The following represents a recent legal analysis done by Associate Solicitor
Lee E. Barrett, an attorney in the Office of the Solicitor of the Patent and
Trademark Office, on the subject of the patentability of mathematical
algorithms and computer programs. The analysis is published for the benefit
of the public.
August 9, 1989. FRED E. McKELVEY, Solicitor
Table of Contents
I. STATUTORY SUBJECT MATTER: 35 U.S.C. $ 101
II. MATHEMATICAL ALGORITHMS
A. Mathematical algorithms per se are not a statutory "process"
under $ 101
B. Evolution of the two-part test for mathematical
algorithm-statutory subject matter
C. Application of the two-part test
1. Step 1 -- presence of a mathematical algorithm
a. Mathematical algorithm
b. "Process" versus "apparatus" claims
c. Form of the mathematical algorithm
2. Step 2 -- is the mathematical algorithm "applied in any
manner to physical elements or process steps?"
a. Post-solution activity
b. Field of use limitations
c. Data-gathering steps
d. Transformation of something physical
e. Structural limitations in process claims
D. Examples
1. Diamond v. Diehr
2. Parker v. Floor
3. In re Abele
III. COMPUTER PROGRAMS
A. "Computer programs" versus "computer processes"
B. Statutory nature of computer processes
1. The Supreme Court has not ruled on the patentability of
computer programs
2. The CCPA has held that computer processes are statutory
unless they fall within a judicially determined exception
Discussion
I. Statutory Subject Matter: 35 U.S.C. $ 101
Inventions may be patented only if they fall within one of the four
statutory classes of subject matter of 35 U.S.C. $ 101: "process, machine,
manufacture, or composition of matter." See Kewanee Oil Co. v. Bicron Corp.,
416 U.S. 470, 483, 181 USPQ 673, 679 (1974):
[N]o patent is available for a discovery, however useful, novel, and
nonobvious, unless it falls within one of the express categories of
patentable subject matter of 35 U.S.C. $ 101.
Subject matter that does not fall within one of the statutory classes of 35
U.S.C. $ 101 is said to be "nonstatutory" or to be "unpatentable subject
matter." The broad language of $ 101 is intended to delineate a "general
industrial boundary" of patentable invention. In re Bergy, 596 F.2d 952, 974
n.11, 201 USPQ 352, 372 n.11 (CCPA 1979), vacated, 444 U.S. 1028, aff'd sub
nom., Diamond v. Chakrabarty, 447 U.S. 303, 206 USPQ 193 (1980). The first
statutory class, process, is defined in 35 U.S.C. $ 100(b) and refers to
acts, while the last three classes, machine, manufacture and composition of
matter, refer to physical things; therefore, the general field of patentable
invention consists of new acts and new things. Id. The classes relevant to
this discussion are "process" and "machine." A "process" is equivalent to a
"method." Bergy 596 F.2d at 965, 201 USPQ at 364. The term "machine" is used
interchangeably with "apparatus." In re Prater, 415 F.2d 1393, 1395 n.11,
162 USPQ 541, 543 n.11 (CCPA 1969).
The question of whether a claimed invention satisfies the other conditions
for patentability is "wholly apart from whether the invention falls into a
category of statutory subject matter" (emphasis deleted). Diamond v. Diehr,
450 U.S. 175, 190, 209 USPQ 1, 9 (1981) (citing Bergy, 596 F.2d at 961, 201
USPQ at 361). As stated in Parker v. Flook, 437 U.S. 584, 593, 198 USPQ 193,
198-99 (1978):
The obligation to determine what type of discovery is sought to be
patented must precede the determination of whether that discovery
is, in fact, new [i.e., novel under $ 102] or obvious [$ 103].
See also In re Sarkar, 588 F.2d 1330, 1333 n.10, 200 USPQ 132, 137 n.10
(CCPA 1978) ("If the subject matter as claimed is subject to patenting,
i.e., if it falls within $ 101, it must them be examined for compliance with
$$ 102 and 103"). Legislative history indicates that Congress contemplated
that the subject matter provisions be given a broad construction and were
intended to "include anything under the sun that is made by man." Diamond v.
Chakrabarry, 447 U.S. at 309, 206 USPQ at 197. Any process, machine,
manufacture, or composition of matter constitutes statutory subject matter
unless it falls within a judicially determined exception to $ 101. In re
Pardo, 684 F.2d 912, 916, 214 USPQ 673, 677 (CCPA 1982). Exceptions include
laws of nature, physical phenomena and abstract ideas. Diehr, 450 U.S. at
185, 209 USPQ at 7, and cases cited therein. This analysis addresses whether
mathematical algorithms and computer programs are statutory subject matter.
II. Mathematical Algorithms
A. Mathematical algorithms per se are not a statutory "process" under $ 101
A mathematical algorithm is defined as a "procedure for solving a given type
of mathematical problem." Gottschalk v. Benson, 409 U.S. 63, 65, 175 USPQ
673, 674 (1972); Flook, 437 U.S. at 585 n.1. 198 USPQ at 195 n.1: Diehr, 450
U.S. at 186, 209 USPQ at 8. Mathematical algorithms are non- statutory
because they have been determined not to fall within the $ 101 statutory
class of a "process." Benson. "[A]n algorithm, or mathematical formula, is
like a law of nature, which cannot be the subject of a patent." Diehr, 450
U.S. at 186, 209 USPQ at 8. The exception applies only to mathematical
algorithms since any process is an " algorithm" in the sense that it is a
step-by-step procedure to arrive at a given result. In re Walter, 618 F.2d
758, 764 n.4, 205 USPQ 397, 405 n.4, (CCPA 1980); Pardo, 684 F.2d at 915,
214 USPQ at 676.
Although mathematical algorithms per se are nonstatutory, as stated in
Diehr, 450 U.S. at 187-88, 209 USPQ at 8-9:
[A] claim drawn to subject matter otherwise statutory does not become
nonstatutory simply because it uses a mathematical formula, computer
program, or digital computer. . . .
