Addressing the Patent Trial and Appeal Board’s (PTAB’s) final determination in an inter partes re-examination, the US Court of Appeals for the Federal Circuit reversed the PTAB’s determination that some claims were supported by the written description where the PTAB improperly altered the claim construction in connection with its written description analysis. The Federal Circuit found that under the proper construction, the record lacked substantial evidence to find written description support for the claims. Cisco Sys., Inc. v. Cirrex Sys., LLC, Case Nos. 16-1143; -1144 (Fed. Cir., May 10, 2017) (Chen, J). In addition, the appellant cross-appealed the PTAB’s determination that the remaining claims lacked written description support. The Federal Circuit also affirmed that determination. 

The patent at issue is directed to an optical network assembly with circuits for splitting, amplifying and attenuating optical beams. Claims proposed in the re-examination proceedings were directed to using a planar light guide circuit (PLC). In a first set of claims, the optical assembly equalized the intensities of light in the individual optical paths through the PLC, and in a second set of claims, the optical assembly discretely attenuated the light in the PLC’s individual optical paths. In a third set of claims, the optical network required a “diverting element” within the PLC to cast the optical paths within the PLC into particular circuit patterns.

The parties and the PTAB agreed that under the proper construction, the claimed equalization or claimed discrete attenuation must occur while the light energy is traveling inside the PLC, and the claimed “diverting element” must also be within the PLC. In analyzing the written description support for the diverting element claims, the PTAB determined that the specification lacked written description for any diverting element located within the PLC. For the claims requiring “equalization” or “discrete attenuation,” the PTAB concluded that the disclosure of equalization or attenuation that occurred outside the PLC was sufficient to show possession of the claimed equalization or discrete attenuation inside the PLC. Cisco appealed, and Cirrex cross-appealed. 

The Federal Circuit disagreed with the PTAB’s written description analysis of the “equalization” or “discrete attenuation” claims. First, the Federal Circuit recognized that the parties’ agreed construction accurately captured the broadest reasonable interpretation. In other words, it agreed with the PTAB’s construction that claimed equalization and discrete attenuation must occur while the light energy is traveling inside the PLC. Applying this claim construction to the written description analysis, the Court determined that the claims lacked support, because while the specification disclosed equalization and discrete attenuation that occurred outside the PLC, there was no disclosure of how these features could be implemented inside the PLC. As to the “diverting element” claims, the Court affirmed the PTAB’s determination that these claims did not satisfy the written description requirement because the specification failed to disclose any diverting element located within the PLC. Accordingly, the Federal Circuit found all of the claims proposed in the inter partes re-examination to be unpatentable because they lacked written description support in the specification.