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Definitions in Patent Incorporated by Reference Don’t Invalidate Patent

Claim limitations
Don’t apply to all patent
In same family

The Federal Circuit has ruled that the definition of a claim term in a patent incorporated by reference into the patent at issue doesn’t limit the claims in the patent at issue.

In Finjan LLC v. ESET, LLC, Finjan sued Eset claiming that Eset infringed several Finjan patents.

As the court described,

The asserted patents, which are all expired, are part of a family of patents directed to systems and methods for detecting computer viruses in a “Downloadable” through a security profile.

Finjan claimed priority for each of the asserted patents back to a provisional application filed in 1996.

In 2017, a district court held a hearing focusing on the meaning of the term “downloadable,” which appears in all the asserted patents. One of the asserted patents defines downloadable as

an executable application program which is automatically downloaded from a source computer and run on the destination computer. Examples of Downloadables include applets designed for use in the Java™ distributing environment . . . .

Two of the asserted patents define a downloadable as

a small executable or interpretable application program which is downloaded from a source computer and run on a destination computer.

[Emphasis added by the court.]

The district court adopted the latter definition above, to include the word “small.”

The case went to trial in March of 2020, then was vacated due to California’s COVID-19 stay-at-home order.

A year later, the court granted ESET’s motion for summary judgment, finding the asserted patents indefinite based on the word “small” as used in the court’s construction of “downloadable.”

On appeal, the Federal Circuit held that the district court erred by adding the term “small” to the definition of “downloadable,” saying

The district court erred because it viewed the differing definitions throughout the patent family as competing and determined that the asserted patents should be limited to the most restricted definition of the term. We disagree. Here, it is not necessary to limit the asserted patents because the two definitions are not competing. 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.

The court noted that “definitions in any incorporated patents or references are a part of the host patent.” However, “incorporation by reference does not convert the invention of the incorporated patent into the invention of the host patent.”

Rather, the disclosure of the host patent provides context to determine what impact, if any, a patent incorporated by reference will have on construction of the host patent claims….. “The disclosures of related patents may inform the construction of claim terms common across patents, but it is erroneous to assume that the scope of the invention is the same such that disclaimers of scope necessarily apply across patents. . .”


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.

The patent that defines a Downloadable as “small,” said the court,

represents a subset of the patent family claiming an invention capable of downloading only small executable or interpretable application programs. That is because the disclosure in the ’520 Patent focuses on applets as small executable or interpretable application programs.


The definition of “Downloadable” that does not include a size requirement refers to executable or interpretable application programs of all sizes, including, but not limited to, “small” executable or interpretable application programs.

Just like the haiku above, we like to keep our posts short and sweet. Hopefully, you found this bite-sized information helpful. If you would like more information, please do not hesitate to contact us here.

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