In Integra Lifesciences v. Hyperbranch Medical Technology, the Defendant took the position that the term "molecular weight" in the claims of U.S. Patent 6,566,406 was indefinite:
1. A method for preparing a biocompatible crosslinked polymer hydrogel, comprising: providing a biocompatible small molecule crosslinker with a molecular weight of 2000 or less, the crosslinker having n crosslinker functional groups, wherein n is two or more, and wherein the crosslinker functional groups are either electrophilic or nucleophilic; providing a synthetic biocompatible functional polymer with a molecular weight of at least about 7 times more than the crosslinker. . .
It was undisputed that, when determining the molecular weight of a polymer, different
statistical measures could be used and that these would yield different numerical values for a given polymer. Defendant relied heavily on the decision of the United States Court of Appeals for the Federal Circuit in Teva Pharms. USA, Inc. v. Sandoz, Inc., 789 F.3d 1335 (Fed. Cir. 2015) in support of its argument, a case that analyzed indefiniteness with respect to the same term. In Teva, the Federal Circuit held that:
[I]t is undisputed that "molecular weight" or average molecular weight can be ascertained by any of three possible measures: Mp, Mn, and Mw. The claims do not indicate which measure to use. The specification never defines molecular weight or even mentions Mp, Mw, or Mn. And the term "average molecular weight" does not have a plain meaning to one of skill in the art .... During prosecution of the related patents, which with respect to molecular weight have identical specifications, examiners twice rejected the term "molecular weight" as indefinite for failing to disclose which measure of molecular weight to use (Mp, Mn, or Mw). And the patentee in one instance stated that it was Mw and in the other stated it was Mp . ... We hold that claim 1 is invalid for indefiniteness by clear and convincing evidence 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. On this record, there is not reasonable certainty that molecular weight should be measured using Mp.
In this case, the magistrate judge also found that the claim term “molecular weight” was indefinite:
The claims and the specification of the '406 patent do not directly speak to this issue at all. Nor is the Court persuaded that the POSITA would follow [the patentee’s expert’s] 9-step pathway to "Mn" in order to fill in the gap. That pathway relies in significant part on a single citation in the later-issued '705 patent to the Aldrich Catalog. And that very citation, on its face, does not direct anyone to consult the Aldrich Catalog for purposes of assessing measurements of molecular weight. Even if one did turn to the Aldrich Catalog for this purpose, the catalog does nothing to clearly indicate what measurement should be used; instead, it makes reference to different types of molecular weight measurements, a fact that would only solidify a POSITA's uncertainty. All of this, along with Dr. Mays' tendency to cherry-pick (without explanation) which portions of the Aldrich Catalog a POSITA would look to in the first place, renders the outcome here clear. See Butamax Advanced Biofuels, LLC v. Gevo, Inc., 117 F. Supp. 3d 632, 641 (D. Del. 2015) (finding claim indefinite where various methods could have been used to make the calculation called for by the claim limitation at issue, and "[b]ased on the broad and ambiguous language of the specification, the court does not find commonsensible [the expert's] conclusory assertion that a [POSITA] would be directed by the specification to use the MegAlign program (and its online help manual not referred to in the specification)" to do so). The Court agrees with Defendant that this case is similar to Teva, and that the conclusion reached here should be the same as the conclusion the Federal Circuit reached in that case.