Editors' Summary: The Bureau of Land Management is in the process of reviewing 23.8 million acres of its lands for possible wilderness designation. During this review it must manage these wilderness study areas under §603(c), an ambiguous provision which mandates the application of a strict nonimpairment standard to WSAs but "grandfathers" certain poorly-defined pre-FLPMA activities. In 1978, the Solicitor of the Department of the Interior wrote a legal opinion construing the provision to provide stringent limits on oil and gas leasing in WSAs. In a challenge to this policy, oil and gas interests won an overwhelming victory in district court, but late in 1982, the Tenth Circuit reversed. While better reasoned than the district court's decision, the Tenth Circuit failed to resolve an important issue which troubled the district court: to what extent does §701(h), which protects "valid existing rights," limit the applicability of the nonimpairment standard. A 1981 Solicitor's opinion, modifying the 1978 opinion's discussion of "valid existing rights" further complicates the question, and will likely lead to more litigation before the issue is resolved.