Arrhythmia Research Technology Inc. v. Corazonix Corp., 1992
The invention was directed to the analysis of electrocardiographic signals in order to determine certain characteristics of the heart function. Dr. Simson, a cardiologist, had sought a solution to the problem of determining which heart attack victims are at high risk for ventricular tachycardia, so that these persons can be carefully monitored and appropriately treated.
Certain steps of the invention were described as being conducted with the aid of a digital computer, and the patent specification set forth the mathematical formulae that were used to configure (program) the computer. The specification stated that dedicated, specific purpose equipment or hard wired logic circuitry can also be used.
The district court held that the method and apparatus claims of the Simpson patent are directed to a mathematical algorithm, and thus do not define statutory subject matter. Claim 1 was the broadest method claim:
1. A method for analyzing electrocardiograph signals to determine the presence or absence of a predetermined level of high frequency energy in the late QRS signal, comprising the steps of:
converting a series of QRS signals to time segments, each segment having a digital value equivalent to the analog value of said signals at said time;
applying a portion of said time segments in reverse time order to high pass filter means;
determining an arithmetic value of the amplitude of the output of said filter; and
comparing said value with said predetermined level.
Claim 7 was a representative apparatus claim:
7. Apparatus for analyzing electrocardiograph signals to determine the level of high frequency energy in the late QRS signal comprising:
means for converting X, Y, and Z lead electrocardiographic input signals to digital valued time segments;
means for examining said X, Y, and Z digital valued time segments and selecting therefrom the QRS waveform portions thereof;
means for signal averaging a multiplicity of said selected QRS waveforms for each of said X, Y, and Z inputs and providing composite, digital X, Y, and Z QRS waveforms;
high pass filter means;
means for applying to said filter means, in reverse time order, the anterior portion of each said digital X, Y, and Z waveform; and
means for comparing the output of said filter means with a predetermined level to obtain an indication of the presence of a high frequency, low level, energy component in the filter output of said anterior portions.
The Patent and Trademark Office had granted the patent without questioning that its claims were directed to statutory subject matter under Section 101.
The Federal Circuit stated that whether a claim is directed to statutory subject matter is a question of law.
The Federal Circuit recognized that Supreme Court has observed that Congress intended section 101 to include “anything under the sun that is made by man.” Diamond v. Chakrabarty, 447 U.S. 303, 309, 206 USPQ 193, 197 (1980), quoting S. Rep. No. 1979, 82d Cong., 2d Sess., 5 (1952); H.R. Rep. No. 1923, 82d Cong., 2d Sess., 6 (1952). There are, however, qualifications to the apparent sweep of this statement. Excluded from patentability is subject matter in the categories of “laws of nature, physical phenomena, and abstract ideas”. Diamond v. Diehr,450 U.S. 175, 185, 209 USPQ 1, 7 (1981). A mathematical formula may describe a law of nature, a scientific truth, or an abstract idea. As courts have recognized, mathematics may also be used to describe steps of a statutory method or elements of a statutory apparatus. The exceptions to patentable subject matter derive from a lengthy jurisprudence, but their meaning was probed anew with the advent of computer-related inventions.
The Federal Circuit then noted that in Gottschalk v. Benson, 409 U.S. 63, 72, 175 USPQ 673, 676 (1972) the Court held that a patent claim that “wholly pre-empts” a mathematical formula used in a general purpose digital computer is directed solely to a mathematical algorithm, and therefore does not define statutory subject matter under section 101. The Court described the mathematical process claimed in Benson as “so abstract and sweeping as to cover both known and unknown uses of the BCD [binary coded decimal] to pure binary conversion.”
The court then noted that in Parker v. Flook, 437 U.S. 584, 591, 198 USPQ 193, 198 (1978) the Court explained that the criterion for patentability of a claim that requires the use of mathematical procedures is not simply whether the claim “wholly pre-empts” a mathematical algorithm, but whether the claim is directed to a new and useful process, independent of whether the mathematical algorithm required for its performance is novel. Applying these criteria the Court held nonstatutory a method claim for computer-calculating “alarm limits” for use in a catalytic conversion process, on the basis that “once that algorithm is assumed to be within the prior art, the application, considered as a whole, contains no patentable invention.” Flook, 437 U.S. at 594, 198 USPQ at 199.
The Federal Circuit then noted that in Diamond v. Diehr the Court explained that non-statutory status under section 101 derives from the “abstract”, rather than the “sweeping”, nature of a claim that contains a mathematical algorithm. The Court stated:
“While a scientific truth, or the mathematical expression of it, is not a patentable invention, a novel and useful structure created with the aid of knowledge of scientific truth may be.”
The mathematical algorithm in Diehr was the known Arrhenius equation, and the Court held that when the algorithm was incorporated in a useful process, the subject matter was statutory. The Court confirmed the rule that process steps or apparatus functions that entail computer-performed calculations, whether the calculations are described in mathematical symbols or in words, do not of themselves render a claim nonstatutory. In Diehr, the Court clarified its earlier holdings, stating that “[I]t is inappropriate to dissect the claims into old and new elements and then to ignore the presence of the old elements in the [section 101] analysis.”
The Court thus placed the patentability of computer-aided inventions in the mainstream of the law. The ensuing mode of analysis of such inventions was summarized in In re Meyer, 688 F.2d 789, 795, 215 USPQ 193, 198 (CCPA 1982):
In considering a claim for compliance with 35 USC 101, it must be determined whether a scientific principle, law of nature, idea, or mental process, which may be represented by a mathematical algorithm, is included in the subject matter of the claim. If it is, it must then be determined whether such principle, law, idea, or mental process is applied in an invention of a type set forth in 35 USC 101.
