450 U.S. 175 (1981)
In August 1975 respondents Diehr and Lutton filed a patent application describing a process for molding raw uncured synthetic rubber into cured precision products.1 The claimed method begins with loading a mold with uncured rubber.2 It closes the press. It constantly measures the actual temperature inside the mold cavity with a thermocouple.3 It feeds each measurement into a digital computer that repeatedly solves the Arrhenius equation to recalculate the required cure time.4 It compares the recalculated time to elapsed time.5 It automatically opens the press when the two values match.6
The application explained that conventional industry practice calculated cure time as the shortest period guaranteed to cure every part of the product.7 Mold temperature had been treated as an uncontrollable variable.8 The shortcoming of this practice is that operating with an uncontrollable variable inevitably led in some instances to overestimating the mold-opening time and overcuring the rubber, and in other instances to underestimating that time and undercuring the product.9
Respondents claimed that their continuous temperature monitoring and computer recalculation were new in the art.10
The patent examiner rejected all claims on the sole ground that they sought protection for nonstatutory subject matter under 35 U.S.C. § 101.11 He concluded that the computer-performed steps were unpatentable under Gottschalk v. Benson.12 The remaining steps of installing and closing the rubber were conventional.13 The Patent and Trademark Office Board of Appeals affirmed the rejection.14
The Court of Customs and Patent Appeals reversed in In re Diehr, 602 F.2d 892 (1979).15 The Commissioner of Patents and Trademarks petitioned for certiorari.16 The Supreme Court granted certiorari.
Whether a process for curing synthetic rubber which includes in several of its steps the use of a mathematical formula and a programmed digital computer is patentable subject matter under 35 U.S.C. § 101?17
Section 101 of the Patent Act provides that whoever invents or discovers any new and useful process may obtain a patent.18 A process is patentable when it transforms an article into a different state or thing.19 The presence of a mathematical formula or programmed digital computer does not render an otherwise statutory claim unpatentable.20 This is true so long as the claim as a whole is directed to the process and does not preempt the formula in the abstract.21
Yes. Respondents' process begins with loading a mold with raw uncured synthetic rubber.22 It ends with the automatic opening of the press once the recalculated cure time matches elapsed time, thereby transforming the rubber into a cured precision product.23 Although the process employs the Arrhenius equation solved repeatedly by a digital computer, the claims also recite the steps of constantly measuring mold temperature with a thermocouple and using those measurements to control the press.24 The invention as a whole constitutes an industrial manufacturing process of the type historically eligible for patent protection.25
The examiner's rejection under Benson treated the computer steps in isolation.26 The claims do not seek to patent the equation itself but instead limit its use to this specific rubber-curing method.27
The claimed process constitutes patentable subject matter under 35 U.S.C. § 101.28
Related opinions on this issue
Joined by Brennan, Marshall, And Blackmun, Jj.
Justice Stevens dissented.29 He argued that Diehr and Lutton claimed nothing more than an improved method of calculating cure time.30 They did so by repetitively solving the Arrhenius equation on a digital computer in response to temperature variations.31
He viewed the invention as functionally identical to the unpatentable alarm-limit calculation in Parker v. Flook.32 The only difference was claim drafting that added conventional postsolution activity.33 Stevens argued that the majority mischaracterized the claims as disclosing a new method of temperature measurement.34
The application in fact disclosed no novel instrumentation.35 The decision improperly conflated the § 101 inquiry with the separate question of novelty under § 102.36