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The Benson Court’s Approach to Computer Software-or other-Patent Claims Reciting a Mathematical Algorithm


Charles E. Bruzga
© Charles E. Bruzga

This article is based on a talk given by the author on January 17, 1991 to members of the examining corps of the U.S. Patent & Trademark Office. It has been revised to respond to concerns raised at the talk.

About 200 patents on computer software are issued annually by the U.S. Patent & Trademark Office (PTO). [1] Patent claims on computer software frequently recite a mathematical algorithm, or, equivalently, a mathematical formula, [2] which is judicially defined as a “procedure for solving a given type of mathematical problem.” [3]

The patent examining corps has the opportunity to greatly assist in clarifying the standard for determining when a claim reciting a mathematical algorithm is acceptable. This can be done by rejecting overbroad claims under 35 U.S.C. §112, 1st ¶. By an “overbroad” claim is meant a claim whose scope exceeds the “enabling” disclosure of the patent specification, required by §112, 1st ¶. [4]

It is well settled that overbroad claims fail to satisfy 35 U.S.C. §112, 1st ¶. [5] This article points out that the Supreme Court in Gottschalk v. Benson, i.e., the Benson Court, [6] considering claims reciting a mathematical algorithm, applied and discussed the test of avoiding overbroad claims. The article next explains the touchstone of why claims on “transforming or reducing” processes are acceptable, based on prescient reasoning in Benson. Lastly, the article points out why Benson’s test of avoiding overbroad claims facilitates the elusive search for “apparatus” language to make claims per se acceptable.

Currently, claims reciting a mathematical algorithm and being broad in scope have been rejected only under 35 U.S.C. §101, which specifies classes of subject matter eligible for patent protection. [7] Benson’s test of avoiding overbroad claims makes the §101 analysis more precise, by openly considering disclosure scope.

I. Avoiding Overbroad Claims-A Precise, Thorough Test Applied in Gottschalk v. Benson

Gottschalk v. Benson [8] is a landmark case on the acceptability of patent claims reciting a mathematical algorithm. Interest in the case was intense: fourteen amicus briefs on behalf of the computer hardware and software industries and various bar associations were filed with the court. [9] Out of such intense interest arose an opinion submitted as illuminating, due to insightful analyses.

At issue in Benson was the acceptability of claims reciting a mathematical algorithm for converting numbers from one form to another. Claim 8, for instance, which is reproduced at the end of this section, sets forth a “method of converting signals from binary coded decimal formula to binary. ” The disclosure supporting the claims ” related ‘to the processing of data by program and more particularly to the programmed conversion of numerical information’ in general-purpose digital computers’” [10] -apparently the only disclosed embodiment.

A. Comparing Claim Scope to Disclosure Scope

The Benson Court considered the claims as especially broad in scope; it declared that:

Here the “process” claim is so abstract and sweeping as to cover both known and unknown uses of the BCD to pure binary conversion. The end use may *** vary from the operation of a train to verification of drivers’ licenses to research in the law books for precedents***. [11]

The Benson Court viewed the claims as “not limited *** to any particular apparatus or machinery”[12] – i.e. not limited to the disclosed general purpose digital computer. Unmistakenly, the Benson Court directly compared claim and disclosure scopes, pointing out that the claimed end use “may *** be performed through *** future-devised machinery or without any apparatus” [13] – i.e. methods or means beyond the scope of the disclosure.

B. Delineating the Ills of Overbroad Claims

That the claims were far broader than the single disclosed embodiment of a programmed general purpose digital computer is manifest. Lest there be any doubt, the Benson Court immediately proceeds to describe the ills of overbroad claims, most pointedly with respect
to O’Reilly v. Morse. [14]

As noted by the Benson Court, O’Reilly v. Morse concerned a patent to Morse for a process of using electro-magnetism to produce distinguishable signs for telegraphy. Morse was allowed the patent except for the eighth claim, which rather brazenly sought to cover even non-disclosed embodiments. The claim recited the use of “electro-magnetism” however developed for marking or printing intelligible characters, signs, or letters at any distance.” [15] The Benson Court expounded the fundamental ills of the eighth claim, and zeroed in on its overbroad nature, quoting from O’Reilly v. Morse:

“If this claim can be maintained, it matters not by what process or machinery the result is accomplished. For aught that we know some future inventor, in the onward march of science” may discover a mode of writing or printing at a distance by means of the electric or galvanic current, without using any part of the process or combination set forth in the *** specification. His invention may be less complicated-less liable to get out of order-less expensive in construction, and its operation. But yet if it is covered by this patent the [future] inventor could not use it, nor the public have the benefit of it without the permission of the patentee.”[16]

Benson’s analysis of the overbroad claims at issue was precise and thorough, contrasting claim and disclosure scopes, and delineating the fundamental ills of allowing overbroad claims.

