In TEVA PHARMACEUTICALS USA, INC. v. SANDOZ, INC., Appeal Nos. 2012-1567, 2012-1568, 2012-1569, 2012-1570, on remand from the Supreme Court, the Federal Circuit again held the challenged claims to be indefinite because the claims, specification, and prosecution history do not convey with reasonable certainty the measure of molecular weight to be used, even after a finding that the district court’s factual determinations were not clearly erroneous.

Sandoz submitted ANDAs for generic versions of one of Teva’s branded drugs. Teva sued for patent infringement.  The relevant claim recited a method of manufacturing a compound having a “molecular weight” within a specified range.  There are three different measures of molecular weight: peak average, number average, and weight average, each having a different value.  The district court held that the claim was sufficiently definite, and the Federal Circuit reversed.  The Supreme Court vacated the Federal Circuit decision, holding that, while it is proper to treat the ultimate question of the proper construction as a question of law, subsidiary factual findings should be reviewed for clear error.  The Supreme Court remanded to the Federal Circuit.

On remand, the Federal Circuit concluded that the claims, specification, and prosecution history do not convey with reasonable certainty the measure of molecular weight to be used.  The Federal Circuit, after noting that the district court’s factual determinations were not clearly erroneous, concluded that the factual determinations do not resolve the ambiguity in the claims about the intended molecular weight measure.  The Federal Circuit noted that, in one continuation patent, the applicant overcame an indefiniteness rejection by indicating that a weight average molecular weight should be used, and in another continuation patent, the applicant overcame a similar rejection by stating that a peak average molecular weight was to be used.  Based on the lack of guidance as to “molecular weight” in the claims or the specification and based on the inconsistency in the prosecution history of the continuation patents, the Federal Circuit concluded that the claim is invalid for indefiniteness.

In dissent, Judge Mayer argued that a single statement in the prosecution history of a continuation application should not be dispositive on the question of whether the asserted patent is sufficiently definite, especially when the trial court has determined a person of ordinary skill in the art would not have relied on the statement based on its scientific inaccuracy.