by Dennis Crouch
The Federal Circuit has affirmed summary judgment of non-infringement in DoggyPhone LLC v. Tomofun LLC, agreeing to narrowly construe the claim as requiring direct rather than indirect causation. The case involves U.S. Patent 9,723,813, which covers an “Internet Canine Communication System” that allows pet owners to remotely interact with and deliver treats to their dogs. DoggyPhone accused Tomofun’s popular Furbo device of infringement, but both the district court and Federal Circuit found the accused product operates differently than what was claimed. Writing for the unanimous panel, Judge Hughes focused particularly on one key limitation requiring that the system “begins transmission to the remote client device of at least one of the audio or video of the pet in response to input from the pet.”
At the heart of the dispute is a basic infringement question – whether Furbo’s notification system satisfied the “begins transmission” limitation. When a dog barks, the Furbo sends a text notification to the owner’s phone, but critically, no audio or video transmission begins until the owner actively clicks on that notification. The Federal Circuit agreed with the district court that this setup does not meet the claim limitation because “transmission begins not in response to the pet’s activity, but in response to the user’s decision to click on the notification—making transmission responsive to the user’s input, not the pet’s.”
DoggyPhone argued that the pet’s barking was still causally connected to the ultimate transmission, since without the initial bark triggering the notification, no transmission would ever occur. The Federal Circuit rejected this “but-for causation” theory, explaining that “it is not sufficient that the pet’s activity sets off a causal chain that may or may not result in transmission of live video or audio.” The claim language requires that the pet’s activity “begins transmission,” not merely that it “begins a process of transmission.”
The court’s analysis turned heavily on the precise claim language chosen by the patentee. Rather than claiming a broader system where pet activity could indirectly lead to transmission through intervening steps, the patent specifically required that transmission “begins…in response to input from the pet.” The Federal Circuit found this language to be more limited than DoggyPhone’s proposed interpretation that would encompass any causal relationship between pet input and eventual transmission. “[I]t is not sufficient that the pet’s activity sets off a causal chain that may or may not result in transmission of live video or audio. The claim language requires that the pet’s activity begins transmission, not that the pet’s activity simply causes transmission.”
Although not reflected in the opinion, the oral arguments also highlighted arguments about waiver or “a new bark on appeal”: During district court proceedings, DoggyPhone had advocated for (and received) a “plain and ordinary meaning” construction of the key phrase “begins transmission…in response to input from the pet.” Only later did DoggyPhone argue this inherently meant “triggered or causally connected,” pointing to statements from IPR proceedings where such language was used. Judge Hughes pressed DoggyPhone’s counsel David Lowe on this point:
Judge Hughes: Did you argue that this claim term needed to be construed and that the proper construction included whatever we’ve been talking about with the causally linked? You didn’t do that, did you?
David Lowe: I don’t believe we did, Your Honor.
In this discussion, Lowe went on to argue that DoggyPhone believed the plain and ordinary meaning included ‘triggered or causally connected’ based on the district court’s discussion, but Judge Hughes pointed out this wasn’t actually part of the formal construction. Tomofun’s attorney Jonathan Giroux argued that, “DoggyPhone can’t now say that plain and ordinary meaning is not sufficient and we have to reverse the trial court when it asks for that claim construction.”
Unlike traditional statutory interpretation or precedential analysis where courts must determine the correct legal meaning regardless of party positions, claim construction occupies a different space as a legal issue that can be shaped and bounded by party agreements. While the Federal Circuit has consistently held that claim construction is a question of law reviewed de novo (except for certain non-legislative, adjudicative factual conclusions), the court’s interpretative role is fundamentally constrained by how parties frame and present claim construction disputes during litigation. A party’s strategic decision to advocate for “plain and ordinary meaning” or failure to raise specific construction arguments can effectively waive alternative interpretations, even if those interpretations might have been viable if timely raised. The practical impact is that claim construction, though technically a legal issue, operates as a case-focused legal determination where party choices, concessions, and agreements play a central role in defining the scope of potential constructions available to the court. This stands in marked contrast to pure statutory interpretation, where courts remain duty-bound to determine the correct reading of the law even when parties agree to an incorrect interpretation or fail to identify the proper analysis.
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The Federal Circuit’s decision comes after Tomofun previously failed to invalidate the ‘813 patent through inter partes review (IPR). In May 2021, the PTAB denied institution of IPR2021-00260, finding that Tomofun failed to show a reasonable likelihood of prevailing on any challenged claim. The PTAB denied institution primarily because none of the prior art references disclosed a system that “plays via the audio device an audio signal that notifies the pet of availability of a treat” in response to receiving a treat delivery command. While the various references disclosed both treat delivery commands and playing audio signals to pets, none established that the audio signal was played as a direct response to receiving the treat delivery command. One reference disclosed playing music and owner voices through speakers but didn’t specify these were triggered by treat commands.
The importance of the sequence is highlighted by the PTAB’s emphasis on causation versus mere co-occurrence. The claim specifically requires that the audio signal be played “in response to” the treat delivery command – establishing a clear cause-and-effect relationship where the treat command triggers the audio notification. The PTAB found this sequence meaningful enough that even when prior art showed systems capable of both actions, without explicit disclosure of this particular triggering relationship, the references failed to meet the claim limitation.
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This case highlights the strategic value of maintaining continuation applications. While hindsight is 20/20, the patentee might have benefited from claims specifically covering both direct and indirect causation scenarios. Notably, the PTAB’s IPR decision suggested that the patentability of the ‘813 patent didn’t turn on the direct causation requirement that proved fatal to infringement. Had DoggyPhone maintained continuation rights, it could have pursued claims better suited to cover competitor implementations like Furbo’s notification-then-transmission approach.
I should note that the defendant had alternative non-infringement arguments, including one focusing on means-plus-function language.
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The opinion was authored by Judge Hughes, and joined by Judges Taranto and Cunningham.
Plaintiff-Appellant DoggyPhone LLC was represented by David Lowe of Lowe Graham Jones PLLC (Seattle), who argued the case.
Defendant-Appellee Tomofun LLC was represented by Jonathan Giroux of Greenberg Traurig P.A. (Chicago), who argued the case. Additional counsel for Tomofun included James J. Lukas, Jr. (Chicago) and Erik Bokar (Orlando) of Greenberg Traurig.