Ruling could cost utility companies billions.

Byline: Kristin McAllister

Apr. 3--Two rulings by the U.S. Supreme Court on Monday could eventually cost utility companies billions of dollars, energy experts said.

By unanimous decision, the high court ruled against Charlotte, N.C.-based Duke Energy in a lawsuit stemming from the Clinton administration that targets the utilities industries and forces them to add pollution control equipment to aging coal-fired power plants.

In the Duke case, justices ruled that the 4th U.S. Circuit Court of Appeals in Richmond, Va., overstepped its authority by interpreting 1980 Environmental Protection Agency regulations in a way that favored Duke.

The …