The US Court of Appeals for the Federal Circuit ruled that a claim interpretation that flows naturally from the parties’ stipulated claim construction is binding on the parties even if the interpretation reads preferred embodiments out of the claims. Finjan LLC v. SonicWall, Inc., Case No. 22-1048 (Fed. Cir. Oct. 13, 2023) (Reyna, Cunningham, JJ.) (Bryson, J., dissenting).

In 2017, Finjan sued SonicWall for infringing several of Finjan’s patents related to cybersecurity technology systems that identify malicious material in downloadable content and programming code. The asserted patents included claims directed to ways to protect network-connectable devices from undesirable downloadable operations. During claim construction, the parties stipulated that a “downloadable” should be construed as “an executable application program, which is downloaded from a source computer and run on the destination computer.”

SonicWall moved for summary judgment, arguing that it did not infringe the patents because the accused devices received and inspected supposed “downloadables” as unextracted packets, which do not constitute executable files under the stipulated claim construction. The district court granted partial summary judgment in favor of SonicWall, finding that Finjan failed to offer evidence that “the accused […] products ‘ever possess a reassembled file or executable application.’” Finjan appealed.

Finjan argued that the district court’s ruling was incorrect because it impermissibly grafted additional requirements onto the stipulated claim construction, and that the district court’s interpretation was inconsistent with claim language found in other parts of the asserted patents. The Federal Circuit rejected these arguments, noting that the district court’s infringement ruling followed directly from the parties’ stipulated definition of the term “downloadables.” Under the stipulated claim construction and in accordance with Finjan’s own expert’s interpretation of the meaning of “executable,” a device “that merely receives and forwards packets without reassembling their contents does not receive a downloadable . . . because that device does not receive an executable application program.” The Court emphasized that Finjan could not challenge its earlier claim construction stipulation. Further, the Court noted that the stipulated definition of “downloadables” was derived verbatim from the specifications of two of the asserted patents.

Judge Bryson dissented for two reasons. First, he noted that the district court’s interpretation of the claims would read preferred embodiments out of the patent and effectively eviscerate from the patent’s scope any device that screens content from the internet. Second, Judge Bryson found that elsewhere in the asserted patents’ specifications it was clear that the meaning of “downloadables” used by the district court was incorrect. Contrary to the majority, Judge Bryson did not find the stipulated claim construction dispositive because Finjan merely challenged the meaning of the word “executable” within the stipulated claim construction, rather than the contents of the stipulation itself.

Practice Note: This decision offers a few helpful lessons for practitioners. First, it is important to write claims in language that is both expansive enough to encompass all intended embodiments but precise enough to survive invalidity challenges. By carefully selecting specific but broad language, and writing claims more accurately, patentees may avoid semantic noninfringement arguments. Second, practitioners should be punctilious in making stipulations during claim construction as they will likely not have the opportunity to challenge any stipulation later.

This article was authored by Ian Howard.