In Finjan LLC v. ESET, LLC,1 the Federal Circuit held that a definition provided in any incorporated-by-reference document is a part of the host patent. However, the use of a restrictive definition of a claim term in an earlier parent application does not reinstate that restrictive definition in a later continuing application that purposely deletes the term, even if the earlier parent application is incorporated by reference.
Finjan, Inc., sued ESET, LLC, contending that ESET infringed U.S. Patent Nos. 6,154,844 (’844 Patent), 6,804,780 (’780 Patent), 8,079,086 (’086 Patent) and 9,189,621 (’621 Patent) (collectively, asserted patents or patents-at-issue). The asserted patents were part of a family of patents describing systems and methods for finding computer viruses in a “downloadable” using a security profile. Finjan claimed priority back to provisional application No. 60/030,639 (’639 application), filed on November 8, 1996.
The term “downloadable” was recited in the claims of all the asserted patents. The ’639 application defined a downloadable as an executable application program that is automatically downloaded from a source computer and executed on the destination computer. Non-asserted U.S. Patent Nos. 6,167,520 (’520 Patent) and 6,480,962 (’962 Patent) defined a downloadable as an applet and as a small executable or interpretable application program that is downloaded from a source computer and executed on a destination computer. The district court interpreted the term “downloadable” to mean “a small executable or interpretable application program which is downloaded from a source computer and run on a destination computer.”2 The court supported its interpretation using the incorporation by reference of the ’520 Patent.
On appeal, the Federal Circuit reversed. Finjan asserted on appeal that the district court incorrectly interpreted the term “downloadable” to be limited to a “small” executable application program. Specifically, Finjan contended that the district court mistakenly included the word “small” in the definition of “downloadable.” The Federal Circuit agreed. The court noted that claims must be interpreted in view of the specification. “That includes any patents incorporated by reference,” the court said.3 Incorporation by reference of a patent enables the entire contents of that patent’s disclosure to be a part of the host patent. “Accordingly, definitions in any incorporated patents or references are a part of the host patent,” the Federal Circuit said.4 The court also explained that the technical description of the host patent offers the background to decide whether a patent incorporated by reference will influence the interpretation of the host patent claims.
The court observed that the district court mistakenly considered the different definitions for the term “downloadable” in the patent family as inconsistent and determined that the term in the patents being litigated should be confined to the most limited definition of the term. The Federal Circuit disagreed because it was not essential to limit the definition of the term in the patents being litigated because the different definitions could be reconciled. The court reasoned, “The use of a restrictive term in an earlier application does not reinstate that term in a later patent that purposely deletes the term, even if the earlier patent is incorporated by reference.”5
Here, the ’520 Patent, which defined a downloadable as “small,” was only a subset of the patent family that characterized the invention as downloading only small executable or interpretable application programs. The court reasoned that the disclosure in the ’520 Patent concentrated the technical description on applets as small executable application programs.
However, the court noted that the definition of “downloadable” that did not include a size requirement referred to executable application programs of all sizes, including small executable application programs. The court reasoned that since these two definitions could be reconciled within the patent family, the ’520 Patent’s definition of “downloadable” did not have to be applied to the asserted patents.
For example, the ’844 Patent and the ’780 Patent described a downloadable as “an executable application program, which is downloaded from a source computer and run on the destination computer.”6 This definition was not restricted to small executable application programs. The ’844 Patent and the ’780 Patent defined “downloadable” to encompass a broader task not restricted to downloading only small executable application programs, and the examples in the ’844 Patent and the ’780 Patent offered additional support. Therefore, the court concluded that in the ’844 Patent and the ’780 Patent, “downloadable” should not be interpreted to contain the term “small.” The court explained:
In sum, the term “Downloadable” as used in the ’844, ’780, ’086, ’621, and ‘755 Patents means “an executable or interpretable application program, which is downloaded from a source computer and run on the destination computer.”7
The court therefore reversed the district court’s claim interpretation and held that the term “downloadable” should be construed as “an executable or interpretable application program, which is downloaded from a source computer and run on a destination computer.”8
Takeaways
Claim terms/words are generally given their ordinary and customary meaning in view of the specification. The ordinary and customary meaning is determined from the vantage point of what one of ordinary skill in the art at the time of the invention would have understood the claim term to mean. The specification is the single best guide to the meaning of a claim term that can be used to define it.
Words in the patent specification and claims matter: The patent specification and claims define the legal scope of protection for an invention. That is, an incorrect description, whether in the specification or claims, can result in an unnecessarily narrow or limited invention. This decision cautions that when prosecuting a patent portfolio of related applications incorporated by reference in a chain of priority, applicants/owners and their representatives must accurately and clearly describe and claim the invention.
The practical effect of this decision is to warn patent owners that the specification and claims will be scrutinized later during litigation. Thus, the specification and claims need to be strategically articulated based on a well-informed understanding of the meaning of terminology in the prior art. Alternatively, the specification and claims can provide an explicit definition. However, care should be taken to make sure the provided definition does not conflict with related applications that may be incorporated by reference into the specification.
Irah Donner is a partner in Manatt’s intellectual property practice and is the author of Patent Prosecution: Law, Practice, and Procedure, Eleventh Edition, and Constructing and Deconstructing Patents, Second Edition, both published by Bloomberg Law.
1 Finjan LLC v. ESET, LLC, 51 F.4th 1377, 2022 USPQ2d 946, 2022 WL 16557653 (Fed. Cir. 2022).
2 Id., 51 F.4th at 1382 (emphasis by court).
3 Id., 51 F.4th at 1382.
4 Id., 51 F.4th at 1382.
5 Id., 51 F.4th at 1383.
6 Id., 51 F.4th at 1383 (quoting ’844 Patent col. 1 ll. 45–47; ’780 Patent col. 1 ll. 51–53).
7 Id., 51 F.4th at 1383.
8 Id., 51 F.4th at 1384.