[I]n Parker v. Flook we stated that "a process is not unpatentable simply
because it contains a law of nature or a mathematical algorithm. " 437 U.S.
at 590. It is now commonplace that an application of a law of nature or
mathematical formula to a known structure or process may well be deserving
of patent protection. As Justice Stone explained four decades ago: "While a
scientific truth, or the mathematical expression of it, is not a patentable
invention, a novel and useful structure created with the aid and knowledge
of scientific truth may be."
Mackay Radio & Telegraph Co. v. Radio Corp. of America, 306 U.S. 86, 94
(1939). [Citations omitted]. The Supreme Court thus recognizes that
mathematical algorithms are "the basic tools of scientific and technological
work." Benson, 409 U.S. at 67, 175 USPQ at 674, and should not be the
subject of exclusive rights, whereas technological application of scientific
principles and mathematical algorithms furthers the constitutional purpose
of promoting "the Progress of . . . Useful arts." U.S. Const. art. I, $ 8.
It is also recognized that mathematical algorithms may be the most precise
way to described the invention.
Where claims involve mathematical algorithms, as stated in In re Abele, 684
F.2d 902, 907, 214 USPQ 687 (CCPA 1982): The goal is to answer the question
"What did applicants invent?" If the claimed invention is a mathematical
algorithm, it is improper subject matter for patent protection, whereas if
the claimed invention is an application of the algorithm, $ 101 will not bar
the grant of a patent.
The tests for determining whether claims containing mathematical algorithms
are statutory have gradually evolved in the courts since the Supreme Court's
decision in Benson in 1972.
B. Evolution of the two-part test for mathematical algorithm
-statutory subject matter
The proper legal analysis of mathematical algorithm
-statutory subject matter cases is the two-part test of In re Freeman, 573
F.2d 1237, 197 USPQ 464 (CCPA 1978), as modified by Walter and Abele. See In
re Meyer, 688 F.2d 789, 796, 215 USPQ 193, 198 (CCPA 1982) ("A more
comprehensive test for cases involving mathematical algorithms is set forth
In re Abele"). A review of the evolution of the analysis provides some
useful insights into the application of the test.
In Benson, the Supreme Court concluded that claims directed to a particular
algorithm for converting binary coded decimal numbers to binary numbers was
not statutory subject matter. The Supreme Court further concluded that any
patent issued on those claims "would wholly preempt the mathematical formula
and in practical effect would be a patent on the algorithm itself." 409 U.S.
at 72. 175 USPQ at 676. These two conclusions formed the basis for the
two-part analysis of the Court of Customs and Patent Appeals (CCPA) in
Freeman, 573 F.2d at 1245, 197 USPQ at 471:
First, it must be determined whether the claim directly or indirectly
recites an " algorithm" in the Benson sense of that term, for a claim which
fails even to recite an algorithm clearly cannot wholly preempt an
algorithm.
Second, the claim must be further analyzed to ascertain whether in its
entirety it wholly preempts that algorithm. In 1978, the Supreme Court held
in Flook that a claim need "not . . . cover every conceivable application of
the formula," to be nonstatutory, 437 U.S. at 586, 198 USPQ at 196. This
decision left undefined what constitutes statutory subject matter. In
Walter, the CCPA modified the second step of Freeman to require a more
positive approach to determining what is claimed, 618 F.2d at 767, 205 USPQ
at 407:
If it appears that the mathematical algorithm is implemented in a specific
manner to define structural relationships between the physical elements of
the claim (in apparatus claims) or to refine or limit claim steps (in
process claims), the claim being otherwise statutory, the claim passes
muster under $ 101. If, however, the mathematical algorithm is merely
presented and solved by the claimed invention, as was the case in Benson and
Flook, and is not applied in any manner to physical elements or process
steps, no amount of post-solution activity will render the claim statutory;
nor is it saved by a preamble merely reciting the field of use of the
mathematical algorithm.
The CCPA noted that while the second step of Freeman was "stated in terms of
preemption" it had consistently been applied "in the spirit of the foregoing
principles." 618 F.2d at 767, 205 USPQ at 407.
In Abele, the CCPA further modified the second part of the test to provide a
more comprehensive test. 684 F.2d at 906- 7, 214 USPQ at 686:
Appellants summarize the Walter test as setting forth two ends of a
spectrum: what is now clearly nonstatutory, i.e., claims in which an
algorithm is merely presented and solved by the claimed invention
(preemption), and what is clearly statutory, i.e., claims in which an
algorithm is implemented in a specific manner to define structural
relationships between the physical elements of the claim (in an apparatus
claim) or to refine or limit steps (in a process).
Appellants urge that the statement of the test in Walter fails to provide a
useful tool for analyzing claims in the "gray area" which falls between the
two ends of that spectrum. We agree that the board's understanding and
application of the Walter analysis justifies appellant's position. However,
the Walter analysis quoted above does not limit patentable subject matter
only to claims in which structural relationships or process steps are
defined, limited or refined by the application of the algorithm. Rather,
Walter should be read as requiring no more than 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. Thus, if the claim would be "otherwise
statutory," id., albeit inoperative or less useful without the algorithm,
the claim likewise presents statutory subject matter when the algorithm is
included.
This broad reading of Walter, we conclude, is in accord with the Supreme
Court decisions [holding "that a claim drawn to subject matter otherwise
statutory does not become nonstatutory simply because it uses a mathematical
formula, computer program, or digital computer." Diamond v. Diehr, 450 U.S.
at 187, 209 USPQ at 8].
