United States: A Lifeline For The Drafters And Interpreters Of Patent Claims Or A Trap For The Unwary?
35 U.S.C. §112, 6

35 U.S.C. §112, 6 reads:

An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.

This provision has existed in United States patent law since the Patent Act of July 19, 1952 became effective, early in 1953, but the scope of its usefulness to lawyers engaged in claim drafting and the complexity of interpreting claims for combinations (e.g., of process steps, structural elements, or ingredients) as a result of its inclusion in the law is even now only gradually becoming apparent.

The genesis of §112, 6 is best understood in the context of a principle of American patent law enunciated by the Supreme Court in O’Reilly v. Morse, 56 U.S. (15 How.) 62, 112, 113 (1853) which condemns broad functional language in patent claims as an effort to preclude further research and development within the scope of the function addressed, at least for the life of the patent containing such a claim. The principle is still valid today in some contexts, including that of an invention claimed in terms of a single means plus its function. The principle was applied by the Supreme Court in Halliburton Oil Well Cementing Co. v. Walker, 329 U.S. 1 (1946), to invalidate claims to an improved oil well drilling apparatus wherein the improveMent lay in several functionally defined "means". The Court acknowledged that if the patentee had claimed the physical structure of these means rather than their functional characteRistics, the claims would have been valid.

A large segment of the practitioners of patent law objected vigorously to the Halliburton decision and sought a way to cure the precise problem the Court had explicated. The result was §112, 6. This provision does not overrule the principle on which the Halliburton decision rests, but does temper the application of the rule so as to allow claims for "combination" inventions to define one or more of the elements of the combination simply "as a means or step for performing a specified function" rather than in terms of "structure, material or acts". It carefully limits the coverage of the functional recitation in the claim to "the corresponding structure, material, or acts described in the specification" and their equivalents.

The "equivalents" referred to in §112, 6 are means or steps equivalent to the corresponding structure, materials or acts that the specification discloses and they must perform the identical function that the disclosed items perform. It is also crucial, in order to satisfy the Supreme Court’s concerns expressed in Halliburton, as well as in the decisions of the Court of Appeals for the Federal Circuit (e.g., Chiuminatta Concrete Concepts, Inc. v. Cardinal Industries, Inc., 145 F.3d 1303 (Fed. Cir. 1998); Al-Site Corp. v. VSI Int’l Inc., 50 USPQ2d 1161 (Fed. Cir. 1999)), that these equivalents, which fall within the literal scope of a §112, 6 type of claim, have been publicly known and available at the time the patent claim issued.

The examination of 35 U.S.C. §112, 6 claims by the U.S. Patent and Trademark Office ("PTO") and the interpretation of those claims in the courts have been attended by prolonged confusion. The source of the PTO’s confusion rested on its long-standing practice of giving each term of every patent application claim its broadest reasonable interpretation and fashioning rejections based on that interpretation. As the latest edition of the Manual of Patent Examining Procedure ("MPEP") §2181 acknowledges:

. . . past practice was to interpret a "means or step plus function" limitation by giving it the "broadest reasonable interpretation." Under the PTO’s long-standing practice this meant interpreting such a limitation as reading on a prior art means or step which performed the function specified in the claim without regard for whether the prior art means or step was equivalent to the corresponding structure, material or acts described in the specification.

The examination and rejection of §112, 6 type claims in this manner remained PTO practice until about five years ago -- and undoubtedly caused many patent applicants and their attorneys to reword claims of this type by substituting structure, materials or acts described in the specification for functional description, rather than going through a lengthy appeal process. The Federal Circuit’s decision in In re Donaldson, 16 F.3d 1189 (Fed. Cir. 1994), directed the PTO to adopt a changed approach to the examination of §112, 6 claims. MPEP §2181 now explicitly requires examiners to view the individual elements of these claims "as limited to the corresponding structure, materials or acts described in the specification and equivalents thereof" during the examination process.

Confusion among patent applicants, patentees, competitors of patentees and patent attorneys about how to draft a claim to bring it within §112, 6 and how to interpret such a claim, once issued, remains at a high level even now. In part, this may be attributed to the desire of many for a simple formula that can be availed of virtually automatically, both in drafting and understanding claims.

Unfortunately, as the relevant decisions of the Federal Circuit show, these §112, 6 claims cannot be forced within a formula; they are as different from one another as the inventions they seek to cover. Fortunately, the Federal Circuit is engaged in making an earnest effort, through its decisions, to establish useful guidelines that should be availed of in drafting and interpreting these claims.

It is especially fortuitous that this effort, already well under way, coincides with the onslaught of software patenting that has occurred within the last year in the United States. The §112, 6 type of claim lends itself especially serendipitously to the articulation of software inventions, most of which involve a combination of steps and are often difficult to cover in other claim formats. (So stating is not in any way intended to deprecate the attractiveness of the §112, 6 claim form for covering improved apparatus and machinery inventions, multi-step processes of every nature and even some compositions of matter.)

Preliminarily, it is critical to recognize that all of the general principles and canons of claim interpretation (and claim writing as well) that have been established over many years must be applied to §112, 6 claims. Their interpretation is a question of law for the court, under Markman v. Westview Instruments, 52 F.3d 967 (Fed. Cir. 1995) (en banc); aff’d, 517 U.S. 370 (1996), and it requires the interpreter to gain a thorough understanding of the patent specification, the other claims in the patent, the prosecution history and the prior art, as well as any extrinsic evidence that may be needed.

