Southern Utah Wilderness Alliance v. Dabney

The National Park Service (NPS, defendant) adopted a backcountry-management plan partially closing a road in Canyonlands National Park to vehicles while allowing limited access elsewhere, relying on statutes it argued authorized balancing resource conservation against visitor enjoyment; the Southern Utah Wilderness Alliance (plaintiff) sued, arguing vehicle use would permanently impair the area, and the district court, applying Chevron step one, found the governing statutes clearly barred any 'significant, permanent impairment' of park resources and enjoined vehicle access. Intervenors challenging that injunction argued the statutory language was actually ambiguous and required Chevron step two analysis, while the NPS itself, not appealing but submitting a brief, newly argued 'impairment' meant only temporary impairment — a shift from its district court position — supported by draft management policies published in the Federal Register but not yet finalized.