In Google LLC v Sonos Inc, 2024 FCA 44, the Federal Court of Appeal dismissed Google’s appeal of a Federal Court decision that found that Sonos did not infringe claim 7 of Google’s Canadian Patent No. 2,545,150. Google disagreed with the Federal Court’s interpretation of the terms “echo cancellation” and “an order” in claim 7.
Claim 7 of the Google patent recites:
7. An electronic device, comprising:
an audio input configured to receive a received signal;
an audio output configured to output an output signal;
a transceiver configured to transmit a transmitted signal; and
an adaptive echo and noise control system coupled to the audio input,
the audio output, and the transceiver,
the adaptive echo and noise control system including
an echo canceller; and
a noise suppressor,
wherein the adaptive echo and noise control system is configured to
adaptively determine an order of echo cancellation and noise suppression based on an amount of noise in the received signal to generate a desired signal,
and wherein the adaptive echo and noise control system is further configured to send the desired signal to the transceiver.
On the basis of expert evidence, the Federal Court had found that “echo cancellation” was a distinct process from noise suppression and rejected Google’s argument that echo cancellation was not limited to mechanisms using a reference signal and a cancellation point, but included other mechanisms that treated echo as noise.
The Federal Court also weighed conflicting expert evidence to determine that there would be no “order of echo cancellation and noise suppression” where only either echo cancellation or noise suppression was performed. Google argued that the term “an order” could encompass an order in which either process was available but not performed.
The Federal Court of Appeal began with commenting on the applicable standard of review. In accordance with the Supreme Court of Canada’s decision in Housen v Nikolaisen, 2002 SCC 33, the Federal Court of Appeal noted that questions of law are reviewed for correctness, whereas questions of mixed fact and law are reviewed for palpable and overriding error.
The Federal Court of Appeal then held that interpretation of patent claims is in theory a question of law and therefore subject to the correctness standard. However, because claims are interpreted from the perspective of a person skilled in the art and because courts often consider expert evidence to determine how a person skilled in the art would interpret the claims, claims interpretation is in practice often a question of mixed fact and law. Therefore, claims interpretation is to be reviewed on the palpable and overriding error standard when the interpretation turns on the weight given to expert evidence.
The Federal Court of Appeal reviewed the Federal Court’s interpretation of claim 7 for palpable and overriding error and found none. Accordingly, the appeal was dismissed.
A copy of the decision is available here.