Apart from these and other general considerations, however, it is important to be aware of what distinguishes the §112, 6 claim from other types of claims and how small changes in claim language can either call this provision into play or exclude its consideration altogether.

First of all, while the presence of "means" or "step" in a claim does invoke "a presumption that the . . . term [is used] advisedly to invoke the statutory mandates for means-plus-function clauses", (York Products, Inc. v. Central Tractor Farm and Family Ctr., 99 F.3d 1568, 1574 (Fed. Cir. 1996)), these words are not formulaic. As said in Cole v. Kimberly-Clark Corp., 41 USPQ2d 1001, 1006 (Fed. Cir. 1996) "[t]he converse is also true; merely because an element [of a patent claim] does not include the word ‘means’ does not automatically prevent that element from being construed as a means-plus-function element" [citing Raytheon v. Roper Corp., 220 USPQ 592, 597 (Fed. Cir. 1983) where functional language preceded by "so that" was deemed equivalent to "means for" language].

Furthermore, the inclusion of "means for" or "step for" in a claim does not always invoke §112, 6 despite the presumption set forth above. For example, in Rodime PLC v. Seagate Technology, Inc., 50 USPQ2d 1429 (1999), a claim that recited "positioning means" plus its function and also included a recitation of some seven specific components of this "means" was held to be outside §112, 6. As the court put it, "a detailed recitation of structure for performing the . . . function takes this claim element out of the scope of §112, 6" (50 USPQ2d at 1435).

In Unidynamics Corp. v. Automatic Products Intnat’l Ltd., 48 USPQ2d 1099 (Fed. Cir. 1998), by contrast, the claim term "spring means tending to keep the door closed" was deemed to be within §112, 6 even though the word "spring" is a structural term. The court noted that ". . . spring is the only recitation of structure with the remainder pertaining solely to the function of the means limitation" (48 USPQ2d at 1105). In Unidynamics, the court also cautioned that the specification (or at least the prosecution history) must link every claim term recited in means-plus-function language to the specific disclosed structure that performs that particular function, saying

Structure disclosed in the specification . . . is only "corresponding structure" to the claimed means under §112, 6, if the structure is clearly linked by the specification or the prosecution history to the function recited in the claim. (Id.)

Rodime, supra, 50 USPQ2d at 1434, emphasizes that reciting a "means" (or "step") element in a claim without reciting a specific function for that element removes the claim from the ambit of §112, 6.

In Seal-Flex v. Athletic Track and Court Construction, 50 USPQ2d 1225, 1232-1235 (Fed. Cir. 1999), which invoked a process claim, Judge Rader wrote a separate concurring opinion in which he meticulously explained the correlation of means-plus-function claims to step-plus-function claims, the latter having received less detailed consideration to date by the Court than the former. (His fellow judges on the same panel, while acknowledging that his "analysis may be correct" stood aside because "some of . . . [it] breaks new ground" and involves "issues that have never been briefed" (50 USPQ2d at 1236)). Because the Rader analysis is clear, logical and fully in step with the Court’s earlier holdings regarding means-plus-function claims, there is very little likelihood that any practitioner who pays it heed and follows its advice will make any serious error.

Judge Rader notes, in particular,

[t]he difficulty of distinguishing acts from functions in step-plus-function claim elements . . . places a significant burden on the claim drafter to choose language with a definite and clear meaning. To invoke a presumption of §112, 6 application, a claim drafter must use language that expressly signals the recitation of a function as distinguished from an act.

As used in §112, 6, "step" is the generic term for "acts" in the same sense that "means" is the generic term for "structure" and "material." . . . The word "step," however, may introduce either an act or a function depending on context within the claim. Therefore, use of the word "step," by itself, does not invoke a presumption that §112, 6 applies. For example, method claim elements may begin with the phrase "steps of" without invoking application of §112, 6. . . .

Unlike "of," the preposition "for" colloquially signals the recitation of a function. Accordingly, the phrase "step for" generally introduces functional claim language falling under §112, 6.

The step-plus-function claim format will necessarily be heavily invoked as more and more patent applications covering software processes are filed and increasing numbers of patents covering such processes are issued.

In this context, it is particularly noteworthy that in Serrano v. Telular Corp., 42 USPQ2d 1538 (Fed. Cir. 1997), the Court construed a claim to a hardware "system" for interfacing a telephone device with a cellular radio transceiver, one element of which was a "determination means . . . for automatically determining the last digit" dialed from the telephone. Declining to limit this "means" to the circuitry disclosed as "preferred", the court held as follows:

[T]he specification clearly evidences that the invention is not limited to use of discrete logic circuitry and may alternatively be implemented using a microprocessor operating under software control . . . . Accordingly, we construe the "determination means" limitation to mean the function of determining when the last digit or number is dialed and to permit structure that includes digit analysis or use of a time-out feature, being implemented in discrete logic or with a microprocessor operating under software control, and equivalents of such structures. (42 USPQ2d at 1542)

To sum up, patent applications that are to include §112, 6 claims, require special care in the drafting of the specification and the claims. In particular, it is critical to provide a link between each means-plus-function or step-plus-function element recited in a claim and the corresponding "means" or "step" of the specification. In addition, whenever possible, it will be useful in the event of later litigation, to identify in the specification some examples of equivalent structure(s), material(s), or act(s) to each such "means" or "step".

Interpreting issued patent claims that contain "means" or "step" language requires careful attention to the principles and caveats discussed above, in addition to those that must be invoked in analyzing patent claims that do not include such terminology.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.