Earlier this year, the Federal Circuit issued an opinion on claims construction that is of growing interest to IP litigators and patent prosecutors alike. According to the Federal Circuit, for a prosecution disclaimer to be found, the disavowing actions must be both clear and unmistakable. However, when the language is ambiguous, the Court must decline to find a prosecution disclaimer.
The case is Avid Tech., Inc. v. Harmonic, Inc., 812 F.3d 1040, 1042 (Fed. Cir. 2016). The lower court ruled that there was no patent infringement based on a narrow construction of claim language based in part by statements made during prosecution that the Court relied upon to narrow the claims. During prosecution, the patent lawyer distinguished prior art by asserting that “a central controller . . . identifies storage units that store the data and issues requests to storage units.” The trial court interpreted this disclaimer to have an “either or” function of “storing the data” or “issuing requests to storage units.” This construction resulted in a finding of no infringement.
The Federal Circuit disagreed with the claims construction. According to the Federal Circuit, the statement made during prosecution required the performance of both functions (identifying the storage and issuing requests). The take-away, however, is that the Federal Circuit held that, for a prosecution disclaimer to be found, the disavowing actions must be both clear and unmistakable. However, when the language is ambiguous, precedent requires that the Court decline to find a prosecution disclaimer.
This led to the conclusion that there was no clear and unmistakable disclaimer in the language used during the prosecution of the underlying patent. The District Court’s judgement was vacated and remanded for a new trial on infringement.