The reason for the modification of the test was because, as noted in Abele,
684 F.2d at 909, 214 USPQ at 688:
The algorithm [in Abele] does not necessarily refine or limit the earlier
steps of production and detection as would be required to achieve the status
of patentable subject matter by the board's narrow reading of Walter.
The second test of Abele suggests that the determination of whether the
algorithm is "applied in any manner to physical element or process steps"
may be made by viewing the claims without the algorithm and determining
whether what remains is "otherwise statutory." This analysis focuses on
identifying the statutory process in the claim and is consistent with
previous cases such as Walter, 618 F.2d at 769, 205 USPQ at 409 (
"Examination of each claim demonstrates that each has no substance apart
from the calculations involved" ). The technique of viewing the claim
without the mathematical algorithm is not inconsistent with the requirement
that claims must be considered "as a whole" under $ 101.
The requirement that claims be considered "as a whole" arose out of the now
rejected "point of novelty" approach to statutory subject matter. Under the
"point of novelty" approach, if a claim considered without the nonstatutory
subject matter was unpatentable over the prior art (i.e., if the algorithm
was at the "point of novelty" of the claim), the claims were found to not
recite statutory subject matter. This approach was consistently rejected by
the CCPA. See In re Chatfield, 545 F.2d 152, 191 USPQ 730 (CCPA 1976),
cert. denied, 434 U.S. 875 (1977); In re Deutsch, 553 F.2d 689, 193 USPQ 645
(CCPA 1977); In re de Castelet, 562 F.2d 1236, 195 USPQ 439 (CCPA 1977);
Freeman; Sarkar; Walter. The point of novelty approach was finally put to
rest in Diehr, 450 U.S. at 188-89, 209 USPQ at 9:
In determining the eligibility of respondents' claimed process for patent
protection under $ 101, their claims must be considered as a whole. It is
inappropriate to dissect the claims into old and new elements and then to
ignore the presence of the old elements in the analysis. . . . The "novelty"
of any element or steps in a process, or even of the process itself, is of
no relevance in determining whether the subject matter of a claim falls
within the $ 101 categories of possibly patentable subject matter.
Under the second test of Abele, the claims are considered without the
algorithm to determine whether what remains is "otherwise statutory," not to
determine whether what remains is novel and nonobvious.
C. Application of the two-part test
1. Step 1 -- presence of a mathematical algorithm
a. Mathematical algorithm
A mathematical algorithm is a "procedure for solving a given type of
mathematical problem." In this sense, a mathematical algorithm refers "to
methods of calculation, mathematical formulas, and mathematical procedures
generally." Walter, 618 F.2d at 764-65 n.4, 205 USPQ at 405 n.4. "The type
of mathematical computation involved does not determine whether a procedure
is statutory or nonstatutory." In re Gelnovatch, 595 F.2d 32, 41.201 USPQ
136, 145 (CCPA 1979). A "claim for an improved method of calculation, even
when tied to a specific end use, is unpatentable subject matter under $
101." Flook, 437 U.S. at 595 n.18, 198 USPQ at 199 n.18. Mathematical
algorithms may represent scientific principles, laws of nature, or ideas or
mental processes for solving complex problems. See Meyer, 688 F.2d at
794-95, 215 USPQ at 197:
Scientific principles, such as the relationship between mass and energy [E =
mc n2], and laws of nature, such as the acceleration of gravity, namely a =
32 ft/sec. n2, can be represented in mathematical format. However, some
mathematical algorithms and formulae do not represent ideas or mental
processes and are simply logical vehicles for communicating possible
solutions to complex problems. See also Safe Flight Instrument Corp. v.
Sundstrand Data Control, Inc., 706 F.Supp. 1146, 10 USPQ2d 1733 (D.Del.
1989) (mathematical algorithm representing a natural phenomenon, windshear).
No distinction is made between mathematical algorithms invented by man, and
mathematical algorithms representing discoveries of scientific principles
and laws of nature which reveal a relationship that has always existed.
b. "Process" versus "appears" claims
Since mathematical algorithms have been determined not to fall within the $
101 statutory class of a "process," attempts have been made to circumvent
the nonstatutory subject matter rejection by drafting mathematical
algorithms as "machine" claims. The technique used is to draft the method
steps in terms of "means for" language permitted by 35 U.S.C. $ 112, sixth
paragraph. While such a claim is technically a "machine" or "apparatus"
claim, the courts have held that form of the claim does not control whether
the subject matter is statutory. See In re Maucorps, 609 F.2d 481, 485, 203
USPQ 812, 815-16 (CCPA 1979):
Labels are not determinative $ 101 inquiries. "Benson applies equally
whether an invention is claimed as an apparatus or process, because the form
of the claim is often an exercise in drafting." In re Johnson, 589 F.2d
1070, 1077, 200 USPQ 199, 206 ([CCPA] 1978). "Though a claim expressed in
'means for (functional) terms [under 35 U.S.C. $ 112, sixth paragraph] is
said to be an apparatus claim, the subject matter as a whole of that claim
may be indistinguishable from that of a method claim drawn to the steps
performed by the 'means,'" In re Freeman, 573 F.2d at 1247, 197 USPQ at 472.
Moreover, that the claimed computing system may be a "machine" within "the
ordinary sense of the word," as appellant argues, is irrelevant. The holding
in Benson "forecloses a purely literal reading of $ 101."
The test for determining whether "means for" apparatus claims should be
treated as method claims is stated in Walter, 618 F.2d at 768, 205 USPQ at
408:
If the functionally-defined disclosed means and their equivalents are so
broad that they encompass any and every means for performing the recited
functions, the apparatus claim is an attempt to exalt form over substance
since the claim is really to the method or series of functions itself . . .
