Authored by Barry W. Graham
A Brief Recap of Markman
The last two years have been witness to the judicial reengineering of the whos and hows of claim interpretation in patent infringement litigation. The who is the trial judge; the hows include a number of factors, one being the use of extrinsic evidence—the focus of this article. This reengineering of claim interpretation is founded upon the landmark Markman v. Westview Instruments, Inc. decision in which the Federal Circuit established that claim construction is a matter of law and, thus, judges alone must construe patent claims before submitting the issue of infringement to a jury. 52 F.3d 967 (Fed. Cir. 1995), aff'd, 116 S. Ct. 1384 (1996). The Supreme Court, by affirming Markman, joined the Federal Circuit in ignoring past decades of U.S. patent infringement litigation in which juries had generally been relied upon to interpret claims or, at the very minimum, to answer fact questions relating to claim construction. See Markman v. Westview Instruments, Inc., 116 S. Ct. 1384 (1996).
Markman, in turn, has brought about several significant changes to patent litigation procedure, the most prevalent being the advent of the so-called "Markman hearing," a preliminary hearing held before an infringement jury trial, during which a judge receives evidence and rules on the proper construction of the claims. See, e.g., Loral Fairchild Corp. v. Victor Co. of Japan, Ltd., 906 F. Supp. 798 (E.D.N.Y. 1995) (Federal Circuit Judge Rader sitting by designation). Alternatively, some judges have opted to forgo such hearings and instruct juries on the proper construction of claims after receiving evidence on that issue at trial. See, e.g., Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576 (Fed. Cir. 1996). Since patent infringement suits are often won or lost based on how the claims are construed, a court's Markman findings are extremely significant to the litigation process.
Markman, however, accomplished more than just placing the burden of claim interpretation on the court. Most significantly, the Federal Circuit offered guidance as to how trial courts should construe patent claims. The Court, for example, directed trial judges to consider three primary sources in ascertaining the meaning of a patent claim: the claim language itself, the patent's specification, and the patent's administrative record in the U.S. Patent & Trademark Office, often referred to as the prosecution or file history. Markman, 52 F.3d at 979-80. These documents form the public record of the patent and constitute what the Court has termed the "intrinsic" evidence of claim meaning. Id.
In addition to intrinsic evidence, the Markman Court also permitted judges, at their discretion, to receive extrinsic evidence "'to aid the court in coming to a correct conclusion' as to the 'true meaning of the language employed' in the patent." Id. at 980 (quoting Seymour v. Osborne, 78 U.S. (11 Wall.) 516, 546 (1871)). Accordingly, extrinsic evidence, which is defined as "that evidence . . . external to the patent and file history, such as expert testimony, inventor testimony, dictionaries, and technical treatises and articles," id., may be "used for the court's understanding of the patent," but should not be used for "the purpose of varying or contradicting the terms of the claims." Id. at 981. Indeed, the Court specifically warned against using such evidence "for the purpose of clarifying ambiguity in claim terminology." Id. at 986.
In short, Markman instructed that while extrinsic evidence should never "enlarge, diminish or vary" the limitations of the claims, id. at 980, it may be used, for example, to explain or confirm the meaning of unfamiliar technical terms. Id. at 983. Such arguably vague directives, however, did little to shed light on the parameters trial courts should follow in utilizing extrinsic evidence in construing claims. Moreover, the Supreme Court's affirmation of Markman failed to offer any additional constructive support, instead opting to leave the development of such suitable parameters to the lower courts. Accordingly, the central issue on appeal in the wake of the Markman often related to the trial court's claim interpretation and use of extrinsic evidence. See Eastman Kodak Co. v. Goodyear Tire & Rubber Co., 114 F.3d 1547, 1552 (Fed. Cir. 1997).
