On June 30, the U.S. Supreme Court limited the authority of the U.S. Environmental Protection Agency (EPA) to utilize the Clean Air Act to shift electric power production to sources with lower greenhouse gas emissions. Relying on the "major questions doctrine," the court in West Virginia v. EPA held that in the absence of clear Congressional authorization, the EPA could not lawfully promulgate regulations that would transform a sector of the economy by requiring coal-fired power plants to reduce their production or to subsidize natural gas, wind or solar sources. The Supreme Court thus returned the climate debate to a reluctant Congress.