In MaxLinear Inc. v. CF Crespe LLC the Federal Circuit ruled that the PTAB did not address arguments concerning patentability of certain dependent claims of the patent at issue separate from the corresponding independent claims, and vacated and remanded the PTAB’s final written decision.

MaxLinear initially petitioned the PTAB for an inter partes review of U.S. Patent No. 7,075,585 (“the ’585 patent”), assigned to Crespe and directed to a broadband television signal receiver that includes a multi-standard channel filter. The PTAB instituted review of claims 1-4, 6-9, and 16-21 of the ’585 patent based on a combination of certain prior art references (IPR2015-00592; “the ’592 IPR”). In its final written decision, the PTAB held that none of the challenged claims was shown to be unpatenable over the prior art references. Notably, the PTAB limited its analysis to independent claims 1 and 17 without a separate analysis or discussion of the dependent claims, and concluded that MaxLinear did not show, by a preponderance of the evidence, that the dependent claims are unpatentable. MaxLinear appealed the final written decision.

During pendency of the appeal at hand, the Federal Circuit decided appeals of two separate IPRs (including IPR2014-00728 (“the ’728 IPR”)) challenging the same ’585 patent. In both cases, the court affirmed the PTAB final written decisions canceling independent claims 1 and 17 and dependent claims 2, 3, 5, 10, 16, and 18-20 as unpatenable over a combination of prior art references different from that used in the ’592 IPR. Noting the preclusive effect of these prior decisions as a matter of collateral estoppel, the court determined in the appeal of the ’592 IPR that claims 1 and 17 were already determined to be unpatentable, and held that the sole remaining issue was whether the remaining claims not addressed in the separate IPRs (dependent claims 4, 6-9, and 21) are unpatentable.

The court vacated the PTAB’s decision in the ’592 IPR because “the patentability of claims 1 and 17 was the sole basis for the Board’s decision in this IPR, and the Board has not separately addressed the dependent claims.” On remand, the PTAB must consider whether dependent claims 4, 6-9, and 21 can survive the unpatentability of independent claims 1 and 17 in view of the prior art cited in the ’728 IPR, and specifically whether these dependent claims “present materially different issues that alter the question of patentability, making them patentably distinct from claims 1 and 17.”

In view of the court’s decision, patent owners should make efforts during an IPR to argue that challenged dependent claims are separately patentable over their independent claims, especially because the court here instructed the PTAB to consider whether such arguments were waived in the IPR at hand.