. In such cases the burden must be placed on the applicant to demonstrate
that the claims are truly drawn to specific apparatus distinct from other
apparatus capable of performing the identical functions.
If this burden has not been discharged, the apparatus claim will be treated
as if it were drawn to the method or process which encompasses all of the
claimed "means." See In re Maucorps, 609 F.2d at 485, 203 USPQ at 815-816:
In re Johnson, 589 F.2d at 1077, 200 USPQ at 206: In re Freeman, 573 F.2d at
1247, 197 USPQ at 472. The statutory nature of the claim under $ 101 will
then depend on whether the corresponding method is statutory.
See also Meyer, 688 F.2d at 795 n.3, 215 USPQ at 198 n.3; Abele, 684 F.2d at
909, 214 USPQ at 688; Pardo. 684 F.2d at 916 n.6. 214 USPQ at 677 n.6;
Arshal v. United States, 621 F.2d 421, 427-28, 208 USPQ 397, 404 (Ct. Cl.
1980), cert. denied, 449 U.S. 1077 (1981), reh'g denied, 450 U.S. 1050
(1981). In Maucorps, the limitation of various "means" in claim 1 to include
certain "electric circuits" did not prevent the claim from being treated as
a method. A claim is not presumed to be statutory simply because it is in
apparatus form.
c. Form of the mathematical algorithm
The first step of the analysis is to determine whether the claim directly or
indirectly recites a mathematical algorithm. A mathematical algorithm can
appear in many forms. As stated in Freeman, 573 F.2d at 1246, 197 USPQ at
471:
The manner in which a claim recites a mathematical algorithm may vary
considerably. In some claims, a formula or equation may be expressed in
traditional mathematical symbols so as to be immediately recognizable as a
mathematical algorithm. See e.g., In re Richman, 563 F.2d 1026, 195 USPQ
340 ([CCPA] 1977); In re Flook, 559 F.2d 21, 195 USPQ 9([CCPA] 1977), cert.
granted such nom, Parker v. Flook, [437 U.S. 584] (1978). Other claims may
use prose to express a mathematical computation or to indirectly recite a
mathematical equation or formula by means of a prose equivalent therefor.
See, e.g., In re de Castelet, supra (claims 6 and 7); In re Waldhaum, 559
F.2d 611, 194 USPQ 465 ([CCPA] 1977). A claim which substitutes, for a
mathematical formula in algebraic form, "words which mean the same thing,"
nonetheless recites an algorithm in the Benson sense. In re Richman, supra
563 F.2d at 1030, 195 USPQ at 344. Indeed, the claims at issue on Benson did
not contain a formula equation expressed in mathematical symbols.
Claims which include mathematical formulas or calculations expressed in
mathematical symbols clearly include a mathematical algorithm. Mathematical
algorithms in prose form may be expressed as literal translations of the
mathematical algorithm (e.g., substituting the expression "division" or
"taking the ratio" for a diversion sign) or may be expressed in words which
indicate the mathematical algorithm. See Safe Flight Instrument, 706 F.Supp.
at 1148, 10 USPQ at 1734 (subtracting); Abele, 684 F.2d at 908 n. 8, 214
USPQ at 687 n.8 ("The algorithm, calculating the difference, is defined in
the specification as a Gaussian weighting function"): In re Taner, 681 F.2d
787, 790, 214 USPQ 678, 681 (CCPA 1982) (summing); In re Johnson, 589 F.2d
1070, 1079, 200 USPQ 199, 208 (CCPA (1978) ("'computing' connotes the
execution of the one of a sequence of mathematical operations"); In re
Waldbaum, 559 F.2d 611, 194 USPQ 465 (CCPA 1977) (method of claim 1 "to
count" the number of busy lines "solves a mathematical problem, to wit,
counting a number of busy lines in a telephone system." In re Bradley, 600
F.2d 807, 810 n. 4, 202 USPQ 480, 484 n.4 (CCPA 1979), aff'd by an equally
divided court sub nom.
Diamond v. Bradley, 450 U.S. 381, 209 USPQ 97 (1981)).
It is not always possible to determine by inspection of the claim whether it
indirectly recites a mathematical algorithm; in such instances the analysis
"requires careful interpretation of each claim in the light of its
supporting disclosure." Johnson, 589 F.2d at 1079, 200 USPQ at 208. See also
id. at 1078-79, 200 USPQ at 208 ("the flow diagrams which form part of the
specification disclose explicit mathematical equations which are to be used
in conjunction with each of these [claimed] steps [of 'determining' or
'correlating']"); Waldbaum, 559 F.2d 611, 194 USPQ 465 ("series of steps for
manipulating binary numbers within a procedure for calculating the number of
binary 1's and 0's present" was considered a mathematical algorithm.
Gelnovatch, 595 F.2d at 39, 2001 USPQ at 143); In re Sherwood, 613 F.2d 809,
818, 204 USPQ 537, 545 (CCPA 1980), cert. denied, 450 U.S. 994 (1981)
("claims must be said to include the indirect recitation of a mathematical
equation"); Meyer, 688 F.2d at 795, 215 USPQ at 198 (claims indirectly
"recite a mathematical algorithm, which represents a mental process that a
neurologist should follow").
2. Step 2 -- is the mathematical algorithm "applied in any manner to
physical elements or process steps?" The second test is to determine whether
the mathematical algorithm is "applied in any manner to physical elements or
process steps." The guideline for the analysis should be the CCPA's
suggestion in Abele to view the claim without the mathematical algorithm to
determine whether what remains is "otherwise statutory"; if it is, it does
not become nonstatutory simply because it uses a mathematical algorithm. It
is recognized that "[t]he line between a patentable 'process' and an
unpatentable 'principle' is not always clear." Flook, 437 U.S. at 589, 198
USPQ at 197.
