In Continental Circuits LLC v. Intel Corp. et al., case number 18-1076, the U.S. Court of Appeals for the Federal Circuit, in a precedential opinion, recently clarified the rules for the incorporation of a limitation from a patent’s specifications into the claims during claim construction.  In the case, Continental sued Intel Corp.; its supplier, Ibiden U.S.A. Corp.; and Ibiden U.S.A. Corp.’s parent company, Ibiden Co. Ltd. (collectively, “Intel”), for patent infringement on four patents in the District of Arizona.

All four patents at issue in the case share a common specification and are directed to a “multilayer electrical device . . .having a tooth structure” and methods for making the same.  According to the patents, multilayer electric devices “suffer from delamination, blistering, and other reliability problems,” especially when “subjected to thermal stress.”  The inventions of the patents purport to solve this problem by “forming a unique surface structure . . . comprised of teeth that are preferably angled or hooked like fangs or canine teeth to enable one layer to mechanically grip a second layer.”  The specification further explains that the increased surface area of the teeth improves the adhesion of the layers to one another.  The patents additionally “theorize[] . . . that the best methods for producing the teeth [are] to use non-homogenous materials and/or techniques . . . such that slowed and/or repeated etching will form teeth instead of a uniform etch.”  The specification then explains that “[o]ne technique for forming the teeth is . . . the swell and etch or desmear process, except that contrary to all known teachings in the prior art . . . a ‘double desmear process’ is utilized.”  It continues by explaining that “the peel strength produced in accordance with the present invention is greater than the peal [sic] strength produced by the desmear process of the prior art, i.e., a single pass desmear process.”  The specification then discloses that “[i]n stark contrast with the etch and swell process of the known prior art . . . a second pass through the process . . . is used” because it “make[s] use of [the] non-homogenaities [sic] in bringing about a formation of the teeth.”

All of the asserted claims include claim limitations regarding the “surface,” “removal,” or “etching” of “a dielectric material” or “epoxy,” and their construction depends on resolving whether they should be limited to a repeated desmear process.  The district court construed the “surface,” “removal,” or “etching” claims of the dielectric material to be “produced by a repeated desmear process.”  The district court concluded that Intel had “met the exacting standard required” to read a limitation into the claims.  Specifically, the district court found that the specification not only “repeatedly distinguishe[d] the process covered by the patent from the prior art and its use of a ‘single desmear process,’” but also characterized “the present invention” as using a repeated desmear process.  Additionally, the district court found that the prosecution history corroborated its construction.

In reviewing the claim construction, the Federal Circuit first noted that claim construction is ultimately a question of law that it reviews de novo.  Any subsidiary factual findings based on extrinsic evidence “must be reviewed for clear error on appeal.”  But “when the district court reviews only evidence intrinsic to the patent (the patent claims and specifications, along with the patent’s prosecution history), the judge’s determination will amount solely to a determination of law,” which the Federal Circuit will review de novo.

The Federal Circuit acknowledged the difficulty in drawing the “fine line between construing the claims in light of the specification and improperly importing a limitation from the specification into the claims.”  To avoid improperly importing limitations into the claims, “it is important to keep in mind that the purposes of the specification are to teach and enable those of skill in the art to make and use the invention and to provide a best mode for doing so.”  In contract, to disavow claim scope (or, in other words, limit the claims via the specification), “the specification must contain ‘expressions of manifest exclusion or restriction, representing a clear disavowal of claim scope.’”

The Federal Circuit then found that the district court erred in limiting the claims to require a repeated desmear process.  Based on its review of the specification, none of the statements relied upon by the district court rises to the level of “a clear and unmistakable disclaimer.”  Thus, absent “clear and unmistakable” language suggesting otherwise, the Federal Circuit concluded that the aforementioned statements do not meet the “exacting” standard required to limit the scope of the claims to a repeated desmear process.

The district court had also found that the prosecution history further supported its claim construction; however, the Federal Circuit disagreed that such a clear disavowal existed in the prosecution history.  Similar to disclaimers in the specification, “[t]o operate as a disclaimer, the statement in the prosecution history must be clear and unambiguous, and constitute a clear disavowal of scope.”  But, according to the Federal Circuit, the cited statements in the prosecution history do not clearly and unmistakably disavow any claim scope.

Next, in order to read a process limitation into a product claim, it must meet one more criterion.  Generally, “[a] novel product that meets the criteria of patentability is not limited to the process by which it was made.”  “However, process steps can be treated as part of a product claim if the patentee has made clear that the process steps are an essential part of the claimed invention.”  Thus, for the same reasons that the statements relied upon by the district court do not show that the patentee clearly and unmistakably disavowed claim scope, they also do not make clear that the repeated desmear process is “an essential part” of the claimed electrical device having a tooth structure.

Finally, in some instances, district courts are authorized “to rely on extrinsic evidence, which ‘consists of all evidence external to the patent and prosecution history, including expert and inventor testimony, dictionaries, and learned treatises.’”  However, “while extrinsic evidence ‘can shed useful light on the relevant art,’” it is “less significant than the intrinsic record in determining the ‘legally operative meaning of disputed claim language.’”  Here, the district court acknowledged that the extrinsic evidence, which consisted of documents authored by the inventors, was “not reliable enough to be dispositive,” but “provide[d] helpful corroboration.”  However, similar to the intrinsic evidence, those statements reflect use of the preferred embodiment but give the public no indication that they have any limiting effect.  Therefore, because the Federal Circuit already determined that the intrinsic evidence does not support reading a repeated desmear process into the claims, the “less reliable” extrinsic evidence, which even the district court acknowledged was “not reliable enough to be dispositive,” does not require otherwise.

Accordingly, the Federal Circuit determined the claim terms should not be limited to requiring a repeated desmear process, and instead, should be given their plain and ordinary meaning.