The April 1995 en banc decision of the United States Court of Appeals for the Federal Circuit in Markman v. Westview Instruments, Inc. (52 F.3d 979; aff’d 116 S.Ct. 1381 (1996)) effected a much-needed sea change in the way in which U.S. patent infringement litigation had been conducted during the preceding 20-25 years, both by trial courts and at the appellate level. As the en banc decision explains, it restored the question of patent claim interpretation (or "construction" -- a synonym for interpretation, as the majority opinion holds) to that of a question of law to be decided by the Court, rather than a question of fact triable by a jury. The Supreme Court had actually laid down this principle almost 150 years earlier, when patent claim language was far simpler, less carefully drawn and therefore usually more ambiguous than is permitted under U.S. patent acts adopted from 1870 onward, in Hogg v. Emerson (47 U.S. (6 How.) 437, 484 (1848)) and had followed it thereafter. The en banc Federal Circuit itself, however, acknowledged in Markman that it went astray in McGill, Inc. v. John Zink Co. (736 F.2d 666 (Fed. Cir. 1984)), and continued to do so throughout a line of cases that culminated in Tol-O-Matic, Inc. v. Proma Produkt-Und-Mktg. Gesellschaft mbH (945 F.2d 666 (Fed. Cir. 1991)). In addition, one can find the same type of departure from the Hogg v. Emerson principle in cases decided prior to the 1982 commencement of the Federal Circuit, especially in the approximately ten years preceding it.
Basically, the en banc Federal Circuit majority recognized three fundamental reasons for assigning the task of claim interpretation to the court to be determined as a matter of law, to wit: that (1) it is a fundamental principle of American law that judges have the responsibility to construe written instruments, from which it follows that appellate review is also always de novo; (2) a patent is a fully integrated written instrument; and (3) it is necessary and fair that competitors of a patentee be able to make a reasonable assessment of the scope of its patent claims from the publicly available written record of their procurement.
Corollary to this basic decision, the en banc Federal Circuit majority recognized the patent claims, the patent’s written description of the invention and the prosecution history as the primary sources for ascertaining the true meaning of claim language. As a secondary source this group further recognized extrinsic evidence, consisting of expert and inventor testimony, dictionaries and learned treatises, all or any of which are sometimes necessary to explain scientific principles, the meaning of technical terms used in the patent and its prosecution history, and to educate the court in the technology so it can distinguish between what was known at the filing date of the patent and what was newly disclosed in the underlying application.
The abuse of both the law itself and the public interest (as typified by the competitors whose rights the en banc court acknowledged) that the en banc Markman decision corrected is illustrated by the actual facts of the Markman case. Specifically, Markman (an individual) had used his own oral testimony and that of his expert to induce a jury to construe "cash" or "dollars" as falling within the scope of the claim term "inventory" in the context of the dry cleaning business. The patent and its prosecution history, however, clearly suggested that "inventory" referred to articles consigned to a dry cleaner for cleaning and articles cleaned by that establishment, and neither mentioned nor implied that money played a part in the concept.
The temptation to reinterpret claim terms long after patent issuance to make those terms extend far beyond the scope of both the patent’s literal disclosure and what those of ordinary skill in the field of the invention would reasonably understand that disclosure to embrace, has often been inviting to patentees and the lawyers whom they consult in deciding whether to bring a suit for patent infringement. This has been particularly true when the product (or process) to be charged as an infringement is competing vigorously with the patentee’s product, but would fall outside the patentee’s patent claims in the absence of reinterpretation of one or more of the claim terms. Such efforts at nunc pro tunc revision of a patent were extremely successful with juries in the 20-25 years preceding the en banc Markman decision. Indeed, it is likely that the concern of at least some Federal Circuit judges about apparently revisionary patent claim interpretations that appeared in some pre-Markman jury case appeals (which were affirmed because substantial testimonial evidence supported the verdicts) played a role in motivating the Court’s acceptance of Markman for an en banc hearing, a relatively rare occurrence.
In this regard, it is also reasonable to infer that the Supreme Court decision in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993) and Markman spring from a common thread of dissatisfaction on the part of appellate judges with jurors’ all-too-frequent gullibility in the face of "junk science" and "canned testimony" given by "hired gun" experts -- i.e., persons who willingly testify to whatever the party paying their "expert" fees wants proved.
