarding greenhouse gasses cannot be brought under the legal framework of nuisance. The court held that to challenge greenhouse gas emissions the plaintiffs may file petitions for rule-making with the EPA to set emissions standards. By the time this case reached the Supreme Court, the EPA had already begun the rule-making process on the issue and is set to issue new standards by May 2012.