C. Adding Precision to Benson’s “Nutshell” Holding

The Benson Court also gave a “nutshell” conclusion, holding that the claims were objectionable because they “would wholly preempt the mathematical formula and in practical effect would [improperly cover] the algorithm itself.” [17] The scope of the claims are at issue with such test; but is the scope of the disclosure also at issue?

“Yes”-according to Benson’s test of avoiding overbroad claims. Reading the nutshell holding in this way gives it more depth and precision, clarifying that the scope of the disclosure is at issue.

Not surprisingly, courts have considered the scope of disclosure, especially when glaringly deficient. Thus in Parker v. Flook [18], the Supreme Court noted:

The patent application does not purport to explain how to select the appropriate margin of safety, the weighting factor, or any of the other variables. Nor does it purport to contain any disclosure relating to the chemical processes at work, the monitoring of process variables, or the means of setting off an alarm or adjusting an alarm system. All that it provides is a formula for computing an updated alarm limit. [19]

Subsequently, the Supreme Court, in Diamond v. Diehr,[20] essentially reiterated the foregoing consideration of disclosure scope by the Flook Court, in distinguishing Flook. [21] More recently, in In re Grams [22], the Court of Appeals for the Federal Circuit also considered disclosure scope:

The specification does not bulge with disclosure. To the contrary, it focuses on the algorithm itself, although it briefly refers to, without describing, the clinical tests that provide data. [23]

Considering disclosure scope-in addition to claim scope-is central to avoiding overbroad claims.

Claim 8 at Issue in Gottschalk v. Benson

8. The method of converting signals from binary coded decimal form into binary which comprises the steps of

(1) storing the binary coded decimal signals in a reentrant shift register,
(2) shifting the signals to the right by at least three places, until there is a binary ‘1’ in the second position of said register,
(3) masking out said binary ‘1’ in said second position of said register,
(4) adding a binary’ l’ to the first position of said register,
(5) shifting the signals to the left by two positions,
(6) adding a ‘1’ to said first position, and
(7) shifting the signals to the right by at least three positions in preparation for a succeeding binary ‘I’ in the second position of said register.

II. Benson’s Clarification of Why “Transforming or Reducing” Claims Are Acceptable

A. The “Transforming or Reducing Test”

In Diamond v. Diehr, [24] the Supreme Court ruled, in an often-applied holding, [25] that “a claim drawn to subject matter otherwise statutory does not become nonstatutory simply because it uses a mathematical formula ***.” [26] A generic example of an “otherwise statutory” claim, according to Diehr, is “transforming or reducing an article to a different state or thing.” [27] In Diehr, the specific “transforming or reducing” was a molding process for transforming raw, uncured synthetic rubber into cured precision products. [28]

In In re Taner, [29] the Court of Customs and Patent Appeals considered “transforming or reducing” an “article” far more ephemeral than rubber: i.e. seismic signals. In that case, a claimed technique of seismic prospecting “involv[ed]”-according to the court-“the taking of substantially spherical seismic signals obtained in conventional seismic exploration and converting *** those signals into another form.” [30]

But what if a claim cannot readily be construed as transforming or reducing an article-Diehr’s example of an “otherwise statutory” claim?

B. Confining Claims to “Definite Bounds”

Again, Benson is illuminating. In reasoning why claims on traditional arts such as tanning, dyeing or vulcanizing rubber are acceptable, Benson pointed out the touchstone feature that made them acceptable:

The chemical process or the physical acts which transform the raw material, are *** sufficiently definite to confine the patent monopoly within rather definite bounds. [31]

In this respect Benson is prescient, anticipating the Diehr Court’s similar view of claim recitations that confine a claim within “definite bounds”:

[Applicants] seek only to foreclose from others the use of [a claimed mathematical] equation in conjunction with all of the other steps in their claimed process. These include installing the rubber in a press, closing the mold, constantly determining the temperature of the mold, [etc.]. [32]

