Diamond v. Diehr

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Diamond v. Diehr
Seal of the United States Supreme Court.svg
Argued October 14, 1980
Decided March 3, 1981
Full case name Diamond, Commissioner of Patents and Trademarks v. Diehr, et al.
Citations 450 U.S. 175 (more)
101 S. Ct. 1048; 67 L. Ed. 2d 155; 1981 U.S. LEXIS 73; 49 U.S.L.W. 4194; 209 U.S.P.Q. (BNA) 1
Prior history Certiorari granted [445 U.S. 926]
A machine controlled by a computer program was patentable.
Court membership
Case opinions
Majority Rehnquist, joined by Burger, Stewart, White, Powell
Dissent Stevens, joined by Brennan, Marshall, Blackmun
Laws applied
35 U.S.C. § 101

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. The high court reiterated its earlier holdings that mathematical formulas in the abstract could not be patented, but it held that the mere presence of a software element did not make an otherwise patent-eligible machine or process un-patentable. Diehr was the third member of a trilogy of Supreme Court decisions on the patent-eligibility of computer software related inventions.[1]


The problem and its solution[edit]

The inventors, respondents, filed a patent application for 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. Using the Arrhenius equation

k = A e^{{-E_a}/{RT}} , which may be restated as ln(v) = CZ + x

it is possible to calculate when to open the press and to remove the cured, molded rubber. The problem was that there was, at the time the invention was made, no disclosed way to obtain an accurate measure of the temperature without opening the press.

The invention solved this problem by using embedded thermocouples to constantly check the temperature, and then feeding the measured values into a computer. The computer then used the Arrhenius equation to calculate when sufficient energy had been absorbed so that the molding machine should open the press.

The claims[edit]

Independent claim 1 of the allowed patent is representative. It provides:

1. A method of operating a rubber-molding press for precision molded compounds with the aid of a digital computer, comprising:

  • providing said computer with a data base for said press including at least, natural logarithm conversion data (ln), the activation energy constant (C) unique to each batch of said compound being molded, and a constant (x) dependent upon the geometry of the particular mold of the press,
  • initiating an interval timer in said computer upon the closure of the press for monitoring the elapsed time of said closure,
  • constantly determining the temperature (Z) of the mold at a location closely adjacent to the mold cavity in the press during molding,
  • constantly providing the computer with the temperature (Z),
  • repetitively performing in the computer, at frequent intervals during each cure, integrations to calculate from the series of temperature determinations the Arrhenius equation for reaction time during the cure, which is
where v is the total required cure time,
  • repetitively comparing in the computer at frequent intervals during the cure each said calculation of the total required cure time calculated with the Arrhenius equation and said elapsed time, and
  • opening the press automatically when a said comparison indicates completion of curing.

Proceedings before Office and CCPA[edit]

The patent examiner rejected this invention as unpatentable subject matter under 35 U.S.C. 101. He argued that the steps performed by the computer were unpatentable as a computer program under Gottschalk v. Benson, 409 U.S. 63 (1972). The Board of Patent Appeals and Interferences of the USPTO affirmed the rejection. The Court of Customs and Patent Appeals (CCPA), the predecessor to the current Court of Appeals for the Federal Circuit, reversed, noting that an otherwise patentable invention did not become unpatentable simply because a computer was involved.

The U.S. Supreme Court granted the petition for certiorari by the Commissioner of Patents and Trademarks to resolve this question.

The Supreme Court's opinion[edit]

The court repeated its earlier holding that mathematical formulas in the abstract are not eligible for patent protection. But it also held that a physical machine or process which makes use of a mathematical algorithm is different from an invention which claims the algorithm, as such, in the abstract. 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.

The reversal of the patent rejection was affirmed. But the Court carefully avoided overruling Benson or Flook. It did criticize the analytic methodology of Flook, however, by challenging its use of analytic dissection, based on Neilson v. Harford. The Diehr Court said, without citation of any supporting authority, that under section 101 the invention had to be considered as a whole.[2]

The patent[edit]

The patent that issued after the decision was US 4344142 , "Direct digital control of rubber molding presses." The patent includes 11 method claims, three of which are independent. All method claims relate to molding of physical articles.


  1. ^ The other two cases were Gottschalk v. Benson, 409 U.S. 63 (1972), and Parker v. Flook, 437 U.S. 584 (1978). The Supreme Court's most recent decision on patent-eligibility is Bilski v. Kappos, a case concerning business methods.
  2. ^ Section 103, which concerns obviousness, states that the obviousness or non-obviousness of what is claimed to be an invention must be determined by considering whether "the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made." No comparable language is found in section 101, which has retained substantially the same form since the first patent act in 1790.

See also[edit]

  • Research Corp. Technologies v. Microsoft Corp., No. 2010-1037 (Fed. Cir., Dec. 8, 2010).

External links[edit]