Post-Markman Consideration of Extrinsic Evidence
The Federal Circuit's first significant post-Markman attempt to clarify the issue of whether it is appropriate for a trial court to consider extrinsic evidence in making a Markman finding is embodied in Vitronics Corp. v. Conceptronic, Inc. The Vitronics Court, in summary, severely restricted the use of extrinsic evidence by finding that reliance on such evidence is unnecessary, "and indeed improper," when the disputed terms of a claim can be understood from a careful reading of the public record, i.e., the intrinsic evidence. 90 F.3d at 1583. Indeed, "in most situations," the Court continued, "an analysis of the intrinsic evidence alone will resolve any ambiguity in a disputed term," and under those circumstances, "it is improper to rely on extrinsic evidence." Id.
Vitronics charged Conceptronic with infringement of a method used in the production of printed circuit boards. Id. at 1579. In presenting its argument for interpreting the claims, Vitronics relied heavily on the patent specification. Id. at 1580. Conceptronic, in contrast, relied on extrinsic evidence, including expert testimony, testimony of Vitronics' engineers, and a Vitronics memorandum. Id. The district court ultimately ruled in Conceptronic's favor. Id. at 1581.
The Federal Circuit, in reversing this ruling, outlined the strict guidelines pertaining to the consideration of extrinsic evidence summarized above and, more specifically, noted that "in interpreting an asserted claim, the court should look first to the intrinsic evidence of record, . . . [because it] is the most significant source of the legally operative meaning of disputed claim language." Id. at 1582. Although the Court further opined that "the specification is always highly relevant to the claim construction analysis," is usually dispositive, and "is the single best guide to the meaning of a disputed term," id., its ruling apparently is based on excluding the use of extrinsic evidence, at least in part, on basic underlying principles of fairness. See id. at 1583.
Most significantly, the Federal Circuit noted that it would be improper to rely on extrinsic evidence when an analysis of the intrinsic evidence alone resolves any ambiguity in the disputed claim terms because intrinsic evidence constitutes the public record of the patentee's claim, "a record on which the public is entitled to rely." Id. "In other words, competitors are entitled to review the public record, apply the established rules of claim construction, ascertain the scope of the patentee's claimed invention and, thus, design around the claimed invention." Id. Thus, it is imperative, the Court continued, that the public record not be altered or changed by extrinsic evidence introduced at trial. Id. To hold otherwise would render meaningless a competitor's right to rely on the public record for a determination of the scope of a patent's claims. Id.
With these principles in hand, the Federal Circuit held that the district court had impermissibly relied on extrinsic evidence to construe Vitronics' patent claims in favor of Conceptronic. "Only if there were still some genuine ambiguity in the claims, after consideration of all intrinsic evidence, should the lower court have resorted to extrinsic evidence . . . [to construe the claims]." Id. at 1584. Further, since the expert testimony in Vitronics was clearly inconsistent with the specification and file history, the testimony "should have been accorded no weight." Id.
Within a year of the Vitronics decision, the Federal Circuit again addressed the significance of extrinsic evidence in interpreting claims in Eastman Kodak Co. v. Goodyear Tire & Rubber Co., a post-Markman decision that was significant for several reasons. Firstly, by virtue of the trial court's Markman claim construction, 80% of the allegedly infringing production lines were found to be noninfringing as a matter of law and, in turn, never even made it to the jury. Eastman Kodak, 114 F.3d at 1559-61. Secondly, the Federal Circuit was divided on the issue of whether extrinsic evidence had been properly considered in interpreting the claims.
In citing both Markman and Vitronics, the Court, in a split decision, confirmed the trial court's use of extrinsic evidence "to learn the necessary context for understanding the claim language," noting that courts "may consult other sources, including the patent specification, the administrative record of patent acquisition, expert commentary from those of skill in the art, and other relevant extrinsic evidence." 114 F.3d at 1552. The Court cautioned, however, that the specification, prosecution history, and other relevant evidence are not be accorded the same weight as the claims themselves and may only be consulted when necessary to explain the context of the claim language. Id.
In Eastman Kodak, the Court concluded that the disputed claims and related specification did not provide conclusive proof of claim meaning, which justified looking to other sources to discern the meaning of the claim language. Id. at 1555. Indeed, the Court noted that when the claim language alone fails to settle all claim interpretation issues, judges may consult other sources. Id. at 1554. (citing E.I. Du Pont De Nemours & Co. v. Phillips Petroleum Co., 849 F.2d 1430, 1433 (Fed. Cir. 1988)). The Court, in turn, first considered the prosecution history, and upon finding that it too was inconclusive, concluded that the district court had properly consulted extrinsic evidence relevant to claim meaning. 114 F.3d at 1555.
