concurring.
I agree that the district court’s grant of JNOV to defendants must be affirmed, and I join in Judge Rich’s opinion. I enter this concurrence only to emphasize that our ground of decision is required implicitly by Graver Tank and Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 70 S.Ct. 854, 94 L.Ed. 1097, 85 USPQ 828 (1950) and explicitly by Lear Siegler, Inc. v. Sealy Mattress Co., 873 F.2d 1422, 10 USPQ2d 1767 (Fed.Cir.1989). For me what is fatal in this record is the failure of Mr. Malta to separate and explicate his comparative analysis *1329of “way” from his comparison of “function” and “result,” and to substantiate it. All three requirements of Graver Tank were discussed together, with only two fleeting, conclusory and inferential references to way. Consequently, there was insubstantial evidence of infringement under the doctrine of equivalents as to way, and therefore the verdict of infringement under the doctrine cannot be sustained.
I. THE LAW
In Lear Siegler, 873 F.2d at 1425-26, 10 USPQ2d at 1770, this court clarified a specific requirement that must be met before the question of infringement under the doctrine of equivalents may be submitted to the trier of fact for decision. To survive a motion for a directed verdict or a JNOV, a patentee must present “substantial evidence” comparing the claimed and accused inventions to one another as to each of the three aspects of equivalency set forth in Graver Tank, 339 U.S. at 608, 70 S.Ct. at 856, 85 USPQ at 330 — “function,” “way,” and “result.” Lear Siegler, 873 F.2d at 1425-26, 10 USPQ2d at 1770. In Lear Sie-gler, we said
[t]he party asserting infringement must present “evidence and argument concerning the doctrine and each of its elements.” ... While we do not doubt the ability of a jury to decide the factual issue of equivalence, to enable the jury to use its ability, Nestier requires that the three Graver Tank elements must be presented in the form of particularized testimony and linking argument.
873 F.2d at 1425-26, 10 USPQ2d at 1770 (citing Nestier Corp. v. Menasha Corp.-Lewisystems Div., 739 F.2d 1576, 1579, 222 USPQ 747, 749 (Fed.Cir.1984) (5-judge panel), cert. denied, 470 U.S. 1053, 105 S.Ct. 1756, 84 L.Ed.2d 819 (1985) (emphasis in original)). Thus, under Nestier Corp. and Lear Siegler, substantial evidence of comparison as to function, way, and result is required as part of the patentee’s prima facie case of infringement under the doctrine. Therefore, if the comparison evidence is not substantial, the issue may not be submitted to the jury. Or, if the trial court erred and the jury was allowed to decide the issue and returned a verdict for patentee, JNOV must be granted.
We have also held that the comparison as to each Graver Tank element must be made “explicitly” and “separately.” Lear Siegler, 873 F.2d at 1425-26, 10 USPQ2d at 1770. Consequently, a jury verdict of infringement under the doctrine can only survive a motion for JNOV if substantial evidence was presented that explicitly and separately compares the function/way/result of the accused device with the function/way/result of the claimed invention to show that they are substantially the same. That was not done here as to way.
Compliance with Lear Siegler is a question of law, which we review de novo. On a motion for directed verdict or JNOV, the trial judge must decide such an issue of law by assessing whether evidence of comparison that is substantial, separate and explicit was introduced by the patentee as to each aspect of infringement by equivalents. See Senmed Inc. v. Richard-Allan Medical Indus., 888 F.2d 815, 818, 12 USPQ2d 1508, 1511 (Fed.Cir.1989).
II. THE LAW APPLIED TO THIS CASE
The trial judge conducted such an assessment here. In reviewing this legal issue de novo, we decide he was correct in concluding the evidence was not substantial.
As the dissent details, in the instant case extensive evidence was presented about how the striking surfaces of the accused bell work. The jury was not separately and explicitly told, however, that drilling slots behind striking surfaces on a clapper made of the same plastic material is an equivalent “way” compared to attaching striking buttons made from different materials. To be sure, the jury was told and shown that the “function” and “result” of their clappers striking the bells were the same, and indeed these two aspects of equivalency are all but uncontested. And, while explaining the similarity of function and result, Mr. Malta may have briefly implied that the way was also essentially the same, the jury certainly was not told *1330how and why that was so. In other words, plaintiffs separate and explicit comparison evidence was sufficient to establish only two of the three Graver Tank requirements. The testimony as to “way” was not substantial. Nor was it separate and explicit. Rather, it was brief, intermingled, inferential and conclusory. Because Lear Siegler clearly requires separate, explicit and substantial comparison evidence as to all three requirements, the case should not have been submitted to the jury, and thus the jury verdict cannot stand.
III. THE DISSENT
The dissent suggests that the majority has added “a new requirement of proof of equivalency: proof of not only the three Graver Tank ‘prongs’ of ‘function, way, and result’, but also a fourth prong of ‘why’.” Such a characterization of the majority’s holding is inaccurate. Because often substantial proof of equivalence of “way” can be made only by an explanation of “how and why,” the apparently separate requirement of proof of “why” is actually only an elaboration on the requirement of equivalence as to “way.”
