Actelion – Significant Digits of a Claimed Numerical Value – Is It Significant Enough?
The United States Court of Appeals for the Federal Circuit recently vacated a district court’s decision regarding the interpretation of claimed term “pH of 13 or higher,” and remanded to the district court for consideration of the parties’ provided extrinsic evidence. The Actelion decision is an important reminder that the way a numerical range is presented is of key importance to how it will be construed.
Claim terms are given their plain, ordinary, and customary meanings, unless a sufficiently clear definition of a term that is different from its ordinary and customary meaning is included in the specification. Actelion Pharmaceutical Ltd v. Mylan Pharmaceuticals Inc.[1] reminds us that unambiguous claim terms and a specification which provides clear and consistent definitions of such terms are paramount in properly establishing the boundaries of claimed invention, even when the claimed subject matter includes numerical values and ranges.
In Actelion, the United States Court of Appeals for Federal Circuit (CAFC) vacated a district court’s decision holding that the claim term “pH of 13 or higher” is to be construed in accordance with its plain and ordinary meaning, and then holding that pH of 12.5 rounds up to 13 and thus meets the claim limitation, as proposed by Actelion. The CAFC stated that the district court adopted Actelion’s proposed construction based on the intrinsic record alone – without any inquiry into the understanding of the “plain and ordinary meaning” by a person of ordinary skill in the art (“POSITA”). Thus, the CAFC remanded the case back to the district court for consideration of the extrinsic evidence submitted by the parties and its impact on the claim construction.
Actelion owns U.S. Patent Nos. 8,318,802 and 8,598,227, which are directed to epoprostenol formulations. The claimed lyophilizate is formed from a bulk solution, and the bulk solution has a pH of 13 or higher. Mylan sought approval to manufacture and sell epoprostenol, and Actelion responded by filing an infringement suit against Mylan. The district court decided that the ordinary rule of rounding would be applied to the claim term “pH of 13 or higher,” meaning that it would include a pH of 12.5 or higher. Accordingly, the district court concluded that Mylan’s solution having pH of 12.5 infringed Actelion’s patents. The district court stated that such decision was reached “after considering the claims, the entirety of the specifications of the patents-in-suit, and the prosecution history,” i.e., all of the intrinsic evidence. Mylan appealed.
While there is no need to consult extrinsic evidence when the intrinsic evidence unambiguously provides or supports a claim interpretation, it is appropriate to consider extrinsic evidence to construe the claim if there is any ambiguity in the meaning of a claim term after considering the intrinsic evidence.
In evaluating the claim language itself, the CAFC noted that there is no blanket rule that open-ended ranges must foreclose rounding. The Court declined to create a “bright-line” rule that language such as “precisely” or “exactly” is always needed to avoid rounding, or that the lack of approximation language, such as “about,” always dictates a precise value. Instead, the CAFC found both views equally plausible: “that the absence of approximation language might suggest no approximation, but that the nature of measuring a pH value might nonetheless reasonably require a margin of error.” Instead, the CAFC emphasized that the lower limit of 13 must be taken in the context of what it represents – pH – and whether this context impacts the claim meaning with respect to precision of measurement, significant digits, or rounding.
Turning to the specification, the CAFC noted that the scope of the claim remained unclear after consulting the specification because the specification inconsistently described the level of specificity for a pH of 13 (for example, the specification recites a preferred pH of 12.5-13.5, and in using both 13 and 13.0, uses varying levels of precision). Finally, in considering the prosecution history, the Court further stated that the Examiner drew a distinction between the stability of a composition with a pH of 13 and that of 12, but such distinction does not provide guidance whether the pH of 13 could encompass values that round to 13, such as 12.5. The CAFC concluded that in this case, the claim cannot be construed without the aid of extrinsic evidence, even though the plain and ordinary meaning will apply. The district court did not address such extrinsic evidence including textbooks, which are highly relevant, to explain how a POSITA would understand the significant digits for a pH value. That is, because the intrinsic evidence “supplies the same clarity as to the desired level of precision as muddied water,” the district court should have looked, at a minimum, to the textbook excerpts offered and addressed by both parties to construe the claims.
The outcome of Actelion highlights the risks particularly associated with inconsistent language within the specification, which is considered the “single best guide to the meaning of a disputed term.” Had the specification been consistent in its use of significant figures when describing the pH range, it is possible the intrinsic evidence alone would have unambiguously supported a single, correct claim construction. Moreover, while the CAFC would not adopt a bright-line rule that the absence of “about” dictates a precise value, it is clear that had the claim recited “pH of about 13 or higher,” at least some amount of rounding would be included. These are important considerations for the patent drafter and prosecutor alike.
