A statement made during prosecution may be used to define a claim term regardless of the scientific accuracy of that statement. Here, for example, in response to identical indefiniteness rejections in separate child applications regarding the claim term “molecular weight,” the patentee put forth conflicting definitions that ultimately rendered the claims of the parent application indefinite because the intended scope could not be reasonably certain, even though it was established that one of the conflicting definitions was scientifically erroneous. “Regardless of the scientific accuracy of the statement, a person of ordinary skill in the art would have understood that the applicants defined the term [term at issue] to gain allowance of the claims.” It may therefore be best ensure that statements made during prosecution are not only technically accurate but also consistent across patent families.
Background / Facts: The patents being asserted here and on remand from the Supreme Court relate to the drug Copaxone used in treating multiple sclerosis. The claims recite a range of values for a “molecular weight” without specifying the meaning of that term. The parties agree that “molecular weight” could refer to the peak average molecular weight (Mp), number average molecular weight (Mn), or weight average molecular weight (Mw). And they agree that each of these measures is calculated in a different way and would typically yield a different result for a given polymer sample. But the claim on its face offers no guidance on which measure of “molecular weight” the claims cover.
Issue(s): Whether—under the legal standards set forth in the Supreme Court’s Teva and Nautilus II decisions—the unqualified term “molecular weight” renders the asserted claims indefinite because it can refer to different measures, including Mp, Mw, and Mn, with significant variations in claim scope depending on which measure is construed.
Holding(s): Yes. In addition to the fact that the specification never defines “molecular weight” nor does this term have a plain meaning to one of skill in the art, the court noted that “[d]uring prosecution of the related [first and second child] 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.” Even though the court found “no clear error in the district court’s fact finding that one of the statements contained a scientifically erroneous claim,” the court refused to simply discredit that statement. “Regardless of the scientific accuracy of the statement, a person of ordinary skill in the art would have understood that the applicants defined the term ‘molecular weight’ as Mw to gain allowance of the claims. This is a legal conclusion unaffected by the scientific error made during prosecution.” Thus, ultimately, “[o]n this record, there is not reasonable certainty that molecular weight should be measured using Mp.”