Thus, the touchstone feature of an effective limitation is that it confines the claim within “definite bounds,” rather than necessarily defining a transforming or reducing process. Accordingly, any nonmathematical limitations that serve to so confine a claim should make the claim acceptable where such limitations also avoid the claim being claim overbroad. [33]

III. Facilitating the Elusive Search for Claim Language that is Per Se Acceptable

Method claims, such as those at issue in Gottschalk v. Benson, [34] are nominally analyzed to see if they are “statutory” under 35 U.S.C. §101 [35]. Benson’s test of avoiding overbroad claims, however, is also grounded on the “enablement” provision of 35 U.S.C. §112, [36] although sub silentio. A question facing the practitioner is whether claims in “apparatus” format should also pass Benson’s test of avoiding overbroad claims. Since compliance with §112 is a prerequisite to patent validity, [37] apparatus claims should also comply with §112.

A. The Search for “Truly” Structural Limitations

Treatment of §101 issues by lower courts, which is similar to Benson’s sub silentio §112 treatment at least insofar as both consider claim scope, suggests, somewhat elusively, that claims “truly” in apparatus format might be per se acceptable under §101. Thus, for instance, the court in In re Freeman [38] stated in dictum that:

A claim to a new, useful, and unobvious computer, describing that computer in truly structural terms, would not be rejectable on the ground that the only known use for that computer is the performance of unpatentable methods of calculation.[39] Hence, the real issue is: when is a claim so phrased as to be truly “apparatus” for §101 purposes. Such issue is not fully resolved.

B. Claims Entirely in “Means Plus Function” Form

Thus, as regards apparatus claims drafted entirely with “means plus function” limitations, allowed by 35 U.S.C. §112, 6th ¶ [40], the PTO publicly takes the position that such “means” claims may well “[encompass] any and every means for performing the recited function,” [41] in which case they will be treated as broad as a corresponding method for §101 purposes. [42] “[T]he burden must be placed on the applicant to demonstrate that the claims are truly drawn to specific apparatus,” states the PTO [43], quoting from In re Walter. [44]

Contrary comments concerning such “means plus function” claims appear in In re Iwahashi, [45] which states that each “means” element “‘shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.'” [46] This is more restrictive than the PTO urges. These contrary comments are interpreted by the PTO, however, as merely dicta. [47]

C. “Means Plus Function” Claims Also Reciting Specific Apparatus

Further, Iwahashi, found acceptable under §101 a claim partly reciting “means plus function” elements and partly reciting a “specific piece of apparatus”-i.e. a read only memory. The claim was held to define an “apparatus in the form of a combination of interrelated means,” which “operates according to an algorithm.” [48]

The PTO, however, asserts that “Iwahashi does not ‘hold that the mere presence of apparatus language in a claim will save that claim from rejection as nonstatutory.'” [49] It reasons that-as stated above-the applicant still has the burden of demonstrating that the claims are truly drawn to specific apparatus. [50]

D. Analyzing Both Claim and Disclosure Scopes

The issue thus remains in §101 analysis of when is a claim truly drawn to apparatus. A more insightful analysis can be made by applying Benson’s sub silentio §112 test of avoiding overbroad claims, which, by openly considering disclosure scope, is more precise.

IV. Conclusion

A claim reciting a mathematical algorithm and being overbroad- Leo broader in scope than the enabling disclosure-should be rejected as failing to meet the enablement requirement of 35 U.S.C. §112. This is in accord with the Supreme Court, in Gottschalk v. Benson, [51] applying and discussing the test of avoiding overbroad claims (“Benson’s overbreadth test”). Such test, nominally based on 35 U.S.C. §101, is also based, sub silentio, on §112. Thus, a claim meeting Benson’s overbreadth test satisfies both §101 and the enablement requirement of §112. Overbroad claims can be avoided by including nonmathematical limitations confining the claims to definite bounds, and to the enabled disclosure. Lastly, the elusive search for claim language that will per se make a claim acceptable is facilitated by applying the precise, thorough test of avoiding overbroad claims.

[1] Hamilton, Can Electronic Property Be Protected?, 253 SCIENCE 23 (July 5, 1991) (estimate by the State Bar of Texas).

[2] See e.g., Parker v. Flook, 437 U.S. 584, 586, 198 USPQ 193, 195 (1978).

