DAWN EQUIPMENT CO. v. KENTUCKY FARMS INC

PLAGER, Circuit Judge.

In this patent infringement case, the jury determined that the accused device, although not literally infringing, infringed under the doctrine of equivalents. The trial judge gave judgement accordingly, and denied defendant's motion for judgement as a matter of law ("JMOL"). Because on these facts no reasonable jury could have found infringement, we reverse the denial of defendant's motion for JMOL and order judgment for the defendant.

Plaintiff Dawn Equipment Company ("Dawn Equipment") sued defendant Kentucky Farms Incorporated ("Kentucky Farms") for infringement of U.S. Patent No. 5,129,282 ("'282 patent"), entitled "Mechanism for Selectively Repositioning a Farm Implement." Shortly before holding a jury trial, the trial judge held a Markman hearing to construe the only asserted patent claim. The trial judge instructed the jury on his claim construction and thereafter submitted the issues of literal infringement and infringement under the doctrine of equivalents to the jury. The issues were submitted by way of two special interrogatories that asked the jury to answer with a simple yes or no whether there was literal infringement and whether there was infringement under the doctrine of equivalents. The jury returned its verdict, answering "no" to literal infringement and "yes" to infringement under the doctrine of equivalents. Kentucky Farms filed a motion for JMOL on the doctrine of equivalents infringement verdict. The trial judge denied the motion, and this appeal followed.

The '282 patent discloses a device for adjusting the height of a farm implement such as a row cleaning device. A row cleaning device, which frequently consists of a pair of wheels having sharp teeth, is often attached to a planter to clear residue from the planter's path. In pointing out problems in the prior art, the '282 patent describes prior art "multi-hole pinned height adjustment" mechanisms. '282 patent, col. 1, l. 55, to col. 2, l. 29. The patent explains that raising or lowering such prior art mechanisms can be very time-consuming, tedious, and repetitive. Adjusting the height of such mechanisms requires the operator to manually elevate and shift the farm implement to align holes and insert pins. The patent also explains that the loose pins used in the prior art mechanisms are easily lost. Moreover, when adjusting the height of such a prior art mechanism, the operator is required to place himself beneath the farm implement, which increases the risk of accidents and injuries.

The '282 patent explains that these problems are avoided by using an improved mechanism, illustrated in Figures 1 and 2 of the patent, reproduced below.

PLAGER, Circuit Judge, additional views.

I write additionally because I find the law in this area confused and confusing. The limitations in the claim at issue are drawn in means-plus-function form pursuant to 35 U.S.C. § 112, ¶ 6 (1994). Section 112, paragraph 6 provides that such limitations "may be expressed as a means . . . for performing a specified function without the recital of structure, material, or acts in support thereof . . . ." When so expressed, "such claim [limitations] shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof." 35 U.S.C. § 112, ¶ 6 (emphasis added).

It is established law that, when an accused product satisfies such claim limitations by way of structure equivalent to that described in the specification (and otherwise satisfies the requirements for infringement), the infringement is deemed literal infringement. See, e.g., P.M. Palumbo v. Don-Joy Co., 762 F.2d 969, 975 n. 4, 226 USPQ 5, 8 n. 4 (Fed. Cir. 1985) (noting that use of an "equivalent" under § 112, ¶ 6 leads to literal infringement rather than infringement under the doctrine of equivalents). Thus, with regard to claim limitations drawn pursuant to § 112, ¶ 6, the notion of literal infringement, as distinct from infringement under the doctrine of equivalents, includes equivalents.

What place then is there for the doctrine of equivalents with regard to such claim limitations? Opinions of this court have attempted to draw a distinction between what is meant by an equivalent under § 112, ¶ 6, and what is meant by an equivalent under the doctrine of equivalents. The implicit assumption is that, as a matter of law, a patentee with a § 112, ¶ 6 claim has a choice of alleging infringement under either or both, and the trier of fact is free to find that the accused product does not infringe under the one kind of equivalent, but does under the other.