Markman, of course, demands more work from the trial judge in arriving at a legal conclusion than is normally needed from that same judge in many other situations where a jury is to find the facts based in whole or in part upon scientific, technical or other "expert" evidence, because of the threshold responsibility to read the patent and its file history with care that Markman imposes upon him or her. And Markman goes on to state that "Extrinsic evidence is to be used for the court’s understanding of the patent, not for the purpose of varying or contradicting the terms of the claims" -- whereas the problem when expert evidence is to be properly weighed by the jury in the course of fact-finding, under Daubert and its progeny, is what expert evidence is sufficiently reliable to be a competent source of facts for the jury to weigh.
The en banc Markman majority spoke of the trial judge’s "among other things, using certain extrinsic evidence the court finds helpful and rejecting other evidence as unhelpful" in the process of claim construction. To understand the words "helpful" and "unhelpful" in this context, examination of Daubert and its progeny -- especially Kumho Tire Co. Ltd. v. Carmichael (67 U.S.L.W. 4179 (1999)) -- provides some insight. In this line of cases, the Supreme Court assigned to the trial judge, whenever expert opinion evidence may be important to fact-finding, the role of acting as "gatekeeper" under Federal Evidence Rule 702. In other words, the trial judge -- the gatekeeper -- may admit into evidence and thus allow a jury to consider reliable opinion evidence but must screen from the jury’s purview, by denying its admission into evidence, unreliable expert opinion. In discharging this function, the Supreme Court in Daubert afforded to the trial judge a wide discretionary latitude to test expert opinion evidence by investigating certain specifically identified factors, including but not limited to, the issues of whether the underlying theory or technique has been (or can reliably be) tested, whether it is generally accepted in the relevant field, and whether there are standards that control its operation or use. In Kumho, the Court extended Daubert by encouraging each trial judge to go beyond the specifically delineated factors the latter sets out whenever he or she perceives a need for greater clarity, by investigating the issue of reliability in any way each might deem appropriate to ensuring that the jury is exposed only to reliable expert testimony. In patent claim construction, where the judge is to determine an issue of law, the task of separating "helpful" from "unhelpful" expert testimony or other extrinsic evidence appears to be a somewhat similar task, even though the issue is not one of evidentiary admissibility.
The setting in this post-Markman era for patent claim construction is most commonly that of a separate pretrial proceeding devoted to that endeavor, wherein the opposing parties -- patentee and accused infringer -- present their separate arguments on the intrinsic evidence and their extrinsic evidence relating to claim construction. Sometimes "expert" opinion or other "expert" evidence may be developed orally before the trial judge; at other times -- most often if the hearing has been precipitated by the filing of a summary judgment motion as to patent infringement or validity -- the extrinsic "expert" evidence is presented and challenged in affidavit form and its implications are discussed in dialog between the judge and the opposing lawyers. In either case, however, no jury is present and the judge has the ultimate duty -- if and when a jury is later convened for the purpose of hearing and deciding any disputed fact issues in the case -- to instruct that jury on the meaning of the patent claims in issue.
At the pretrial Markman hearing, the judge’s focal concern in addressing expert evidence is that of determining whether it is "helpful" (and hence cognizable under the Markman majority en banc decision) or "unhelpful" (and hence to be wholly discarded). Viewed from this perspective, it is self-evident that if expert evidence is to be "helpful" in patent claim construction, it must be at least reliable -- and that hence the Markman line of precedent is readily relatable to the concerns that inspired Daubert and its progeny.
A major criterion of reliability in the context of the Markman hearing -- and perhaps in most cases the only criterion -- is whether the expert testimony offered is fully consistent with the claim as written, the written description of the invention in the patent itself and the patentee’s relevant representations made in its file history. If there is no consistency of certain evidence with at least the claim and the written description, logic and law alike demand that this evidence be discarded as "unhelpful". Indeed, the specifics of the Markman case itself follow precisely this line of reasoning in that the Federal Circuit en banc majority, and the trial judge in overruling the jury verdict as a matter of law, both recognized the "expert" evidence was beamed at effecting a virtual rewriting of the patent specification to place cash or dollars on the same footing as articles of clothing before the claim term "inventory" could be construed.
The Federal Circuit, in some of its post-Markman opinions, has rightly cautioned that any extrinsic evidence that tends to contradict or vary either the claim language per se, or the parts of the patent specification that support the claim language and give it meaning, is disentitled to consideration during the claim construction process. See, for example, Vitronics Corp. v. Conceptronic Inc. (90 F.3d 1576 (Fed. Cir. 1996)). A particularly interesting claim construction problem is carefully addressed in Pitney Bowes Inc. v. Hewlett-Packard Co., 51 USPQ 2d 1161 (Fed. Cir. 1999) wherein the Federal Circuit panel appears to have done a meticulous job of sifting out the two separate meanings for the term "spot" (or "spots") present in the written description, each of which was carried into a portion of the claims.