[3] Gottschalk v. Benson, 409 U.S. 63, 65, 175 USPQ 673, 674 (1972), cited with approval in Parker v. Flook, supra note 2, 437 U.S. at 585 n.1, 198 USPQ at 195 n.1 (1978), and in Diamond v. Diehr, 450 U.S. 175, 186, 209 USPQ 1, 8 (1981).

[4] Section §112, 1st ¶ requires a patent “specification [to] contain a written description of the invention, and of the manner and process of making and using it, in such *** terms as to enable any person skilled in the art *** to make and use the same.”

[5] E.g., In re Hyatt, 708 F.2d 712, 714-15, 218 USPQ 195, 197 (Fed. Cir. 1983); In re Borkowski, 422 F.2d 904, 909-910, 164 USPQ 642, 645-46 (CCPA 1970).

[6] Supra note 3.

[7] The so-called “statutory” classes of subject matter set forth in §101 are “process, machine, manufacture, or composition of matter.”

[8] Supra note 3.

[9] Supra note 3, 409 U.S. at 73 n.7, 175 USPQ at 677 n.7.

[10] Supra note 3, 409 U.S. at 64, 175 USPQ at 674, quoting from the record.

[11] Supra note 3, 409 U.S. at 68, 175 USPQ at 675.

[12] Supra note 3, 409 U.S. at 64, 175 USPQ at 674.

[13] Supra note 3, 409 U.S. at 68, 175 USPQ at 675.

[14] U.S. 65 (15 How. 62)(1853).

[15] Supra note 3, 409 U.S. at 68, 175 USPQ at 675 (emphasis added).

[16] Supra note 3, 409 U.S. at 68, 175 USPQ at 675, quoting from O’Reilly v. Morse, supra note 14, 56 U.S. at 119-120 (15 How. at 113) (emphasis added).

[17] Supra note 3, 409 U.S. at 71-72, 175 USPQ at 676.

[18] Supra note 2.

[19] Supra note 2, 437 U.S. at 586, 198 USPQ at 195.

[20] Supra note 3.

[21] Supra note 3, 450 U.S. at 192 n.14, 209 USPQ at 10 n.14.

[22] 888 F.2d 835, 12 USPQ2d 1824 (Fed. Cir.1989).

[23] Id. at 840, 12 USPQ2d at 1828.

[24] Supra note 3.

[25] In re Grams, supra note 22, 888 F.2d at 839, 12 USPQ2d at 1827; In re Abele, 684 F.2d 902, 907, 214 USPQ 682, 686 (CCPA 1982); and In re Taner, 681 F.2d 787, 791, 214 USPQ 678, 681 (CCPA 1982).

[26] Supra note 3, 450 U.S. at 187, 209 USPQ at 8 (emphasis added).

[27] Supra note 3, 450 U.S. at 192, 209 USPQ at 10.

[28] Supra note 3, 450 U.S. at 177, 209 USPQ at 4.

[29] Supra note 25.

[30] Supra note 25, 681 F.2d at 790, 214 USPQ at 681.

[31] Supra note 3, 409 U.S. at 69, 175 USPQ at 676 (emphasis added).

[32] Supra note 3, 450 U.S. at 187, 209 USPQ at 8 (emphasis added).

[33] See Section I above.

[34] Supra note 3.

[35] Supra note 7.

[36] Supra note 4.

[37] See In re Hyatt, supra note 5; In re Borkowski, supra note 5.

[38] 573 F.2d 1237, 197 USPQ 464 (CCPA 1978).

[39] Id. at 1247 n. 10, 197 USPQ at 472 n. 10 (emphasis added).

[40] Section §112, 6th ¶ permits “an element in a claim for a combination [to] be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof.”

[41] Notice Interpreting In Re Iwahashi (Fed. Cir. 1989), 1112 Official Gazelle 16, 17 (March 13, 1990) (emphasis added).

[42] Id. at 17.

[43] Id.

[44] 618 F.2d 758, 768,205 USPQ 397, 408 (CCPA 1980).

[45] 888 F.2d 1370, 1375 & 1375 n.1, 12 USPQ2d 1908, 1911-12 & 1912 n.1 (Fed. Cir. 1989).

[46] Quoting from 35 U.S.C. §112, 6th ¶.

[47] Supra note 41 at 16-17.

[48] Supra note 45,888 F.2d at 1375, 12 USPQ at 1911.

[49] Supra note 41 at 16-17, quoting from In re Freeman, supra note 38.

[50] Supra note 41 at 17.

[51] Supra note 3.