There are no definitive "tests for determining whether a claim positively
recites statutory subject matter." Meyer, 688 F.2d at 796 n.4, 215 USPQ at
198 n.4. Nevertheless, some useful guidelines may be synthesized out of the
court decisions.
a. Post-solution activity
If the only limitation aside from the mathematical algorithm is
insignificant or non-essential "post-solution activity," the claimed subject
matter is nonstatutory, Flook, 437 U.S. at 5900, 198 USPQ at 197:
The notion that post-solution activity . . . can transform an unpatentable
principle into a patentable process exalts form over substance. A competent
draftsman could attach some form of post-solution activity to almost any
mathematical formula; the Pythagorean theorem would not have been
patentable, or partially patentable, because a patent application contained
a final step indicating that the formula, when solved, could be usefully
applied to existing surveying techniques.
Insignificant post-solution activity by itself is insufficient to constitute
a statutory process. In Flook, the final step of adjusting an alarm limit
was not sufficient. See also Safe Flight (final step of "means for
processing and windshear signal to provide an indication representing the
magnitude thereof" not sufficient); Abele, 684 F.2d at 909, 214 USPQ at 688
(final step of display; "that the result is displayed as a shade of gray
rather than as simply a number provides no greater or better information,
considering the broad range of applications encompassed by the claims");
Walter, 618 F.2d at 770, 205 USPQ at 4009 (final step in dependent claim of
magnetic recording: "If $ 101 could be satisfied by the mere recordation of
the results of a nonstatutory process on some record medium, even the most
unskilled patent draftsman could provide for such a step"); Gelnovatch, 595
F.2d at 41 n.7, 201 USPQ at 145 n.7 (final step of storing outputs: "each of
the steps of the claimed process, except perhaps the final step of equating
the process outputs to the values of the last set of process inputs,
directly or indirectly recites a mathematical computation"); Sarkar, 588
F.2d at 1332 n.6, 200 USPQ at 136 n.6 (final step of constructing an
obstruction at a location determined by a mathematical model: "Sarkar no
longer relies upon bridge of dam construction as post-solution activity
steps effective to bring his process within $ 101"); de Castelet, 562 F.2d
at 1244, 195 USPQ at 446 (final step of transmitting; "That the computer is
instructed to transmit electrical signals, representing the result of its
calculations . . . does not transform the claim into one for a process
merely using an algorithm" ).
The absence of post-solution activity to the fact that any post-solution
activity may be trivial is only one factor to be considered. On one hand, as
stated in Walter, 618 F.2d at 767-68, 205 USPQ at 407: if the end-product of
a claimed invention is a pure number, as in Benson and Flook, the invention
is nonstatutory regardless of any post-solution activity which makes it
available for use by a person or machine for other purposes.
On the other hand, as stated in Abele, 684 F.2d at 908 n.9, 214 USPQ at 687
n.9:
"the fact that [the] equation is the final step is not determinative of the
section 101 issue." In re Richman, 563 F.2d at 1030, 195 USPQ at 343.
Accord, In re Taner, 681 F.2d 787 ([CCPA] (1982), overruling In re
Christensen, 478 F.2d 1392, 178 USPQ 35 ([CCPA] 1973). The particular order
of the steps should not be determinative of the statutory subject matter
inquiry.
b. Field of use limitations
A mathematical algorithm is not made statutory by "attempting to limit the
use of the formula to a particular technological environment." Diehr, 450
U.S. at 191, 209 USPQ at 10. Thus, "field of use" or "end use" limitations
in the claim preamble are insufficient to constitute a statutory process.
This is consistent with the usual treatment of preambles as merely setting
forth the environment. See Flook (the preamble while limiting the
application of the claimed method to "a process comprising the catalytic
chemical conversion of hydrocarbons" did not serve to render the method
statutory); Walter, 618 F.2d at 769, 205 USPQ at 409 ("Although the claim
preambles relate the claimed invention to the art of seismic prospecting,
the claims themselves are not drawn to methods of or apparatus for seismic
prospecting"); de Castelet, 562 F.2d at 1244 n.6. 195 USPQ at 446 n.6 ("The
potential for misconstruction of preamble language requires that compelling
reason exist before that language may be given weight"). Compare Waldbaum,
559 F.2d at 616 n.6. 194 USPQ 469 n.6 (portion of preambles referred to in
method portion of claims "are necessary for completeness of the claims and
are proper limitations thereto").
c. Data-gathering steps
If the only limitations in the claims in addition to the mathematical
algorithm are data-gathering steps which "merely determine values for the
variables used in the mathematical formulae used in making the
calculations." Such antecedent steps are insufficient to change a
nonstatutory method of calculation into a statutory process. See In re
Richman, 563 F.2d at 1030. 195 USPQ at 343; Sarkar. 588 F.2d at 1335. 200
USPQ at 139 ("If the steps of gathering and substituting values were alone
sufficient, every mathematical equation, formula, or algorithm having any
practical use would be per se subject to patenting as a 'process' under $
101"): Gelnovatch, 595 F.2d at 41 n.7. 201 USPQ at 145 n.7 ("claimed step of
perturbing the values of a set of process inputs (step 3), in addition to
being a mathematical operation, appears to be a data-gathering step"). Where
the claim "presents data gathering steps not dictated by the algorithm but
by other limitations which require certain antecedent steps" the claim may
present statutory subject matter. Abele, 684 F.2d at 908, 214 USPQ at 687.
