The National Association of Home Builders, the County of San Bernardino, and others (plaintiffs) filed suit in federal court against Bruce Babbitt, in his official capacity as Secretary of the Interior, the U.S. Fish and Wildlife Service, and others (defendants), seeking declaratory and injunctive relief and challenging the application of § 9(a)(1) of the Endangered Species Act (ESA) to the endangered Delhi Sands Flower-Loving Fly (the Fly). The Fly’s habitat was located exclusively in an area where plaintiffs sought to build a large hospital complex. Plaintiffs claimed application of the statute to the Fly exceeded Congress’ authority under the Commerce Clause. The district court disagreed and entered summary judgment in favor of defendants. Plaintiffs appealed.