In Microsoft Corp., v. Proxyconn, Inc., the U.S. Court of Appeals for the Federal Circuit recognized that there are limits to the broadest reasonable interpretation standard, and explained, “[t]hat is not to say, however, that the Board may construe claims during [inter partes review] so broadly that its constructions are unreasonable under general claim construction principles.” Particularly instructive was the Court’s statement that in addition to the specification, the Patent Trial and Appeal Board (PTAB or Board) should “consult the patent’s prosecution history” when giving claims their broadest reasonable interpretation. Relying on these principles, the Federal Circuit vacated several of the Board’s unpatentability determinations on the basis that the claim constructions were “unreasonably broad,” reversed in part and remanded “for further proceedings” consistent with its opinion.

On this, the first remand back to the PTAB from a post-grant final decision,  the PTAB agreed with the petitioner and ordered additional briefing on “the effect of the Federal Circuit’s . . . decision on our Final Written Decision” and further ordered that “no new prior art references or other evidence shall be presented by either party.”  The regulations and the Practice Guide are silent on the procedure to be utilized on remand. The petitioner proposed limited additional briefing on the effect of the Federal Circuit’s claim construction rulings. The patent owner suggested that additional briefing was unnecessary. Microsoft Corp. v. Proxyconn, Inc., IPR2012-00026/IPR2013-00109, (PTAB, Dec. 9, 2015) (Giannetti, APJ).

In the second final written decision, the PTAB concluded that the claims still were invalid under the more narrow constructions from the Federal Circuit, in some instances on obviousness grounds rather than for anticipation as initially found.  The claim constructions provided by the Federal Circuit corresponded to the “claim constructions provided by” the patent owner” during the PTAB proceeding. As a result, the PTAB rejected the patent owner’s argument that reconsidering the merits of the case on remand resulted in unfairness or a denial of due process.

Practice Note: Although this decision provides guidance on what the PTAB is likely to do on remand from a post-grant proceeding, there are still many questions unanswered with respect to the treatment of future cases. For example, it is unclear what the PTAB will do where the Federal Circuit adopts a claim construction that was not proposed in the original trial. In such a case, it might be necessary to re-open discovery.