One problem with this approach is that it assumes that there are clearly defined operational differences between these two notions of equivalents, and that triers of fact (usually, whether judge or jury, persons unfamiliar in the first instance with the technology at issue, much less the legal conceptualizations) can readily differentiate between them. Two cases from this court in recent years have spoken to the distinctions between the two types of equivalents, and have attempted to draw out the character of these differences: Valmont Industries., Inc. v. Reinke Manufacturing Co., 983 F.2d 1039, 1041-44, 25 USPQ2d 1451, 1453-55 (Fed. Cir. 1993); and Alpex Computer Corp. v. Nintendo Co., 102 F.3d 1214, 1222, 40 USPQ2d 1667, 1673-74 (Fed. Cir. 1996), cert. denied, 117 S.Ct. 2480 (1997).

The cases cast the differences in terms of separate origins and purposes, and that the different equivalents have different "application." Valmont, 983 F.2d at 1043-44, 25 USPQ2d at 1454; Alpex, 102 F.3d at 1222, 40 USPQ2d at 1673. On the other hand, they are in agreement that the term "equivalent" in both statute and doctrine, to employ the phrase used in Valmont, "invokes the familiar concept of an insubstantial change which adds nothing of significance." Valmont, 983 F.2d at 1043, 25 USPQ2d at 1455; see also Alpex, 102 F.3d at 1222, 40 USPQ2d at 1673-74. This suggests at the least that the tests for equivalence under the statute and the doctrine are quite similar, if not the same.

The Valmont and Alpex courts attempt to distinguish the tests on several grounds. The Alpex court opines that under the statute the accused product is compared to the structure disclosed in the specification corresponding to the means-plus-function claim limitation, whereas under the doctrine the accused product is compared to the claim limitation. Alpex, 102 F.3d at 1222, 40 USPQ2d at 1673-74. The Valmont court went further and opined that a statutory equivalent under § 112, ¶ 6 "does not involve the equitable tripartite test of the doctrine of equivalents," i.e., the so-called function-way-result test. Valmont, 983 F.2d at 1043, 25 USPQ2d at 1455. This was thought to follow from the fact that "the sole question" under § 112, ¶ 6 involves comparison of the structure in the accused product to the structure in the specification. Id.

However, these perceived distinctions appear to be either nonexistent or without significance, or are at least beyond what we can reasonably expect the triers of fact to sensibly discern. With regard to the distinction set forth in Alpex, the comparison, for purposes of the doctrine of equivalents, of an accused product to a claim limitation drafted pursuant to § 112, ¶ 6 necessarily involves a comparison to the corresponding structure described in the specification. This is because § 112, ¶ 6 mandates that such limitations are to be construed to cover the described corresponding structures (and their equivalents). Indeed, if the comparison under the doctrine is merely to the language in the claim, the comparison cannot be meaningfully made because, by definition, the § 112, ¶ 6 claim limitation recites no structure, material or acts.

Considered another way, without reference to the corresponding structures described in the specification, any and all structures which perform the specified function would satisfy the claim limitation under the doctrine. That is clearly not the law of this court. For example, in Valmont, in applying the function-way-result test for purposes of the doctrine of equivalents, the court determined that there was not infringement, under the doctrine, of a claim drafted pursuant to § 112, ¶ 6 because the accused device was very different from that described in the patent. Valmont, 983 F.2d at 1044, 25 USPQ2d at 1456. Thus, whether considering infringement under § 112, ¶ 6 or the doctrine of equivalents, a comparison must be made to the described structure corresponding to the § 112, ¶ 6 claim limitation.

With regard to the suggestion in Valmont that the function-way-result test is not applicable to determining equivalence under § 112, ¶ 6, it is not readily apparent why use of the "way" and "result" parts of the tripartite test, to the extent that test is useful at all, would not also be helpful in the § 112, ¶ 6 context. (With regard to the "function" part of the test, the statute already carries with it a requirement that the specified function be the same.) Indeed, in a case decided prior to Valmont, this court opined that the same tripartite test does apply to determining equivalence under the statute:

Whether the issue is equivalency of a means that is described in the specification to perform a function in a "means" clause of a combination claim (i.e., literal infringement), or equivalency to the claimed invention as a whole (i.e., infringement by the doctrine of equivalents), the test is the same three-part test of history: does the asserted equivalent perform substantially the same function in substantially the same way to accomplish substantially the same result. (In the case of "means" clauses, of course, the function is that stated in the claim.)

