Diamond v. Diehr, 450 U.S. 175 (1981), was a United States Supreme Court decision which held that controlling the execution of a physical process, by running a computer program did not preclude patentability of the invention as a whole.

Diehr was the third member of a trilogy of Supreme Court decisions on the patent-eligibility of computer software related inventions.

The application claimed a "[process] for molding raw, uncured synthetic rubber into cured precision products."

The process of curing synthetic rubber depends on a number of factors including time, temperature and thickness of the mold.

The invention solved this problem by using embedded thermocouples to constantly check the temperature, and then feeding the measured values into a computer.

A method of operating a rubber-molding press for precision molded compounds with the aid of a digital computer, comprising: The patent examiner rejected this invention as unpatentable subject matter under 35 U.S.C.

Source:[9] The Court repeated its earlier holding that mathematical formulas in the abstract are not eligible for patent protection.

Thus, if the invention as a whole meets the requirements of patentability—that is, it involves "transforming or reducing an article to a different state or thing"—it is patent-eligible, even if it includes a software component.

In Diehr, by contrast [with Flook], we held that a computer-implemented process for curing rubber was patent eligible, but not because it involved a computer.

The invention in Diehr used a "thermocouple" to record constant temperature measurements inside the rubber mold — something "the industry ha[d] not been able to obtain."

The temperature measurements were then fed into a computer, which repeatedly recalculated the remaining cure time by using the mathematical equation.