Appeals court hears arguments on clean power case

the “best system of emissions reduction,” and whether Congress meant the word “system” to apply only to the machinery inside power plants or more broadly to the various ways that electricity can be generated and transmitted to customers.

Justice Department lawyer Eric Hostetler said EPA was simply requiring what the free market is already doing.

The nationwide demand for coal has plummeted as utilities shift to cleanerburning natural gas made available through hydraulic fracturing and the cost of installing new wind and solar facilities decreases. In many parts of the United States, generating a kilowatt of emissions-free electricity is now the cheaper than that produced by carbon-spewing coal boilers.

“This rule addresses the key environmental challenge of our time, and does so cost effectively,” Mr. Hostetler said.

The judges repeatedly interrupted the lawyers for both sides to ask pointed questions about the legal underpinnings of their positions.

Under the Clean Air Act, certain challenges to new EPA rules skip the federal district court and go directly to the appeals court. A threejudge panel had been scheduled to hear the case in June, but for issues involving “a question of exceptional importance” procedural rules allow for the case to proceed directly to a hearing before the full appeals court, known as an “en banc” review.

By using its discretion to skip a step, the appeals judges are potentially shaving months off the time before the case could be heard by the high court.

Six of the 10 appeals judges on the D.C. Circuit were appointed by Democratic presidents. Chief Judge Merrick Garland, who was nominated by Obama to fill a vacant Supreme Court seat, recused himself from the case.