Kara Tech. Inc. v. Stamps.com Inc., (Fed. Cir. Sept. 24, 2009)
In this case, the district court (Central District of California) entered a final judgment of noninfringement following a jury trial. The Federal Circuit, in an opinion by Judge Moore, held that the district court erred in construing the patent claims and therefore vacated the finding of noninfringement and remanded back to the district court for further proceedings.
The patents at issue are directed toward apparatuses and methods of creating and verifying the authenticity of documents such as postage. As explained by the Federal Circuit, "[t]he patents concern a technology that allows a customer to print a secured document (such as a stamp or an an airline ticket) at home using preprinted label sheets." At issue during claim construction were three claim phrases concerning creation and validation of security indicia. More specifically, as the Federal Circuit noted, the issue turned on "whether the security indicia must be created and validated under control of a key contained in the preestablished data." The district court had construed the term "security indicia" by stating that it must "be created under control of a key" and stated that the information contained in the preestablished data must be a "key."
The Federal Circuit found that the asserted claims did not require the use of a key for three reasons. First, the asserted claims did not explicitly mention the existence of a "key" in the preestablished data, only the existence of "information." Second, all of the nonasserted independent claims require an "encryption key" or "key data." Under the doctrine of claim differentiation, there is a presumption that the asserted claims, which do not contain such a limitation, do not require the existence of a "key." Third, while the "specification repeatedly discusses a key embedded in the preestablished data ... [t]his is not enough  to limit the patentee's clear, broader claims ... [as the patentee] did not act as his own lexicographer or disavow claim scope." While there were technical experts on both sides that took opposing views on this issue, the Federal Circuit stated that "[i]t is not uncommon in patent cases to have such dueling experts ... [and] [w]hile helpful, extrinsic sources like expert testimony cannot overcome more persuasive intrinsic evidence."
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