Means-plus-function clauses in patent claims: a tortuous path.

Although Continental Paper Bag was decided in 1908, it was not forgotten forty years later. After reaching its holding in Halliburton, the Court stated that its conclusion was not in conflict with its earlier decision in Continental Paper Bag because the claims at issue in Continental "structurally described the physical and operating relationship of all the crucial parts of the novel combination." (35) Thus, the Halliburton Court ostensibly did not overrule Continental Paper Bag, which had held that a means-plus-function clause at the precise point of novelty did not render the claims invalid. (36) Instead, the Court distinguished Continental Paper Bag on the basis that the means-plus-function clause in Continental was contained in claims that properly defined the relationship between the various claim elements. (37)

In light of the courts' less-than-favorable attitude toward patents in the 1940's, however, there was concern that all claims having one or more means-plus-function clauses would be held invalid under the ruling of Halliburton. (38) In 1952, following the impetus of the patent bar, Congress voted in favor of the Continental Paper Bag approach by adopting 35 U.S.C. [section] 112, paragraph 6. (39)

IV. LEGISLATIVE HISTORY

The legislative history concerning [section] 112, paragraph 6, is sparse, but it shows that the initial draft of this section first appeared as a proposal in December 1950, (40) shortly after the Supreme Court's landmark opinion on the doctrine of equivalents in Graver Tank. (41) In subsequent hearings on the patent bill, in which this section appeared in essentially its present state, (42) there was recognition that the purpose of the section was to offset the much criticized Halliburton decision. (43) However, there was opposition to this section by the Department of Justice because it "introduce[d] into the statute for the first time the controversial doctrine of equivalents." (44)

Others favored the section, but they agreed that this new section would serve to establish a statutory foothold for the doctrine of equivalents. For example, a paper by Representative Bryson, Chairman of the Patent and Trademark Subcommittee handling the drafts of the Patent Act of 1952, stated:

I should like to say a word on the provision in the bill for

functional claiming. The subcommittee realizes that this will

permit combination claims to be expressed functionally at the

point of novelty. This provision in reality will give statutory

sanction to combination claiming as it was understood before

the Halliburton decision.... This provision also gives recognition

to the existence of the doctrine of equivalents.

An article by James L. Harris, Counsel to the Patent, Trademark and Copyright Subcommittee that prepared the drafts of the 1952 Act, similarly stated that "[t]o provide for the proper interpretation of the claims commensurate with the invention, the doctrine of equivalents is specifically mentioned in the section." (46)

Thus, [section] 112, paragraph 6, came into being very shortly after the Graver Tank opinion had reaffirmed the doctrine of equivalents, which was the only form of equivalence in existence at the time. Additionally, the section sought to solve the Halliburton problem by relying on this doctrine. (47) In 1997, even the Supreme Court attributed this role to [section] 112, paragraph 6, stating, "This is an application of the doctrine of equivalents in a restrictive role, narrowing the application of broad literal claim elements." (48)

V. LIFE UNDER TWO DIFFERENT STANDARDS

It is difficult to assess the practical effect of the judicial creation of two different standards of equivalence, one for [section] 112, paragraph 6, and a different one under the traditional doctrine of equivalents. Actually, [section] 112, paragraph 6, has been construed to bring into play two standards, one for literal infringement and another if literal infringement is not established. (49) Also, the doctrine of equivalents rather than [section] 112, paragraph 6, equivalence applies in situations where the accused device does not employ precisely the same function claimed in the patent. (50) One obvious effect of this state of the law is confusion.

It is often a metaphysical exercise to determine whether two elements are "equivalent" in patent law. This is doubly perplexing when there are two different equivalence standards. Moreover, when both standards may apply seriatim to a means-plus-function clause, the fact finder is truly in Wonderland.

The genesis of two different equivalence standards appears to be the Federal Circuit opinion in D.M.I., Inc. v. Deere & Co., (51) where the court stated:

Thus the word "equivalent" in [section] 112 should not be confused,

as it apparently was here, with the "doctrine of equivalents." In

applying the doctrine of equivalents, the fact finder must

determine the range of equivalents to which the claimed

invention is entitled, in light of the prosecution history, the

pioneer-non-pioneer status of the invention, and the prior art. It

must then be determined whether the entirety of the accused

device or process is so "substantially the same thing, used in

substantially the same way, to achieve substantially the same

result" as to fall within that range.... In applying the "means

plus function" paragraph of [section] 112, however, the sole

question is whether the single means in the accused device which

performs the function stated in the claim is the same as or an

equivalent of the corresponding structure described in the

patentee's specification as performing that function. (52)

This passage does not identify the factors to be considered in assessing whether the structure in the accused device is equivalent to the corresponding structure under [section] 112, paragraph 6. It does note, however, that this equivalence operates differently from the traditional doctrine of equivalents because the latter is applied to "the entirety of the accused device or process." (53) The Supreme Court had no difficulty, however, in applying the doctrine of equivalents to an individual means in Continental Paper Bag. (54) Also, more recently, the Supreme Court eliminated this difference by holding that the doctrine of equivalents must be applied on an element-by-element basis. (55)

D.M.I. was followed by Palumbo v. Don-Joy Co., (56) where the Federal Circuit noted the proximity in time of the 1952 Act to the Supreme Court's doctrine of equivalents opinion in Graver Tank. (57) The court also noted that both of the Federal Circuit's predecessor courts had applied the Graver Tank concept of equivalents to means-plus-function clauses under [section] 112, paragraph 6, (58) which should have compelled a similar result in the Federal Circuit, absent an en banc ruling to the contrary. (59) The court found, however, that [section] 112, paragraph 6, equivalence differs from the doctrine of equivalents in that [section] 112, paragraph 6, equivalence may lead only to a finding of literal infringement. (60) As previously noted, no support for this reading can be found in the statute.

Thereafter, in Valmont Industries, Inc. v. Reinke Manufacturing Co., (61) the Federal Circuit stated that [section] 112, paragraph 6, and the doctrine of equivalents "have separate origins and purposes," (62) but there is no explanation why the difference in origin and purpose calls for a new mode of equivalence. Nor is there any apparent reason why this should be the case. The court also stated, perhaps as an illustration of the different purposes, that [section] 112, paragraph 6, limits a claim, while the doctrine of equivalents expands it. (63) However, as the Supreme Court discussed in Graver Tank and mentioned in Warner-Jenkinson, these different purposes are both roles of the doctrine of equivalents. (64)

The court followed the same path in Alpex Computer Corp. v. Nintendo, (65) stating that the two forms of equivalence are characterized by separate origins, purposes and applications. (66) Again, no effort was made to demonstrate why these factors might compel a new form of equivalence, rather than the traditional doctrine of equivalents. The only further explanation in Alpex is an observation that [section] 112, paragraph 6, involves a comparison to the structure that corresponds to the claimed means, while the doctrine of equivalents involves a comparison of the entire claim with the accused device. (67) As noted, this difference ignores the Supreme Court's ruling in Continental and has clearly been eliminated by the Supreme Court's ruling in Warner-Jenkinson. (68)

Having embarked on a path of two different equivalence standards, it became necessary to determine not only the meaning of each standard and how the standards differ, but whether the traditional doctrine of equivalents always applies when [section] 112, paragraph 6, equivalence fails. For a statute that was heralded as being clear on its face, it may seem strange that the profession had no idea what tack the courts would take on these basic questions for some forty years. Nor has the tack been a consistent one.