Pedro Perales (plaintiff) filed a claim for disability benefits under the Social Security Act (Act), 42 U.S.C. § 301 et seq., which was administered by the secretary of health, education, and welfare (Secretary) (defendant). After Perales’s claim was denied, he requested a hearing before the Secretary. The administrative record developed at the hearing included testimony by Perales and his doctor, both of whom maintained that Perales was wholly and permanently disabled by a back injury. However, contradictory medical reports indicated that Perales’s treating neurosurgeon and other medical specialists had concluded that his condition was not disabling. Perales made various objections to the rules of evidence applied at the hearing, arguing that the evidence introduced into the record was inadmissible and therefore violated procedural due process. The hearing examiner overruled the objections and concluded that Perales was not disabled under the Act. The appeals council affirmed, and Perales sought review in federal district court. The district court remanded the case to the hearing examiner. The court of appeals affirmed the remand. The United States Supreme Court granted certiorari to review.