Diehr (applicant) filed a patent application that claimed a process for curing rubber. The process included mathematical calculations such as the well known Arrhenius equation. The patent examiner rejected the claims as unpatentable under 35 U.S.C. §101 because they were directed to mathematical formulas, and because the non-mathematical steps were necessary to the process and thus improper bases for patentability. Diehr appealed to the Court of Customs and Patent Appeals, which reversed. Diamond (petitioner), the Commissioner of Patents, filed a writ of certiorari with the United States Supreme Court, which was granted.