In a recent blog post, we reported that a divided U.S. Court of Appeals for the Federal Circuit (CAFC) had reaffirmed that appellate review of patent claim interpretations is de novo, without any deference to the trial court even for factual matters. As we stated in that post, the 6-4 en banc decision by the CAFC in Lighting Ballast Control LLC v. Philips Electronics N.A. Corp.,1 appeared to be an open invitation for the U.S. Supreme Court to take up the issue.

The Supreme Court has now accepted that invitation, albeit with a difference dance partner. On March 31, 2014, the Supreme Court granted certiorari in Teva Pharmaceuticals USA, Inc. v. Sandoz Inc., on the following issue:

Whether a district court’s factual finding in support of its construction of a patent claim term may be reviewed de novo, as the Federal Circuit requires (and as the panel explicitly did in this case), or only for clear error, as Rule 52(a) requires.

Teva Pharmaceuticals USA, Inc. v. Sandoz Inc. concerns Teva’s Copaxone drug used to treat multiple sclerosis. Sandoz sought to introduce a generic version of Copaxone, and challenged the validity and scope of nine Teva patents related to the Copaxone product. The trial court held that the patents were valid and would be infringed by Sandoz’s generic version of Copaxone. 876 F. Supp. 2d 295 (S.D.N.Y. 2012).

The CAFC reversed the trial court in part, holding that some of the asserted patent claims are invalid. 723 F.3d 1363 (Fed. Cir. 2013). In doing so, the CAFC disagreed with the trial court’s interpretation of “molecular weight.” While the trial court construed “molecular weight” in the patent claims to refer to the peak average molecular weight of the claimed synthetic polypeptide, the CAFC panel held that the term “molecular weight” was ambiguous. Because of this ambiguity, the claims were indefinite and therefore invalid.

In analyzing the meaning of the term “molecular weight” in the context of the asserted claims, the CAFC noted that a polymeric material such as the claimed polypeptide “typically consists of a mixture of individual polymer molecules that have varying molecular weights.” 723 F.3d at 1367. The CAFC noted that there are several different ways to define the molecular weight of such a polymeric material, including the peak average molecular weight (Mp), the number average molecular weight (Mn), and the weight average molecular weight (Mw):

“Mp is the molecular weight of the most abundant molecule in the sample. Mn is the arithmetic mean, or the total mass of all the molecules in the sample divided by the total number of molecules. Mw is still another average molecular weight measure that is calculated differently from Mp and Mn. In a typical polymer sample, Mp, Mn, and Mw have different values.”

The trial court construed “molecular weight” to refer to the peak average molecular weight (Mp), and therefore this claim term was not ambiguous. The CAFC disagreed, stating that the claims in question “contain an ambiguity because their plain language does not indicate which average molecular weight measure is intended.” Id. at 1369. The court noted that statements made during prosecution of two of the patents in suit were directly contradictory. Teva argued during prosecution of one of the patents in suit that “[o]ne of ordinary skill in the art, upon reviewing the specification, would understand that ‘average molecular weight’ refers to the molecular weight at the peak of the molecular weight distribution curve.”

During prosecution of another of the patents in suit, Teva argued that “[o]ne of ordinary skill in the art could understand that kilodalton units implies [sic] a weight average molecular weight.” Id. Despite the testimony from Teva’s expert witness that one skilled in the art would know that the claim term “molecular weight” meant Mp, the CAFC held that this claim term was “insolubly ambiguous.”

Though the claim construction issue in Teva relates to whether the meaning of a claim term is insolubly ambiguous, the issue is the same one addressed in Lighting Ballast Control LLC v. Philips Electronics N.A. Corp.: is appellate review of a trial court’s claim construction strictly de novo, without any deference to any underlying factual determinations by the trial court? Alternatively, was Judge O’Malley correct in her dissent in Lighting Ballast when she stated: “[w]hen a district court makes fact-findings needed to resolve claim construction disputes, Rule 52(a) requires us to defer to those findings unless they are clearly erroneous.”

The Supreme Court will not hear this case until at least October, with a decision unlikely until at least December.


12014 U.S. App. LEXIS 3176, decided Feb. 21, 2014.