Qualification of Expert Witnesses in United States Patent Litigation: A Review of Federal Circuit Case Law Regarding Rule 702 of the Federal Rules of Evidence

Abstract

Expert witnesses serve an important role in United States patent litigation. Patent litigation often involves complex technological issues. Technical experts are needed to help a judge interpret claim language or to assist a jury to understand patented technology or infringing products. When resolving the patentability issues, such as anticipation and obviousness, technical experts are good consultants for factfinders. Additionally, damages calculation requires knowledge of industries and financial or accounting theories. Damages experts must get in to resolve the issues of monetary remedies. While expert witnesses play an important role in patent litigation, fewer studies explore the relevant case law about the qualification of experts or the admissibility of expert opinions. So, this paper is intended to address Federal Circuit case law regarding those issues. While Title 35 of the United States Code speaks nothing about expert witnesses, Rule 702 of the Federal Rules of Evidence is the only statutory basis for the requirements of qualified experts. In this paper, the case law review begins by examining the judicial interpretation of Rule 702. Three U.S. Supreme Court cases and several Federal Circuit cases will be analyzed. Then, this paper focuses on two categories of experts: technical experts and damages experts. Cases related to either category will be discussed. While Rule 702 requires an expert to have “scientific, technical, or other specialized knowledge,” it is opt to a district court judge to admit or exclude expert witnesses or expert opinions as evidence heard by a jury. Besides, the Federal Circuit’s review standard is an abuse of discretion. So, a district court judge usually has much leeway. Furthermore, based on the analysis of the Federal Circuit cases, this article provides legal principles or propositions related to expert testimony.

專家證人在美國專利訴訟中扮演重要的角色。專利訴訟常涉及技術議 題，需要技術專家的參與來幫助解釋請求項或協助陪審團瞭解專利技術或侵權物。當處理可專利性爭點時，技術專家則是事實認定者很好的顧問。此外，賠償金計算需要產業或財務會計理論等知識。賠償金專家必須參與，以能讓金錢式賠償的爭議得以處理。雖然專家證人的角色重要，但對相關判例法的研究不是很多，特別是針對證人資格或證詞採納等議題。因此，本文在探討巡迴上訴法院針對該類議題之判例。美國專利法並無著墨專家證人之規範，而相關議題主要是聯邦證據規則第 702 條所主導。在本文中，首先分析與第 702 條解釋有關之司法意見，包括三件聯邦最高法院判決和幾件巡迴上訴法院判決。接著，本文著重在討論二類專家證人（技術專家和賠償金專家）之相關判決。第 702 條要求專家必須具有「科學的、技術的、或特殊的知識」，但由地方法院的法官來裁定是否要准予或排除專家證人或意見作為證據。此外，對於地院的裁定，巡迴上訴法院的審查基準是「裁量權之濫用」。因而，地院法官有很大的裁量空間。本文亦對相關判決進行分析，並整理相關法理原則。