She noted that the lands environmentalists are trying to protect were passed over when Congress in the 1970s gave the BLM 15 years to inventory its land and recommend parcels that should be federal wilderness, which is off-limits to roads, development and motorized vehicles.

In 1991, the BLM recommended that Congress designate 9.6 million acres of 22.8 million acres it assessed as wilderness; another 15.5 million acres were classified as wilderness study areas, which protects them until Congress acts.

The Bush administration argues that the 15-year inventory period ended in 1991. Officials said setting aside more potential wilderness areas would violate the Federal Land Policy and Management Act.

Norton wrote in an April 11, 2003, letter to Sen. Bob Bennett, R-Utah, that wilderness areas are managed for a single use "and that any administrative decision to manage other lands as 'wilderness areas' outside of the 1964 Wilderness Act violates clear congressional direction."

Interior Department spokesman John Wright said the BLM can still evaluate land and manage it to maintain wilderness characteristics through its planning process, which includes public input.

Angell of Earthjustice said the Bush administration's interpretation of the law is significantly different from other administrations — Republican and Democratic. He will argue in court that resolving the issue through a court-sanctioned settlement is unconstitutional because it's binding on future administrations.

Angell added that the 15-year period for the BLM inventory was intended simply as a deadline, not "the close of a window."