The law crystallized about the principle that claims directed solely to an abstract mathematical formula or equation, including the mathematical expression of scientific truth or a law of nature, whether directly or indirectly stated, are nonstatutory under section 101; whereas claims to a specific process or apparatus that is implemented in accordance with a mathematical algorithm will generally satisfy section 101.
In applying this principle to an invention whose process steps or apparatus elements are described at least in part in terms of mathematical procedures, the mathematical procedures are considered in the context of the claimed invention as a whole. Determination of statutory subject matter has been conveniently conducted in two stages, following a protocol initiated by the Court of Customs and Patent Appeals in In re Freeman, 573 F.2d 1237, 197 USPQ 464 (CCPA 1978); modified after the Court’s Flook decision by In re Walter, 618 F.2d 758, 205 USPQ 397 (CCPA 1980); and again after the Court’s Diehr decision by In re Abele, 684 F.2d 902, 214 USPQ 682 (CCPA 1982).
This analysis has been designated the Freeman-Walter-Abele test for statutory subject matter. It is first determined whether a mathematical algorithm is recited directly or indirectly in the claim. If so, it is next determined whether the claimed invention as a whole is no more than the algorithm itself; that is, whether the claim is directed to a mathematical algorithm that is not applied to or limited by physical elements or process steps. Such claims are nonstatutory. However, when the mathematical algorithm is applied in one or more steps of an otherwise statutory process claim, or one or more elements of an otherwise statutory apparatus claim, the requirements of section 101 are met. The court in Abele explained that:
Walter should be read as requiring no more than that the algorithm be “applied in any manner to physical elements or process steps,” provided that its application is circumscribed by more than a field of use limitation or non-essential post-solution activity.
Although the Freeman-Walter-Abele analysis is not the only test for statutory subject matter, and the Federal Circuit stated that failure to meet that test may not always defeat the claim, the Federal Circuit found that this analytic procedure was conveniently applied to the Simson invention.
Applying the Freeman-Walter-Abele protocol to the process claims, the Federal Circuit accepted the proposition that a mathematical algorithm is included in the subject matter of the process claims in that some claimed steps are described in the specification by mathematical formulae. The Court thus proceeded to the second stage of the analysis, to determine whether the claimed process is otherwise statutory.
Simson’s process was claimed as a “method for analyzing electrocardiograph signals to determine the presence or absence of a predetermined level of high-frequency energy in the late QRS signal”. This claim limitation was not ignored in determining whether the subject matter as a whole is statutory, for all of the claim steps are in implementation of this method. The electrocardiograph signals are first transformed from analog form, in which they are obtained, to the corresponding digital signal. These input signals are not abstractions; they are related to the patient’s heart function.
The Federal Circuit took the position that the claimed steps of “converting”, “applying”, “determining”, and “comparing” were physical process steps that transform one physical, electrical signal into another and that the Freeman-Walter-Abele standard was met, for the steps of Simson’s claimed method comprise an otherwise statutory process whose mathematical procedures are applied to physical process steps.
The apparatus claims require a means for converting the electrocardiograph signals from the analog form in which they are generated into digital form.
The use of mathematical formulae or relationships to describe the electronic structure and operation of an apparatus does not make it nonstatutory. Iwahashi, 888 F.2d at 1375, 12 USPQ2d at 1911.
The Federal Circuit therefore concluded that the Simson apparatus claims satisfied the criteria for statutory subject matter.
After this case was decided, practitioners such as myself went out of our way to include A-D or D-A converters in our application. Many examiners, however, still would routinely issue 101 rejections if they saw an algorithm in a patent application.
The concurrence to this case by Judge Rader was also quite interesting:
Nearly twenty years ago, in Gottschalk v. Benson, 409 U.S. 63 [175 USPQ 458] (1972), the Supreme Court dealt with a computer process for conversion of binary coded decimals into pure binary numbers was not patentable subject matter. Benson held this mathematical algorithm ineligible for patent protection. 409 U.S. at 65, 71-72. Because computer programs rely heavily on mathematical algorithms, commentators saw dire implications in the Supreme Court’s opinion for patent protection of computer software. For instance, one treatise, citing Benson, stated:
[A] recent Supreme Court decision seemingly eliminated patent protection for computer software.
Donald S. Chisum, Patents Section 1.01 (1991); see also id. at Section 1.03 [6].
The court upholds the ‘459 patent by applying a permutation of the Benson algorithm rule. In reaching this result, the court adds another cord to the twisted knot of precedent encircling and confining the Benson rule. While fully concurring in the court’s result and commending its ability to trace legal strands through the tangle of post-Benson caselaw, I read later Supreme Court opinions to have cut the Gordian knot. The Supreme Court cut the knot by strictly limiting Benson.
Relying on the language of the patent statute, the Supreme Court in Diamond v. Diehr, 450 U.S. 175 [209 USPQ 1] (1981), turned away from the Benson algorithm rule. Thus, I too conclude that the ‘459 patent claims patentable subject matter – not on the basis of a two-step post-Benson test, but on the basis of the patentable subject matter standards in title 35. Rather than perpetuate a non-statutory standard, I would find that the subject matter of the ‘459 patent satisfies the statutory standards of the Patent Act.