Intellectual Property Rights

Diamond v. Diehr

450 U.S. 175 (1981)

Facts

Diehr and Lutton developed a process for curing synthetic rubber.
Proper curing required the mould to remain closed for the correct period.
Earlier methods relied upon estimated temperatures and often produced undercured or overcured rubber.
The applicants placed temperature sensors inside the mould.
A computer repeatedly measured temperature and applied the known Arrhenius equation to calculate the correct curing time.
The computer then signalled when the mould should open.
The Patent Office rejected the claims because they used:
a mathematical formula;
a computer program.
The dispute reached the United States Supreme Court.

Whether a process becomes unpatentable because it uses a mathematical equation or computer.
Whether the claim concerned the Arrhenius formula itself or an industrial rubber-curing process.
Whether the invention was patent-eligible subject matter.

Mathematical formulas, laws of nature and abstract ideas cannot be patented in isolation.
A practical process applying such a principle may be patentable.
Patent claims must be considered as a whole.
Courts should not remove known or mathematical elements and then assess only what remains.
A process is potentially patent eligible where it:
transforms or treats physical material;
uses a formula as part of a concrete industrial procedure;
does not seek to monopolise the formula for every use.
Patent eligibility is separate from novelty and obviousness.

The applicants did not claim ownership of the Arrhenius equation.
Others remained free to use that formula in scientific and industrial contexts.
The patent claim covered a complete rubber-curing process involving:
placing uncured rubber in a mould;
continuously measuring actual temperature;
repeatedly recalculating curing time;
automatically opening the mould at the proper moment.
The process physically transformed raw rubber into a cured manufactured product.
The computer improved the accuracy and reliability of that transformation.
The Patent Office had treated the computer-related step as though it automatically disqualified the claim.
The Supreme Court rejected that approach.
A new industrial process does not become abstract merely because one of its stages involves mathematical calculation.
Similarly, the fact that individual components were known did not decide subject-matter eligibility.
Novelty and inventive step had to be examined separately under the appropriate statutory provisions.
The Court distinguished earlier cases in which applicants effectively claimed mathematical algorithms without limiting them to a concrete technological process.
Here, the formula was tied to a specific industrial application and could not be used to pre-empt every application of the equation.
The claim therefore fell within the statutory category of a process.

The Supreme Court held that the rubber-curing process was patent-eligible subject matter.
Use of a computer and mathematical formula did not invalidate a claim directed to a concrete physical process.
The application returned for examination of the remaining patentability requirements.
Use this case for: an abstract formula cannot be patented alone, but its specific application within a physical industrial process may be patent eligible.