In a move observers say could have big implications for U.S. climate-change policy, five large electric utilities said on March 16 that they will ask the U.S. Supreme Court to overturn a lower-court ruling that subjects them to lawsuits claiming that their carbon-dioxide emissions cause health problems, coastal erosion and other climate-change impacts. The utilities—American Electric Power, Southern Co., Tennessee Valley Authority, Xcel Energy and Cinergy, a unit of Duke Energy—said in court papers obtained by Platt’s (like ENR, a unit of the McGrawHill Cos.) that the high court should hear their case because it presents “substantial constitutional and jurisprudential questions” on U.S. climate-change policy. The firms say that if their appeal is rejected, lower courts could order electric utilities and perhaps other smokestack industries to implement “a regulatory regime of carbon dioxide-emission caps and emission-reduction requirements.” Utilities have 90 days to file their appeal.