d. Transformation of something physical
In determining whether the claim recites a statutory process or a
nonstatutory mathematical algorithm, it is useful to analyze whether there
is transformation of something physical into a different form. One
distinction is made between transformation of physical "signals" from one
physical state to a different physical state, a statutory process in the
electrical arts, and mere mathematical manipulation of "data" which, by
itself, is not a statutory process. Compare Tuner (conversion of
"substantially spherical seismic signals" into "a form representing the
earth's response to cylindrical or plane waves" was statutory process):
Sherwood 613 F.2d at 819, 204 USPQ at 546 (conversion of
amplitude-versus-time seismic traces into amplitude-versus-depth seismic
traces was statutory process because it "converts one physical thing into
another physical thing just as any other electrical circuitry would do");
and Johnson (technique for removing unwanted noise from a seismic trace was
statutory process); with Walter, 618 F.2d at 768, 770, 205 USPQ at 407, 409
(if "the claimed invention produces a physical thing . . . the fact that it
is represented in numerical form does not render the claim nonstatutory" but
finding that the "signals" claimed "may represent either physical quantities
or abstract quantities" and thus were to the algorithm itself and not a
particular application); Richman (method of calculating airborne radar
boresight correction angle from 'a plurality of signal sets" not statutory);
Gelnovatch, 595 F.2d at 42, 201 USPQ at 145 (where "the claims solely recite
a method whereby a set of numbers is computed from a different set of
numbers by merely performing a series of mathematical computations, the
claims do not set forth a statutory process"); and Benson (conversion of
binary coded decimal numbers into pure binary numbers not statutory). It is
manifest that the statutory nature of the subject matter does not depend on
the labels "signals" or "data."
e. Structural limitations in process claims
Another issue is the effect of structural limitations in method claims.
While structural limitations in method claims are not improper, they are
usually not entitled to patentable weight unless they somehow affect or form
an essential part of the process. See Benson, 409 U.S. at 73, 175 USPQ at
677 (claim 8 recited use of a "reentrant shift register"): Waldbaum, 559
F.2d at 66, 194 USPQ at 469 (machine limitations in data processor method
claims); de Castelet, 562 F.2d at 1244, 195 USPQ at 47 ("Claims to
nonstatutory processes do not automatically and invariably become patentable
upon incorporation of reference to apparatus"). The related problem of
specific structural language in apparatus claims has been treated. supra, in
section II.C.1.b.
D. Examples
1. Diamond v. Diehr
The following claim was held to recite statutory subject matter.
1. A method of operating a rubber-molding press for precision molded
compound 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 compounded 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);
respectively calculating in the computer, at frequent intervals
during each cure, the Arrhenius equation for reaction time during
the cure, which is ln v=CZ+x, where v is the total required cure
time. repetitively comparing in the computer at said 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 equivalence.
Step 1 The claim contains an equation for controlling the in-mold time: In
v=CZ + x.
Step 2 The claimed subject matter is statutory because it recites an
"otherwise statutory" process in addition to the mathematical algorithm. As
stated in Abele, 684 F.2d at 907. 214 USPQ at 686:
In Diehr, were the claims to be read without the algorithm, the process
would still be a process for curing rubber, although it might not work as
well since the in-mold time would not be as accurately controlled. The steps
in the process, 450 U.S. at 187, 209 USPQ at 8: include installing rubber in
a press, closing the mold, constantly determining the temperature of the
mold, constantly recalculating the appropriate cure time through the use of
the formula and a digital computer, and automatically opening the press at
the proper time. The statutory nature of the claim is not based on the post-
solution activity of opening the press, but on the application of the
mathematical algorithm to the whole process.
2. Parker v. Flook
The following claim in Flook was held to recite nonstatutory subject matter.
1. A method for updating the value of at least one alarm limit on at least
one process variable involved in a process comprising the catalytic chemical
conversion of hydrocarbons wherein said alarm limit has a current value of
Bo + K wherein Bo is the current alarm base and K is a predetermined alarm
offset which comprises:
(1) determining the present value of said process variable said
present value being defined as PVL:
(2) determining a new alarm base B1 using the following equation:
B1 = Bo(1.0 - F) + PVL(F)
where F is a predetermined number greater than zero and less than
1.0:
(3) determining an updated alarm limit which is defined as B1 + K:
and thereafter
(4) adjusting said alarm limit to said updated alarm limit value.
Step 1 The claim contains a mathematical algorithm comprising determining a
new alarm base in step (2) and computing an "alarm limit" in step (3).
Step 2 When viewed without the steps of the mathematical algorithm, steps
(2) and (3), the only limitations remaining are the preamble limitation
restricting the field of use to "a process comprising the catalytic chemical
conversion of hydrocarbons;" the data- gathering step of step (1); and the
post-solution step of step (4). None of these limitations comprises an
"otherwise statutory" process. The claim seeks to protect a method for
computing an "alarm limit" rather than the application of the computation
within an otherwise statutory process.
3. In re Abele
In Abele, claim 5 was held to recite nonstatutory subject matter under $ 101
whereas dependent claim 6 was statutory.
5. A method of displaying data in a field comprising the steps of
calculating the difference between the local value of the data at a data
point in the field and the average value of the data in a region of the
field which surrounds said point for each point in said field, and
displaying the value of said difference as a signed gray scale at a point in
a picture which corresponds to said data point.
7. The method of claim 5 wherein said data is X-ray attenuation data
produced in a two dimensional field by a computed tomography scanner. Step 1
Claim 5 contains a mathematical algorithm, "calculating the difference,"
which is defined in the specification as a Gaussian weighting function. Step
2 When claim 5 is viewed without the mathematical algorithm, the only
remaining limitation is the post- solution activity of displaying the
result. The display by itself did not constitute an "otherwise statutory"
process. The court held that "the algorithm is neither explicitly nor
implicitly applied to any certain process." 684 F.2d at 909, 214 USPQ at
688. However, when dependent claim 6 is added to the limitations of claim 5,
684 F.2d at 908, 214 USPQ at 687-88:
Were we to view the claim absent the algorithm, the production, detection
and display steps would still be present and would result in a conventional
CAT-scan process. . . . [W]e view the production, detection, and display
steps as manifestly statutory subject matter and are not swayed from this
conclusion by the presence of an algorithm in the claimed method.
