The EPA tried to inspect Stauffer's Tennessee plants with private contractors. Stauffer refused entrance to the plant in that private contractors are not authorized representatives as the term is used in the Clean Air Act. Stauffer also argued that the United States should be estopped from litigating this issue in that the Government had already lost a court case in Wyoming on this very same issue against Stauffer. The Court of Appeals agreed with Stauffer. The Supreme Court granted certiorari.