Markman is still recent enough that not all members of the Federal Circuit itself are entirely comfortable with the reoriented thinking that may be required to follow its mandate faithfully. The two original dissenters to the en banc Markman majority opinion were equally critical of the en banc majority opinion in their separate views expressed in Cybor v. FAS Technologies, Inc., 138 F.3d 1448 (Fed. Cir. 1998) (en banc), insofar as the majority reaffirmed that claim construction is to be addressed de novo on appeal, without affording deference to any alleged fact-findings purportedly made in the trial court claim construction process. To read many written opinions authored by these judges after Markman (and both before and after Cybor) is to recognize that they stand in the proverbial posture of "a man convinced against his will", forced to deal with Markman and Cybor but intellectually unconvinced of the merit of either. At times, other members of the Federal Circuit have likewise written opinions that seem to stray from either or both of the premises that patent claim interpretation is a question of law for the court and that a lower tribunal’s claim interpretation is to be reviewed de novo, without deference to the lower tribunal. Notwithstanding that some cases may have been wrongly decided under them, however, Markman and Cybor are clearly here to stay, and it behooves litigators to consider carefully how best to accommodate their mandates. The Daubert line of precedent from the Supreme Court has been only occasionally remarked by either the Federal Circuit or patent litigators but the impact, especially of Kumho Tire, likewise deserves their mutual thoughtful consideration.
Both Markman and its progeny and the Supreme Court’s Daubert line of cases, including Kumho Tire, suggest that the role of expert witnesses in patent litigation may require some rethinking on the part of patent litigators. A threshold question is whether the use of "patent" experts as a matter of course -- a practice much favored by many litigators, but frequently criticized by courts and, at times, by other patent litigators -- is likely to be widely accepted under the combined Markman-Daubert approach. Patent experts can be justified in some situations, of course, such as to fill the role of explaining the arcane niceties of administrative patent procedures or of giving an expert opinion upon whether a specific patent examiner acted reasonably with respect to a particular patent application or prior art reference in a specific instance. On the other hand, the use of such an expert to explain why there is or is not contended to be infringement of a patent -- i.e., to compare the accused product or process to the already court-interpreted patent claim, a question of fact -- may give rise to sustainable objection, even when only literal infringement is charged. It almost surely will do so if infringement under the doctrine of equivalents is in issue. Similarly, advancing a patent expert, rather than an expert in the technology field of the patent, at a Markman hearing, where the expert’s primary function has been held to be that of educating the trial judge about the technology so he or she can understand the patent and its file history, seems almost calculated to evoke strong objection that the testimony will be "unhelpful". At best, such testimony may appear to opponents and the trial judge to be an attempt at usurping the court’s function. At worst, it may be a wholly empty and time-consuming exercise.
Even technical experts may require more scrutiny than they have normally been given heretofore in U.S. patent litigation, where the emphasis in the past has more often been upon qualifying the proffered witness "as an expert" rather than upon the reliability of his or her opinion in a particular situation. Where a technical expert is advanced at a Markman hearing, primarily to educate the trial judge, the depth of his or her familiarity with the technological principles that underlie the invention may be a subject that deserves careful exploration at a prehearing deposition. This is particularly true when the "expert" is an employee of the party advancing his or her testimony, because corporate parties in the past have often deemed the mere possession of a Ph.D. degree in a technical field to equate to expert status in a patent proceeding. In addition, litigators should not scruple to inquire intensively into an expert’s familiarity with any patent he or she seeks to aid the trial judge in interpreting, including by determining how thoroughly the expert read the patent and whether only selected portions were addressed.
Where the expert has performed experiments or other work or directed that performance, has made special observations of accused products or processes or has otherwise engaged in preliminaries on which an "expert" opinion has been based with the intention of delivering it at trial, patent litigators need to make the same types of inquiries that tort litigators have long routinely made, to ascertain whether the opinion evidence to be given has any hallmarks of unreliability. And it should always be kept in mind that even a bona fide expert whose curriculum vita shows a solid base of training and experience in a particular field may nevertheless lack a reliable basis for a particular opinion to be offered in a particular patent case.
To sum up, Markman and its progeny to date in the area of patent claim interpretation, and Daubert (as extended by Kumho Tire) in all areas involving the use of experts in patent litigation, are developments in the law that deserve special thought and attention in preparing for every trial of a patent case to take place in the United States.
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