Texas Instruments, Inc. v. United States Int'l Trade Comm'n, 805 F.2d 1558, 1571, 231 USPQ 833, 841 (Fed. Cir. 1986). Furthermore, given the statements in Valmont and Alpex that under both statute and doctrine the issue is insubstantial changes and, given this court's more-recent statement that the question of insubstantial differences under the doctrine may be satisfied by way of the tripartite test, see Hilton Davis Chem. Co. v. Warner-Jenkinson Co., 62 F.3d 1512, 1517-18, 35 USPQ2d 1641, 1645 (Fed. Cir. 1995) (in banc), rev'd on other grounds, 117 S.Ct. 1040, 41 USPQ2d 1865 (1997), it is difficult to understand why the tripartite test would not also be available to resolve the question of insubstantial changes under the statute.

There are no doubt other application details under the statute and doctrine that have developed in the case law over the years. One could attempt to distinguish the tests for equivalence based on such details. However, such an analysis begs the ultimate questions: What if any difference is there between the scope of protection provided? Can triers of fact sensibly discern any such difference? Given the substantial risk of confusion, should there be two notions of equivalents?

To date, the descriptions offered of the differences between equivalents under the statute and under the doctrine, though they may accurately capture the two ways in which the notion of equivalents has developed and is thought to function, provide little of real guidance to a trier of fact called upon to distinguish the scope of one kind of equivalent from the other. More to the point, the existence of two "different" notions of equivalents cannot help but add a further source of confusion, especially when submitted to a jury for decision based on the kinds of explanatory material available in the cases.

In the case before us, the jury was charged to answer whether the claim at issue was literally infringed. The jury's response was "No." Because the claim consisted solely of means-plus-function limitations, literal infringement required a finding that the accused device performed the specified functions recited in the means-plus-function limitations with structure the same as or equivalent to the corresponding structure described in the specification. See, e.g., Valmont, 983 F.2d at 1042, 25 USPQ2d at 1454 (setting forth the test for literal satisfaction of a means-plus-function limitation). There appears to be no genuine issue with regard to the specified functions; the accused device appears to perform the functions recited in the means-plus-function claim limitations (and I assume such to be the case). Thus, as a matter of statutory construction and controlling precedent, the jury verdict on literal infringement means that, in the jury's view, the accused device had neither the corresponding structure described in the specification nor equivalents thereof.

But the jury was further charged to answer whether the claim at issue was infringed under the doctrine of equivalents. To this question the jury answered "Yes." What could that mean? The jury, by its vote on literal infringement, had already ruled out infringement based on the corresponding structure, and, as a matter of established law, it had also ruled out infringement based on equivalent structure, because that also would have been properly classified as "literal" infringement.

Given that, a finding of infringement under the doctrine of equivalents could only mean that there is something perceivably different between an equivalent under the doctrine and the equivalent, or lack thereof, under the statutory test. What this could possibly be escapes me. Beyond that, is it possible that the jury thought there was something called an equivalent of an equivalent, and that is what the jury found to exist?

These are not simply matters of semantics. They go to the very act of deliberative decision making, decision making based on a meaningful rule of law. However many variations there are in the words we use to describe the criteria by which to determine when something in fact is the "equivalent" of something else, see, e.g., Hilton Davis, 62 F.3d at 1517-18, 35 USPQ2d at 1645 (defining equivalence as "insubstantial differences" and mentioning that that test may be satisfied where the function, way and result are substantially the same), the basic notion of equivalence does not vary. An equivalent is something that is "equal in force or amount," "like in signification or import," "synonymous," etc. Webster's Third New International Dictionary 769 (1986). If B is not the equivalent of A, using one understanding of equivalent, can it be said that B is the equivalent of A, using a second undefined or similarly understood meaning of equivalent? Worse yet, can it be said that B is the equivalent of the (unknown) equivalent of A? Stating a rule of law to permit that manner of thinking is simply an invitation to confused thinking. It certainly invites results that defy understanding.

