By Stephen Henderson MCT

WASHINGTON – The Supreme Court on Wednesday wrestled with the thorny issues surrounding global warming and the government’s efforts to abate it. But hour-long arguments at the high court – at times heavy with discussion of the science of climate change – left little indication of how the court will ultimately rule.

At issue in Massachusetts v. EPA are two simple questions: Whether the Clean Air Act authorizes the Environmental Protection Agency to regulate air pollutants that contribute to climate change; and if so, whether the EPA properly used its discretion when it chose not to regulate auto emissions.

Also at stake in the case is whether states, many of which claim climate change will harm their land and citizens, have the right to sue to force EPA action on pollutants from cars and other sources.

The case is the high court’s first foray into the argument over global warming, and its ruling could have far-reaching effects. If the justices determine that EPA is not responsible for regulating greenhouse gases, it would likely require congressional intervention to initiate government action. If the justices decide that states don’t have standing to sue, that would undercut other pending suits seeking to regulate factory emissions and generally make it more difficult for environmental claims to go forward.

Environmental groups – pushing for EPA regulation – and business interests – trying to keep government regulation to a minimum – have both described it as the most significant environmental case in a generation.

In political terms, the justices appeared to cleave along familiar lines. More conservative justices like Antonin Scalia, Samuel Alito and Chief Justice John Roberts appeared skeptical of the EPA’s authority and states’ rights to sue. Justice Clarence Thomas, who rarely speaks during oral arguments, is expected to join other conservatives in this case.

Meanwhile, Justices John Paul Stevens, David Souter, Ruth Bader Ginsburg and Stephen Breyer were more accepting of both ideas.

That would leave Justice Anthony Kennedy as the critical fifth vote to decide both issues, a role he increasingly plays, with the departure of the court’s other swing voter, Sandra Day O’Connor.