The claims of a patent define the scope of the exclusive right granted to the patentee. Claims should be written such that a person of ordinary skill in the art can understand the boundaries of the invention. The language, which can sometimes be ambiguous, typically consists of a mix of ordinary languages as well as technical and legal jargon. Thus, an important step for courts, in resolving patent infringement disputes, is the interpretation of the patent claims in a proceeding called the “Markman hearing.” The court’s interpretation of the patent claims, called claim construction, can provide more clarity regarding the likely outcome of a patent infringement case and help promote settlements.
As the United States Supreme Court held in Markman, claim construction is “exclusively within the province of the court.” To construe patent claims, judges examine the words of the claim, the patent specification, and the prosecution history. Judges are permitted to consider “extrinsic evidence” such as dictionaries, treatises, or expert testimony. Extrinsic evidence is usually considered less reliable than the “intrinsic” patent specification and prosecution history.
Prior to the recent Teva decision, the issue of claim construction, including both the intrinsic and extrinsic evidence used, was viewed entirely as a question of law subject to de novo review on appeal. However, in Teva, the United States Supreme Court ruled that the underlying factual findings in claim construction at the district court level are subject to a more deferential clear error standard. Thus, if district court’s claim interpretation relied on intrinsic evidence alone, it is an exclusively legal determination subject to de novo review. However, if the district court relied on extrinsic evidence to help define the claim language, these factual findings are subject to the clear error standard.
Before Teva, legal scholars contended that the de novo review of claim construction incentivizes district courts to downplay their reliance on expert testimony and factual findings in order to avoid reversal. Now that Teva has created greater deference to factual findings at the district court level, commentators predict a shift in how claim construction is litigated. There could be an incentive for litigants to create factual issues in claim construction. This could increase the cost of claim construction because litigants are encouraged to introduce extrinsic evidence such as expert testimony. Additionally, in light of the heightened deference, district court judges may rely more heavily on factual issues in writing their opinions in order to reduce the probability of being reversed on appeal. Of course members of the legal community disagree about the ultimate implications of the decision. Some predict that the deference to factual findings on appeal will result in the Federal Circuit upholding some claim constructions that would otherwise have been overturned under the old de novo standard. Other commentators believe that the decision will not make a significant difference because claim construction still requires legal analysis.
Two recent cases at the district court and Federal Circuit level may shed some light on how these courts will approach claim construction and claim construction appeals in light of Teva. In Shire Development, LLC v. Mylan Pharmaceuticals, Inc., the District Court for the Middle District of Florida denied the plaintiff’s request for supplemental briefing on claim construction in light of Teva, citing that the claim construction was based only on intrinsic evidence. This could suggest that district courts will be careful in relying on extrinsic evidence in construing claims despite the increased deference to these factual findings post-Teva.
In the Federal Circuit, Teva‘s impact is also unclear. In the recent case, Enzo Biochem Inc. v. Applera Corp., the panel majority reversed the district court’s claim construction because the expert testimony on which the district court relied did not override the intrinsic evidence on which the majority based its interpretation. In reversing the district court’s claim interpretation, the Federal Circuit shows that the introduction of extrinsic evidence into the record may not do much work in protecting district court judges from reversal. In fact, the Federal Circuit could find that the intrinsic evidence is clear enough by itself to interpret a given claim and that extrinsic evidence is unnecessary. Despite this holding, there may be hope for litigants and district courts seeking to rely more heavily on extrinsic evidence in claim construction. Judge Newman, in her dissent, criticized the majority for failing to show error in the district court’s factual findings.
Although Teva ostensibly raises the deference for factual findings in claim construction, in light of the cases discussed above, the use of factual findings in claim construction still seem limited. However, only time will tell whether or not this is actually the case.