III. Computer Programs
A. "Computer programs" versus "computer processes"
A "process" or " algorithm" is a step-by-step procedure to arrive at a given
result. In the patent area, a "computer process" or "computer algorithm" is
a process, i.e., a series of steps, which is performed by a computer. A
"[computer] program is a sequence of coded instructions for a digital
computer. Benson, 409 U.S. at 65. 175 USPQ at 674. Computer programs are
equivalently known as "software." Unfortunately for discussion in this area,
"[b]oth the series of steps performed by a computer, and the software
directing those steps, have acquired the name "computer program."
Gelnovatch, 595 F.2d at 45 n.5, 201 USPQ at 148 n.5 (Markey, C.J.,
dissenting). What is sought to be protected by patent is the underlying
process. As stated in Gelnovatch, 595 F.2d at 44, 201 USPQ at 147: Confusion
may be avoided if it be realized that what is at issue is not the "program,"
i.e., the software, but the process steps which the software directs the
computer to perform.
See, e.g., Maucorps, 609 F.2d at 483, 203 USPQ at 814 ("The [claimed]
invention is implemented via a computer program written in FORTRAN IV,
either built into the calculating machine, or loaded into a general purpose
computer").
B. Statutory nature of computer processes
1. The Supreme Court has not ruled on the patentability of computer
programs.
The Supreme Court has not ruled on whether computer process are per se
statutory or nonstatutory. The decisions in Benson, Flook and Diehr all
dealt with claims viewed as mathematical algorithms. In Benson and Diehr,
the claims contained mathematical algorithms implemented by a computer.
In Benson, the Court held that the claims preempted the use of the
mathematical algorithm, but did not hold that "any program servicing a
computer" would be nonstatutory. In Diehr, the Court held that the claims
otherwise defined a statutory process for curing rubber, and that the
inclusion of a mathematical algorithm or computer program did not make claim
nonstatutory. The claim in Flook did not involve a computer process.
In Dann v. Johnson, 425 U.S. 219, 189 USPQ 257 (1976), rev'g on other
grounds, In re Johnson, 502 F.2d 765, 183 USPQ 172 (CCPA 1974), which
involved a "machine system for automatic record-keeping of bank checks and
deposits," the Court declined to discuss the $ 101 issue of the general
patentability of computer programs, 425 U.S. at 220, 189 USPQ at 258:
We find no need to treat that question in this case, however, because we
conclude that in any event respondent's system is unpatentable on grounds of
obviousness. 35 U.S.C. $ 103.
In Diamond v. Bradley, an equally divided Supreme Court affirmed the CCPA's
decision in Bradley. The claims were directed to computer "firmware," which
refers to microinstructions permanently embodied in hardware elements, and
not to a computer application or process. The CCPA found that the claims
literally recited a machine and that, in applying the two-part test of
Freeman, the claims did not recite a mathematical algorithm.
2. The CCPA has held that computer processes are statutory unless they fall
within a judicially determined exemption. In Pardo, the most recent CCPA
case on computer processes, the CCPA stated that, 684 F.2d at 916, 214 USPQ
at 677: any process, machine, manufacture, or composition of matter
constitutes statutory subject matter unless it falls within a judicially
determined exception to section 101. The major (and perhaps only) exception
in the area of computer processes is the mathematical algorithm. Although
not binding precedent on the Federal Circuit, the district court in Paine,
Webber, Jackson & Curtis, Inc. v. Merill, Lynch, Lynch, Pierce, Fenner &
Smith, 564 F.Supp. 1358, 1367, 218 USPQ 212, 218 (D. Del. 1983) stated:
The CCPA [has] . . . held that a computer algorithm, as opposed to a
mathematical algorithm, is patentable subject matter.
If a computer process claim does not contain a mathematical
algorithm in the Benson sense, the second step of the
Freeman-Walter-Abele test is not reached, and the claimed
subject matter will usually be statutory.
The traditional approach by the CCPA to the PTO's rejection
of computer processes as nonstatutory subject matter has
been to apply the two-part test for mathematical algorithms
and to find statutory subject matter if the claims do not
recite a mathematical algorithm. See Pardo, 684 F.2d at 916,
214 USPQ at 676 (process for converting source program into
object program: "we are unable to find any mathematical
formula, calculation, or algorithm either directly or
indirectly recited in the claimed steps of examining,
compiling, storing, and executing"); In re Toma, 575 F.2d
872, 877, 197 USPQ 852, 856 (CCPA 1978) (process for
translating a source natural language, e.g., Russian, to a
target natural language, e.g., English: "[we] are unable to
find any direct or indirect recitation of a procedure for
solving a mathematical problem"); In re Phillips, 608 F.2d
879, 883, 203 USPQ 971, 975 (CCPA 1979) (process for
preparing architectural specifications: "Our analysis of the
claims on appeal reveals no recitation, directly or
indirectly, of an algorithm in the Benson and Flook sense");
Freeman, 573 F.2d at 1246, 197 USPQ at 471 ("The method
claims here at issue do not recite process steps which are
themselves mathematical calculations, formulae, or
equations"); Deutsch, 553 F.2d 689, 692, 193 USPQ 645, 648
(CCPA 1977) (method of operating a system of manufacturing
plants: "Nothing in the methods claimed by Deutsch preempts
a mathematical formula, an algorithm, or any specific
computer program"); Chatfield, 545 F.2d at 158, 191 USPQ at
736 (method of reassigning priorities within a computer.