Our cases seem to assume, without examining the question beyond that discussed above, that these two different kinds of equivalents exist, and that they are available to a trier of fact when dealing with infringement of a claim drafted pursuant to § 112, ¶ 6. See, e.g., Alpex Computer Corp. v. Nintendo Co., 102 F.3d 1214, 40 USPQ2d 1667 (Fed. Cir. 1996) (in reviewing a jury verdict of infringement, analyzing whether a means-plus-function limitation was satisfied literally or under the doctrine of equivalents), cert. denied, 117 S.Ct. 2480 (1997); Valmont Indus., Inc. v. Reinke Mfg. Co., 983 F.2d 1039, 25 USPQ2d 1451 (Fed. Cir. 1993) (same); Sofamor Danek Group, Inc. v. DePuy-Motech, Inc., 74 F.3d 1216, 37 USPQ2d 1529 (Fed. Cir. 1996) (in reviewing a denial of a motion for preliminary injunction, analyzing likelihood of success of establishing that a means-plus-function limitation was met literally or under the doctrine of equivalents); D.M.I., Inc. v. Deere Co., 755 F.2d 1570, 225 USPQ 236 (Fed. Cir. 1985) (reversing summary judgement of noninfringement upon finding genuine issues of fact existed as to whether a means-plus-function limitation was met literally or under the doctrine of equivalents). In the case before us, neither party seemed to find the idea of two different notions of equivalents problematical before or during trial, although on appeal Kentucky Farms argues that the jury's verdicts on literal infringement and infringement under the doctrine of equivalents are inconsistent.

Though the question of two kinds of equivalents has never been addressed head-on by this court, commentators have addressed it, and found this court's practice anomalous. See Laurence H. Pretty Janene Bassett, Reconciling Section 112, Paragraph 6 with the Doctrine of Equivalents in the Wake of Warner-Jenkinson Co. v. Hilton Davis Chemical, 489 PLI/Pat 359, 378, 391-92 (1997) (concluding that the equivalence analyses under § 112, ¶ 6 and the doctrine of equivalents are virtually the same and therefore proposing the adoption of a single equivalence analysis for means-plus-function limitations); Mark D. Janis, Unmasking Structural Equivalency: The Intersection of § 112, ¶ 6 Equivalents and the Doctrine of Equivalents, 4 Alb. L. J. Sci. Tech. 205, 227 (1994) (concluding that § 112, ¶ 6 and the doctrine of equivalents share the same concept of equivalence and therefore recommending that the same test of equivalence be used for both).

It should be remembered that § 112, ¶ 6 was a legislative solution to a problem in claiming — broadly stated claims using means-plus-function language were too vague to be judicially enforced. See Valmont, 983 F.2d at 1042, 25 USPQ2d at 1453-54 (noting that § 112, ¶ 6 was enacted in response to the Supreme Court prohibiting certain use of means-plus-function language in Halliburton Oil Well Cementing Co. v. Walker, 329 U.S. 1 (1946)). The purpose of § 112, ¶ 6 was to provide clear parameters within which means-plus-function claims could be drawn and sensibly construed. Speaking in terms of dual and competing notions of equivalents seems to me to be wholly inconsistent with that legislative purpose. Furthermore, the doctrine of equivalents is a judge-made solution to a concern about overly-literal infringers. Congress having expressly provided against an overly-literal reading of § 112, ¶ 6 claims by allowing for equivalents, there would seem to be no justification for intrusion by the courts to duplicate or differ from the legislative solution.

In that light, and consistent with that purpose, I believe that the practice of claiming under § 112, ¶ 6 would be much improved if we adhered to the proposition that the "equivalents" of "structure, material, or acts described in the specification" are those found to be within the scope of that term as it is used in § 112, ¶ 6, and not elsewhere. Accordingly, the separate judicially-created doctrine of equivalents would have no application to those aspects of limitations drawn in means-plus-function form. This result is fully consistent with the legislative purpose of § 112, ¶ 6 and with its plain language which expressly provides for equivalents with regard to those parts of a means-plus-function claim for which Congress chose to permit equivalents.

In the case before us, whether one views the jury's verdict as finding equivalents solely under the statutory grant or under the judicially-defined doctrine of equivalents, no reasonable jury could have found that the accused device was equivalent. Whether the error would have been avoided had the jury been limited solely to determining literal infringement (including of course one level of "equivalents"), is unknown, and for this case at least, irrelevant. I do believe, however, that limiting a jury (as well as ourselves) to one notion of equivalents at a time can only help.

NEWMAN, Circuit Judge, additional views.

I write separately to respond to the "additional views" filed by Judge Plager. With all respect to my thoughtful colleague, his proposal that established law should be changed, even were such change available to the judges of this court, simply moves the Federal Circuit farther from the principles of stare decisis. This already difficult area of law will not benefit from added uncertainty.

