Nearly 20 years ago, the Supreme Court (in Markman v. Westview Instruments) considered whether the construction of a patent claim during litigation is a matter of law reserved entirely for a federal court judge, or subject to a Seventh Amendment guarantee that a jury undertake that exercise. The Court unanimously held “that the construction of a patent, including terms of art within its claim, is exclusively within the province of the court.” District courts have followed that holding by conducting hearings (in the absence of juries) in which the litigants may present factual evidence and expert testimony, and weighing that evidence in view of the litigants’ arguments before construing claims for trial of infringement and invalidity.
Shortly after the Court’s unanimous holding, a divided en banc panel of the Court of Appeals for the Federal Circuit (in Cybor Corp. v. FAS Technologies, Inc.) concluded that a district court’s claim construction must be reviewed, on appeal, for correctness as a matter of law (de novo). And, in late February 2014, a different, divided en banc panel of the Federal Circuit (in Lighting Ballast Control LLC v. Philips Electronics North America Corp.) confirmed the propriety of the Cybor standard of appellate review and refused to replace that standard with one that would offer deference to a district court’s claim construction.
Interpretation of a patent through claim construction is practically no different than interpretation of sentences in any other legal document (e.g., statutes, contracts, etc.), which is subject to de novo standard of review. That review standard applies in many situations outside of patent litigation, where a district court must interpret facts, often animated by expert testimony. For example, interpretive issues of contracts and statutes are reviewed de novo on appeal, even if the district court must weigh competing expert testimony on the subject. Claim construction may well be less fact-intensive than contract- or statutory-interpretation. The latter two entertain factual consideration of the contracting parties’ or legislature’s intent. In claim construction, however, the patentee’s intent is of no import and, instead, the objectivity of the ordinarily-skilled artisan is key.
There is no doubt that the definitions of the artisan and the art are among the factual determinations that underlie the construction just as they underlie certain legal conclusions of patent validity (e.g., obviousness, enablement). But, there is minimal (if any practical) conflict between the de novo standard of review for claim construction and a deferential standard of review of the most pertinent factual issues underlying determinations of patent validity. When trying validity, the most pertinent questions are of historical fact — i.e., as of the patent’s filing date what did the ordinarily-skilled artisan know, or could that artisan have practiced the invention based on what the patent teaches? — and the answers are precisely the type for which deference is likely suitable. And, if there is a conflict, then practically a circuit judge is just as capable of resolving the fact as a district judge.