In a previous blog post, we discussed the Federal Circuit’s reluctance to relinquish control of claim construction after the Supreme Court’s Teva1 ruling as exemplified in the Enzo2 decision. The trend continues with the Federal Circuit’s decision in Teva on remand from the Supreme Court just last month. A divided panel still found the asserted claims, specifically the term “molecular weight,”3 indefinite and therefore invalid, reversing the district court.4 The Supreme Court in Tevaagreed with Teva that the Federal Circuit pecedent5 of reviewing all aspects of claim construction de novo is inconsistent with Fed. R. Civ. P. 52(a)(6), which provides that factual findings of the district court may only be set aside if “clearly erroneous.”6 The Court explained that claim construction is ultimately a question of law, but subsidiary factual findings must be given deference and reviewed under the “clear error” standard of review.7 Also, while Teva was pending, the Supreme Court issued the Nautilus II8 decision, which modified the Federal Circuit’s “insolubly ambiguous” standard for indefiniteness under 35 U.S.C. § 112, ¶2 to a more stringent “reasonable certainty” standard.9

The Federal Circuit on remand relied heavily on key phrases from the Supreme Court’s Teva decision in order to strategically classify the “factual findings” of the district court. First, the majority noted that the intrinsic evidence (claims, specification, prosecution history) is entitled to de novo review, whereas factual findings based on extrinsic evidence, such as expert testimony, receive deference under review for clear error.10 The majority clarified their view that only those things outside of the patent documents are factual in nature because “[t]he Supreme Court made clear that the factual components include ‘the background science or the meaning of a term in the relevant art during the relevant time period.’”11 Second, the majority seemed to warn that “[a] party cannot transform into a factual matter the internal coherence and context assessment of the patent simply by having an expert offer an opinion on it.”12

Based on this reasoning, the majority classified the factual findings of the district court very specifically, as “how a skilled artisan would understand the way in which SEC-generated chromatogram data reflects molecular weight.”13 Although the factual findings, which were based on expert testimony, were found not to be clearly erroneous, they did not resolve the meaning of the claim term, according to the majority.14

Turning then to the prosecution history of two continuations of the patent-in-suit,15 the majority noted that both received indefiniteness rejections because the term “molecular weight” was meaningless without more specificity.16 In response to this rejection in the first continuation, the applicants successfully argued that “[o]ne of ordinary skill in the art could understand that kilodalton units implies a weight average molecular weight, [Mw].”17 In response to a similar rejection in the second continuation, applicants successfully argued that a similar claim term meant “peak average molecular weight.”18

Caught in an apparent contradiction, Teva provided expert testimony that one of skill in the art would conclude the definition in the first continuation was scientifically erroneous because each measure of “molecular weight” could be expressed in kilodaltons.19 The majority parsed this as follows: the only factual finding was that a skilled artisan would understand that each type of “molecular weight” can be expressed in kilodaltons, but the legal conclusion is that a skilled artisan “would have understood that the applicants defined the term ‘molecular weight’ as Mw to gain allowance of the claims.”20

Thus, the majority concluded that the claim was invalid for indefiniteness “because read in light of the specification and the prosecution history, the patentee has failed to inform with reasonable certainty those skilled in the art about the scope of the invention.”21

Judge Mayer in his dissent criticized the majority for being “once again led astray by its failure to afford sufficient deference to the trial court’s findings of fact” due to “first embarking on an independent review of the record and then considering, as an afterthought, the important and carefully considered factual findings made by the trial court.”22 Judge Mayer’s criticisms seem to align with those of Judge Newman in her dissent in Enzo, where she argued that the majority ignored the factual determinations that the district court reached based on the “conflicting testimony [of the experts], along with concessions on cross-examination,” in disregard for the instruction in Teva.23

So far the Federal Circuit seems to remain reluctant to give deference to the district court even when the district court relies heavily on expert testimony.