The distinction between the doctrine of equivalents and section 112 equivalents, if confusing to jurors, has long been understood by practitioners of patent law. These different rules serve different purposes. Other than further to restrict the doctrine of equivalents, I know of no policy reason for eliminating access to the doctrine of equivalents with respect to the claimed function when claims are written in "means-plus-function" form. The style of claims is not the sine qua non of the patent right, and the equitable purposes of the doctrine of equivalents do not rise and fall with whether the patentee used the claim form authorized in section 112 paragraph 6.

Precedent has often explained and implemented the distinct purposes of these two practices. E.g., Pennwalt Corp. v. Durand-Wayland, Inc., 833 F.2d 931, 934, 4 USPQ2d 1737, 1739 (Fed. Cir. 1987) (en banc) ("Section 112, paragraph 6, plays no role in determining whether an equivalent function is performed by the accused device under the doctrine of equivalents."); Alpex Computer Corp. v. Nintendo Co., 102 F.3d 1214, 1222, 40 USPQ2d 1667, 1673 (Fed. Cir. 1996) ("While equivalency under the doctrine of equivalents and equivalency under § 112, ¶ 6, both relate to insubstantial changes, each has a separate origin, purpose and application."); Valmont Industries Inc. v. Reinke Manufacturing Co., 983 F.2d 1039, 1043, 25 USPQ2d 1451, 1454 (Fed. Cir. 1993) ("The doctrine of equivalents has a different purpose and application than section 112.") Although laypersons may have trouble understanding this distinction, that can be said of many areas of law. Indeed, the jury problem that Judge Plager identifies in this case could have been easily avoided by presenting more explicit special verdicts.

The proposed elimination of recourse to the doctrine of equivalents for claim elements described in means-plus-function form would markedly diminish the scope of the doctrine. This step has no support in precedent. Whether or not further restriction on the doctrine of equivalents will be warranted as, in the fullness of time, more is learned of its role in the larger system of national innovation policy, it is inappropriate for this court to undertake such a major step sua sponte. Judge Plager's suggestion that the law is wrong will send a sure signal to litigants, opening every district court to the argument. This can not add stability to patent law, or certainty to those seeking to conduct their business in reliance on law.

MICHEL, Circuit Judge, additional views.

I wonder if affording the patentee additional protection under the doctrine of equivalents conflicts with the very language and intent of 35 U.S.C. § 112(6) (1994), which covers only those "equivalents" disclosed in the specification.

As the Supreme Court reemphasized in Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 117 S.Ct. 1040, 1051 (1997), the notice function of patents is critical. Market participants as well as judges and jurors must be able to ascertain what subject matter is covered by the right to exclude. The notice function is especially important for the patentee's competitors, who need to shape their behavior by relying on the patent file. The need for clear notice is all the greater in the case of means-plus-function limitations because the claim language alone does not define the scope of protection.

As we have construed section 112(6), a patentee who claims an element of a mechanical device using means-plus-function language is entitled to protection of the corresponding structure(s) described in the specification and all "equivalent structures" (or, as some of our cases have termed them, "structural equivalents," see, e.g., Alpex Computer Corp. v. Nintendo Co., 102 F.3d 1214, 1221 (Fed. Cir. 1996); Ven-Tel, Inc., v. Hayes Microcomputer Prods., Inc., 984 F.2d 1527, 1543 (Fed. Cir. 1992)). Congress thus provided the patentee with two benefits from section 112(6): first, it need not claim structure but can simply rely on the written description and drawings to obtain protection for all of its disclosed structures; and second, it gets protection of all equivalents of whatever structures it has disclosed in its specification. Did Congress intend that the price for those benefits was foregoing coverage of even broader equivalents under the doctrine?

Is it contrary to section 112(6) to expand the protection for inventions claimed partly in means-plus-function format by also applying the doctrine of equivalents to limitations claimed in that format, when protection for some but not all equivalents has already been incorporated into the statute itself and when doing so further diminishes the notice function of the patent? Or, did Congress intend the courts to apply the doctrine of equivalents to the means-plus-function format just as we apply the doctrine to structural formats? Until we are required to review a case in which these issues actually have been litigated, we cannot answer the questions raised in the three additional views here.