The US Court of Appeals for the Federal Circuit rejected an insufficiently developed claim construction challenge and found noninfringement where the patentee argued that a key feature shared by the accused device and the prior art distinguished the prior art from the claimed invention. CommScope Technologies LLC v. Dali Wireless Inc., Case Nos. 20-1817; -1818 (Fed. Cir. Aug. 24, 2021) (Stoll, J.)

CommScope Technologies and Dali Wireless are both in the wireless telecommunications industry. After CommScope sued Dali for infringement of five of its patents, Dali counterclaimed for infringement of two of its own patents. One of Dali’s patents relates to a method of predistorting a signal to account for distortion that occurs when the signal is amplified. The patent describes a training mode in which a feedback loop operates to update lookup tables and an operating mode in which a certain controller is turned off and the lookup table is no longer updated. In particular, the claim recites “switching a controller off to disconnect signal representative of the output of the power amplifier,” which the district court construed to mean “switching a controller to a nonoperating state to disconnect signal representative of the output of the power amplifier.” The accused product has two power amplifiers, and the controller switch continuously chooses between feedback signals for calculating predistortion values. Similarly, one asserted prior art reference discloses a system including multiple power amplifiers and a switch that continuously selects one of the feedback signals. At trial, the jury found the patent both valid and infringed, and the district court denied judgment as a matter of law (JMOL) of invalidity and no infringement.

On appeal, Dali included a footnote challenging the district court’s claim construction. The Federal Circuit held this challenge ineffective for three reasons, writing:

First, an argument that is only made in a footnote of an appellant’s brief is forfeited. Second, even if the argument were in the body of the brief, it is insufficiently developed. Finally, and most importantly, it is irreconcilable with Dali’s statements in other portions of its brief: (1) asserting that the district court’s construction is “unchallenged” and (2) applying the construction in the context of invalidity.

The Federal Circuit also criticized Dali for taking inconsistent positions with respect to application of its claims to the accused product and the prior art “given [the accused device] has a switch that operates identically [to the prior art.” “[t]his case falls squarely within the principle that a ‘patent may not, like a nose of wax, be twisted one way to avoid anticipation and another to find infringement.’” The Court held that no substantial evidence supported the infringement verdict because there was no evidence that the controller in the accused product put itself in the claimed “nonoperating state.” Accordingly, it reversed the denial of JMOL of noninfringement (while affirming the balance of the judgment below).