A federal appeals court Wednesday blocked road construction in at least 40 million acres of pristine national forests.

The decision by a three-judge panel of the 9th Circuit Court of Appeals reinstates most of a 2001 rule put in place by President Bill Clinton just before he left office that prohibited commercial logging, mining and other development on about 58 million acres of national forest in 38 states and Puerto Rico. A subsequent Bush administration rule had cleared the way for more commercial activity there.

The latest ruling, issued in San Francisco, sides with several Western states and environmental groups that sued the Forest Service after it reversed the so-called "Roadless Rule" in 2005.

But it is not the final word on roadless forests.

A separate case is pending in the 10th Circuit Court of Appeals, where environmental groups are appealing a Wyoming district court decision repealing the Clinton roadless rule.

"It's up and down like a yo-yo," said Tom Partin, president of the American Forest Resource Council, a timber industry group. "It seems to be bouncing from one court to the other."

The Obama administration cited that legal uncertainty this spring in ordering a one-year moratorium on most road-building in national forests.