The US Court of Appeals for the Federal Circuit reversed and vacated a decision by the Patent Trial & Appeal Board, explaining that the Board failed to consider common textual modifier language when applying the plain meaning to a disputed claim term. Netflix, Inc. v. DivX, LLC, Case No. 24-1541 (Fed. Cir. Feb. 13, 2026) (Moore, C.J.; Dyk, Taranto, JJ.)

DivX sued Netflix for infringing its patent directed to systems and methods for streaming partly encrypted media content. The patent uses encryption/decryption, a Digital Rights Management (DRM) technique, to protect streams of media content from unauthorized access or copying. This technique requires that cryptographic information be relayed to the playback device for users to watch streamed media content. The patent explains that encrypting parts of streamed media decreases the resources needed for encryption/decryption and provides the playback device with information on the portions that are encrypted and “common” decryption information.

Netflix petitioned for inter partes review (IPR) of all claims on the basis of obviousness. The Board rejected DivX’s proposed construction of limitation [l] of the representative claim: “locating encryption information that identifies encrypted portions of frames of video within the requested portions of the selected stream of protected video.” DivX’s argued that the “encryption information” must be located “within the requested portions of the selected stream of protected video.” The Board deemed DivX’s proposed claim construction as “too restrictive,” concluding that the claim suggested that the encryption information just needed to identify encrypted portions of frames that themselves were “within the requested portions of the selected stream of protected video.”

In its final written decision, the Board agreed with Netflix that a person of skill in the art would have been motivated to combine the asserted prior art but held that the artisan would not have reasonably expected success in combining the prior art and that therefore Netflix did not establish obviousness of the challenged claims.

The Federal Circuit vacated the Board’s decision on appeal and remanded the matter. On remand, the Board again concluded that Netflix did not demonstrate obviousness but this time accepted DivX’s originally proposed claim construction. Netflix appealed.

The Federal Circuit found the Board’s construction of limitation [l] was erroneous, agreeing with Netflix that limitation [l] was taught by the asserted prior art combination. Using the plain language doctrine, the Court found that limitation [l] was susceptible to two interpretations: “the modifier ‘within the requested portions of the selected stream of protected video’ could modify either ‘encrypted portions of frames of video’ or ‘encryption information.’” Accordingly, the Court relied on the principle that where commas or other textual signals are not used, it is presumed that the modifier is tied to the nearest available semantically plausible modificand. The Court determined that only the “encrypted portions of frames of video” needed to be “within the requested portions of the selected stream of protected video.” The Federal Circuit also determined that the context of the claim itself, the specification, and the prosecution history supported the construction that [...]

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