## Facts

- Inventors filed a patent application for a process to mold raw, uncured synthetic rubber into cured precision products using a molding press.
- The process used thermocouples to measure mold temperature repeatedly, fed measurements into a digital computer, recalculated cure time using the Arrhenius equation, and automatically opened the press when curing was complete.
- The Arrhenius equation and general cure relationships were known, but accurate real-time temperature measurement inside the mold had been difficult in industry practice.
- The patent examiner rejected the claims under 35 U.S.C. § 101 as effectively claiming a computer program or mathematical formula; the PTO Board of Appeals affirmed.
- The Court of Customs and Patent Appeals reversed, and the Supreme Court granted certiorari.

## Issues

1. Whether process claims that include a mathematical formula implemented on a programmed computer constitute patent-ineligible subject matter under 35 U.S.C. § 101.
2. Whether a claim applying a known equation in an industrial rubber-curing method is a patent-eligible “process” rather than an attempt to patent the equation itself.
3. Whether § 101 eligibility analysis may treat the mathematical formula as the “point of novelty” by separating it from the remaining process steps.

## Decision

- The Supreme Court affirmed the judgment that the claims were patent-eligible under § 101.
- The Court held the applicants sought protection for a rubber-curing industrial process, not for the Arrhenius equation in the abstract.
- The Court ruled that a claim otherwise within § 101 does not become ineligible merely because it uses a mathematical formula, computer program, or digital computer.
- The Court required evaluation of the claims “as a whole,” rejecting an approach that dissected steps into old/new or formula/non-formula elements for § 101 purposes.
- The Court distinguished prior cases where claims effectively covered an algorithm itself or treated the formula as the inventive concept.
- Dissenting Justices argued the only alleged novelty was the formula and that the decision risked weakening limits on patenting mathematical formulas.

## Legal Principles

- Laws of nature, natural phenomena, and abstract ideas (including mathematical formulas) are not patentable, but applications of those concepts in a claimed process may be.
- Process claims must be assessed as a whole for § 101 eligibility; it is improper in that analysis to ignore conventional steps and focus only on a formula.
- Applying a mathematical formula within a claimed industrial process that performs a patent-relevant function—such as transforming material into a different state or thing—can satisfy § 101.
- Eligibility under § 101 is distinct from novelty and nonobviousness; whether individual steps were known is generally addressed under §§ 102 and 103, not by collapsing those questions into § 101.

## Conclusion

The Court held that a computer-controlled rubber-curing method that repeatedly measures temperature and applies the Arrhenius equation to determine when to open a press is patent-eligible because it claims an industrial process that transforms uncured rubber into cured products, not the mathematical formula itself.


Diamond v. Diehr, 450 U.S. 175 (1981)