In 1999, United States Customs inspectors seized a shipment of hoasca to the O Centro Espirita Beneficente Uniao do Vegetal (UDV) (plaintiff), a Christian Spiritist sect based in Brazil with an American branch of approximately 130 people. Hoasca was a sacramental tea made from plants unique to the Amazon region, and contained a hallucinogen regulated under the Controlled Substances Act (CSA), 21 U.S.C. § 801. The UDV brought suit for declaratory and injunctive relief against Attorney General Alberto Gonzales (defendant) and the United States government (Government) (defendant), seeking to enjoin the enforcement of the CSA’s prohibition of hoasca against the UDV members. The UDV relied on the Religious Freedom Restoration Act of 1993 (RFRA), 42 U.S.C. § 2000bb-1(b), which prohibited the Government from substantially burdening a person’s religious exercise unless the Government demonstrated that the application of the burden to the person was the least restrictive means of advancing a compelling interest. Prior to trial, the UDV sought a preliminary injunction so that the UDV could practice its faith pending the merits. At the hearing on the preliminary injunction, the Government conceded that applying the CSA to the UDV’s use of hoasca substantially burdened the UDV’s sincere religious exercise. However, the Government argued that this application did not violate the RFRA because the application was the least restrictive means of advancing the compelling interests of (1) protecting the UDV members’ health and safety, (2) preventing the diversion of hoasca from church members to recreational users, and (3) complying with the 1971 United Nations Convention on Psychotropic Substances (Convention). The district court heard evidence from both parties on the risks of hoasca and the potential for diversion from the UDV, and concluded that the evidence on both issues was “in equipoise” and “virtually balanced.” Because the evidence was evenly balanced, the district court held that the Government had not met its burden of demonstrating a compelling interest justifying a substantial burden on the UDV’s sincere religious exercise. The district court also rejected the argument based on the Convention, holding that the Convention did not apply to hoasca. Accordingly, the district court granted the preliminary injunction. The Government appealed, and a panel of the United States Court of Appeals for the Tenth Circuit affirmed. A majority of the Tenth Circuit sitting en banc then affirmed again. The Government petitioned for certiorari, arguing that although the Government would bear the burden of establishing a compelling interest at trial, the UDV bore the burden of disproving the alleged compelling interest at the preliminary-injunction hearing. The United States Supreme Court granted certiorari.