Attorneys for the federal government and environmentalists argue that a federal appeals court should uphold a ban on new roads in national forests known as the "roadless rule."
The U.S. Department of Agriculture and environmental groups laid out their arguments in documents filed Monday in the 10th Circuit Court of Appeals in Denver.
The 2001 rule applies to at least 40 million acres of forest land.
Lawsuits challenging the rule include one filed by Wyoming. Last year, U.S. District Judge Clarence Brimmer in Cheyenne ruled in that case that the rule wasn't properly implemented.
Wyoming has until Dec. 23 to respond in the 10th Circuit Court. Oral arguments are expected early next year.
The California-based 9th Circuit Court of Appeals upheld the roadless rule in a separate case in August.