As a general rule, the Court continued, the construing court interprets words in a claim as one of skill in the art at the time of the invention would understand them. Id. (citing Intellicall, Inc. v. Phonometrics, Inc., 952 F.2d 1384, 1387 (Fed. Cir. 1992)). Thus, under these particular circumstances, the testimony of one skilled in the art about the meaning of claim terms at the time of the invention will almost always qualify as relevant extrinsic evidence. Markman, 52 F.3d at 981.
The Court qualified these findings as being entirely consistent with Vitronics by suggesting that "if, of course, the meaning of the claims is clear from their language in view of the context provided by the specification and the prosecution history, the trial court should limit its consideration of extrinsic evidence." Eastman Kodak, 114 F.3d at 1555 (citing Vitronics, 90 F.3d at 1583). Extrinsic evidence, the Court continued, "whether providing context for the claims or explaining claim meaning to one of skill in the art—cannot contradict claim language." 114 F.3d at 1555.
The dissent in Eastman Kodak, however, unambiguously stated that "while correctly quoting the rule [spelled out in Vitronics], the majority misapplies it." Id. at 1562. The disputed claim, the Dissent continued, "is clear on its face, when read in light of the specification . . . ." Id. at 1561. Accordingly, "the court erred in its instruction to the jury concerning the meaning of the claim and in permitting the jury to rely on [extrinsic evidence]." Id. Indeed, the dissent strongly opined that "one must read and rely on the specification, not invent categories of activities to which witnesses can [contradict the specification]." Id. at 1563. It, therefore, remains to be determined how closely the directives laid out in Vitronics and its progeny will actually be followed.
Potential Pitfalls to Consider
In conclusion, even the Federal Circuit has found it necessary to consult extrinsic materials such as dictionaries, technical reference works, and expert testimony in construing claims in this post-Markman era. Markman, Vitronics, and their progeny, however, clearly disfavor, in theory, the use of such evidence and, in particular, the use of expert testimony in making Markman findings unless a "genuine ambiguity" exists in the claims that absolutely cannot be "understood from a careful reading of the public record" and/or the court is having difficulty understanding the claimed technology. E.g., Vitronics, 90 F.3d at 1584.
Such restrictive limitations on the use of extrinsic evidence should, in turn, not only act as a warning to practitioners who have traditionally relied upon expert testimony, but also highlight the importance of clear patent drafting. For one, reliance can no longer be placed with confidence on what those skilled in the art would likely understand. Accordingly, patent drafters should take care to eliminate any potential ambiguity in claim terms by defining, in the specification, any term that may not be absolutely clear on its face. Indeed, it may now be advisable to err on the side of providing more detailed definitions of critical terms that otherwise could conceivably be given an adverse "ordinary usage" interpretation by a judge. Moreover, what is most important to recognize in drafting a patent is that evidence of the inventor's intended meaning of a word may be irrelevant unless that intention is clearly stated in the patent specification itself.
Postscript: The Vitronics decision, in particular, additionally forewarns trial counsel of potential pitfalls he or she may encounter if a judge waits to construe the patent's claims until conclusion of evidence at trial. Indeed, such a late construction may require patentee's counsel to present evidence on infringement and the accused infringer's counsel to defend against infringement under both partyies interpretation of the claims. Otherwise, the patentee may be forced to concede noninfringement, as was the case in Vitronics, because he or she failed to present infringement evidence consistent with the claim construction sought by the accused infringer and accepted by the court. Similarly, the accused infringer may be forced to concede infringement if evidence in defense of the interpretation ultimately accepted by the trial court has not been presented. However, since a court may still adopt an interpretation of the claims that neither party has advocated, see, e.g., Maxwell v. J. Baker, Inc., 86 F.3d 1098 (Fed. Cir. 1996), counsel for both parties should consider seeking a Markman hearing and issuance of an order construing claims before the introduction of evidence at trial.
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