To my mind, it is clearly no answer to point, as does the dissent, to the great quantity of evidence on the general operation of each of the two bells at issue in this case, i.e., the commercial embodiment of the claimed bell and the accused bell. No amount of purely descriptive evidence about either can suffice, absent separate, explicit and substantial comparison evidence that the clapper “striking surfaces” work in the same “way” as the “buttons.”
That the instructions did not contain erroneous statements of law, were reasonably comprehensive, and went unchallenged is immaterial. Defendants did move for a directed verdict, both at the end of plaintiffs’ case and again at the close of all the evidence. The stated ground was insufficiency of the evidence on infringement. No reason has been advanced why they should also be required to make the vain gesture of objecting to a facially proper charge of infringement by equivalents. In any event, Fed.R.Civ.P. 50(b) explicitly states that whenever a motion for directed verdict is denied, “the court is deemed to have submitted the action to the jury subject to a later determination of the legal questions raised by the motion.” As was noted earlier, compliance with Lear Siegler is a legal question.
Moreover, Lear Siegler is based on the very premise that sufficiency of instructions cannot cure an insufficiency of proof as to the three Graver Tank requirements. The reason we do not allow curing by instructions is that even with perfect jury instructions, determining infringement by equivalents would still be guesswork for a jury unless it is given separate, explicit and substantial evidence of comparison as to each requirement of Graver Tank. After all, such comparisons are what infringement by equivalents is all about. As the district court noted, the danger that Lear Siegler, building directly on Nestier Corp., is designed to prevent is that of the doctrine of equivalents becoming “a result oriented catch-all.” Malta v. Schulmerich Carillons, Inc., 13 USPQ2d 1900, 1903 (E.D.Pa.1989).
The simplicity of the bells, so emphasized by the dissent, is not relevant either. In Lear Siegler, the devices at issue — mattress springs — were equally simple and in no manner implicated complex technology. However, the rule of Lear Siegler is a prophylactic rule of general applicability. As such, it must cover the whole range of infringement cases, many of which do indeed involve complex technology. I would agree, though, that the more complex the technology, the greater the need for the rule. But that is not to say there can be any case where this rule does not apply. In requiring sufficient evidence on each aspect of equivalence, Lear Siegler merely makes explicit what Graver Tank implied.
Nor is it relevant that, as the dissent notes, slots in the clapper material were well known in the prior art, for the obviousness of the “way” cannot explicate for judge or jury that it is equivalent, i.e., substantially the same, much less how and why. That clapper surfaces with slots were known as an alternative to buttons *1331of differing materials does not necessarily make them an equivalent. In fact, obviousness is simply non-probative of the three-part test of equivalence.
Contrary to the dissent, the rule of Lear Siegler does not implicate the jury’s prerogatives, under the Constitution, the case law, the Federal Rules of Civil Procedure, or otherwise. It simply addresses whether the evidence is sufficient to permit submission of the issue to the jury at all. It is thus a rule that restricts judges, not jurors.
The dissent also suggests that Schulme-rich’s failure to request jury instructions on the rule of Lear Siegler means Schulme-rich waived the protections of the rule. As a rule that restricts judges and not jurors, its purpose is to establish when the issue of infringement by equivalents may be given to the jury. It is thus not subject to waiver because of suggested jury instructions, or the lack thereof.
Finally, contrary to the suggestion of the dissent, in my view there is not a genuine issue of retroactive application of new law. While Judge Rich’s opinion relies primarily on statements in Nestier Corp., decided before the trial of this case, as first setting forth the requirement restated in Lear Sie-gler, decided after this trial, to overcome the dissent’s argument on retroactivity, there is a simpler answer. I submit that requiring separate, explicit and substantial comparison evidence of each of the three Graver Tank aspects of equivalency has been the law at least since 1950 when Graver Tank itself was decided. If Lear Siegler added gloss thereto, it was on peripheral points not dispositive here, such as the requirement of “testimony” (as opposed to other forms of evidence) and “linking argument” (which, being only attorney assertions, is of course not evidence at all).
IV. CONCLUSION
Generally speaking, both the purpose and effect of the rule of Lear Siegler are to minimize the risk that a jury will find infringement under the doctrine of equivalents merely .because one or two of the three Graver Tank requirements is met, ignoring the other(s) or blindly assuming the other(s) must be met, too. Thus, Lear Siegler requires that before a case may be submitted to a jury, a patentee’s proof must include substantial evidence of separate and explicit comparison of the claimed and accused devices as to each of the three Graver Tank requirements. A case based solely on descriptive evidence, no matter how extensive, may not go to the jury. Nor may a case lacking separate, explicit and substantial evidence on each of the Graver Tank requirements of equivalence.
Here, no separate and explicit comparison evidence at all was presented as to whether, how and why the clapper surfaces of the same plastic material with slots drilled behind them operated in the same “way” as the striking buttons made of materials of different hardness. Instead, brief, inferential and conclusory references to way were buried in answers dealing primarily with function and result. That is not substantial evidence and the jury certainly would not appreciate it as evidence of way. Thus, an error of law occurred in submitting the case to the jury.
I join Judge Rich’s opinion affirming the district court’s judgment of no infringement despite the verdict. I set forth these concurring views in order to clarify Lear Siegler.