The US Court of Appeals for the Federal Circuit concluded that the Patent Trial & Appeal Board’s use of a reference that was not urged by the petitioner in an inter partes review (IPR) petition was harmless since the Court agreed with the Board’s analysis and conclusion that all challenged claims were unpatentable as obvious on alternative grounds raised in the petition. Netlist, Inc. v. Micron Technology, Inc., Case No. 2024-1707 (Fed. Cir. Sept. 2, 2026) (Reyna, Linn, Stark, JJ.)

Netlist owns a patent directed to improving the performance and memory capacity of memory boards. The patent describes using buffers between a memory controller and memory devices. Those buffers contain data paths that can be selectively enabled during read and write operations. Samsung filed a petition for IPR challenging certain claims of the patent as obvious over the combination of two prior art patents, Ellsberry and Halbert. The Board instituted review and determined that Samsung met its burden to show that the challenged claims were obvious over Ellsberry alone or in combination with Halbert. Netlist appealed.

The Federal Circuit reviewed the Board’s decision for compliance with the Administrative Procedure Act (APA) and agreed with the Board’s technical review of the prior art in finding the challenged claims obvious. The APA requires that a Board decision identify the reasons and bases in the record for reaching its conclusions. In an IPR proceeding, this generally requires the Board to proceed in accordance or conformance with the challenge grounds presented in the IPR petition, and the Board may not “depart from the petition and institute a different IPR of its own design.” In the past, the Federal Circuit has found error where the Board held claims unpatentable based on grounds that were not urged by the IPR petitioner.

Netlist argued that even if the Board had substantial evidence to find that Ellsberry taught most limitations at issue, the Board erred by using a Netlist patent in its analysis to fill a gap in terms of a claimed limitation. The Board cited the Netlist patent for its teaching that an additional clock cycle could account for delay as data traveled through a buffer. Netlist argued that it was improper to use the Netlist patent to supply a teaching of a claim limitation when Samsung did not present this reference as an invalidity ground in its IPR petition. Netlist argued that the Board expanded the role of the Netlist patent from being mere evidence of general skill in the art to that of a prior art reference in violation of the APA restriction against departing from the petition to find claims invalid on grounds of “its own design.”

The Federal Circuit concluded that any potential error arising from the Board’s use of the Netlist patent was harmless since the Board found alternatively that Ellsbery alone without relying on the Netlist patent taught the limitations in the challenged claims.

Practice note: The decision leaves unresolved when the Board’s use of a reference not relied on in the [...]

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