"[the] independent claims contain neither a mathematical
formula nor a mathematical algorithm" ).
If the computer process is found to contain a mathematical algorithm, it
must then pass the second part of the Freeman- Walter-Abele test for
statutory subject matter. See. e.g., Sherwood; Maucorps; Gelnovatch.
Arguably, other exceptions such as "methods of doing business" and "mental
steps" may be raised if a claim is not a true computer process but merely
recites that an otherwise nonstatutory process is performed on a computer.
de Castelet, 562 F.2d at 1244, 195 USPQ at 447 ("Claims to nonstatutory
processes do not automatically and invariable become patentable upon
incorporation of reference to apparatus"). These would appear to be
exceptions with very narrow application to claims which are not limited to
implementation by a machine. For example, while a "method of doing business"
per se is not statutory subject matter, "a method of operation on a computer
to effectuate a business activity" has been held to be statutory subject
matter. Paine, Webber v. Merrill Lynch, 564 F.Supp. at 1369, 218 USPQ at
220. See also Deutsch, 553 F.2d at 692 n.5. 193 USPQ at 648 n.5 (claims were
not a method of doing business because "[t]hey do not merely facilitate
business dealings"); Johnston, rev'd on other grounds. Dann v. Johnston
(apparatus claims directed to system for automatic record-keeping of bank
checks and deposits did not cover a method of doing business). Similarly,
machine or computer implementation of "mental steps" is statutory subject
matter. Prater: In re Bernhart, 417 F.2d 1395, 163 USPQ 611 (CCPA 1969); In
re Musgrave, 431 F.2d 882, 167 USPQ 280 (CCPA 1970). See also Toma (computer
implemented method for translation of natural languages is statutory).
Chronological Order Case List
In re Prater, 415 F.2d 1393, 162 USPQ 541 (CCPA 1969)
In re Bernhart, 417 F.2d 1395, 163 USPQ 611 (CCPA 1969)
In re Musgrave, 431 F.2d 882, 167 USPQ 280 (CCPA 1970)
Gottschalk v. Benson, 409 U.S. 63, 175 USPQ 673 (1972)
In re Christensen, 478 F.2d 1392, 178 USPQ 35 (CCPA 1973)
Dann v. Johnston, 425 U.S. 219, 189 USPQ 257 (1976), rev'd on other grounds.
In re Johnston, 502 F.2d 765, 183 USPQ 172 (CCPA 1974)
In re Noll, 545 F.2d 141, 191 USPQ 721 (CCPA 1976), cert, denied, 434 U.S.
875, 195 USPQ 465 (1977)
In re Chattield, 545 F.2d 152, 191 USPQ 730 (CCPA 1976). cert. denied, 434
U.S. 875, 195 USPQ 465 (1977)
In re Deutsch, 553 F.2d 689, 193 USPQ 645 (CCPA 1977)
In re Waldbaum, 559 F.2d 611, 194 USPQ 465 (CCPA 1977)
In re Richman, 563 F.2d 1026, 195 USPQ 340 (CCPA 1977)
In re de Castelet, 562 F.2d 1236, 195 USPQ 439 (CCPA 1977)
In re Freeman, 573 F.2d 1237, 197 USPQ 464 (CCPA 1978)
In re Toma, 575 F.2d 872, 197 USPQ 852 (CCPA 1978)
Parker v. Flook, 437 U.S. 584, 198 USPQ 193 (1978)
In re Sarkar, 588 F.2d 1330, 200 USPQ 132 (CCPA 1978)
Hirschfeld v. Banner, 462 F.Supp. 135, 200 USPQ 276 (D.D.C. 198), aff'd
without opinion, 615 F.2d 1368 (D.C. Cir. 1980). cert. denied, 450 U.S.
994, 210 USPQ 776 (1981)
In re Gelnovatch, 595 F.2d 32, 201 USPQ 136 (CCPA 1979)
In re Maucorps, 609 F.2d 481, 203 USPQ 812 (CCPA 1979)
In re Phillips, 608 F.2d 879, 203 USPQ 971 (CCPA 1979)
In re Sherwood, 613 F.2d 809, 204 USPQ 537 (CCPA 1980). cert. denied, 450
U.S. 994, 210 USPQ 776 (1981)
In re Walter, 618 F.2d 758, 205 USPQ 397 (CCPA 1980)
Arshal v. United States, 621 F.2d 421, 208 USPQ 397 (Ct. Cl.
1980), cert. denied, 449 U.S. 1088 (1981). reh'g denied, 450
U.S. 1050 (1981)
Diamond v. Diehr, 450 U.S. 175, 209 USPQ 1 (1981)
Diamond v. Bradley, 45 U.S. 381, 209 USPQ 97 (1981). aff'g
by an equals divided Court. In re Bradley, 600 F.2d 807, 202
USPQ 480 (CCPA 1979)
In re Pardo, 684 F.2d 912, 214 USPQ 673 (CCPA 1982)
In re Taner, 681 F.2d 787, 214 USPQ 678 (CCPA 1982)
In re Abele, 684 F.2d 902, 214 USPQ 682 (CCPA 1982)
In re Meyer, 688 F.2d 789, 215 USPQ 193 (CCPA 1982)
Paine, Webber, Jackson & Curtis, Inc. v. Merrill Lynch,
Pierce, Fenner & Smith, 564 F.Supp. 1358, 218 USPQ 212 (D. Del. 1983)
Safe Flight Instrument Corp. v. Sundstrand Data Control Inc., 706 F.Supp.
1146, 10 USPQ2d 1733 (D. Del. 1989)