A question of infringement turned on the meaning of “gateway” in the phrase “intelligent gateway” in a patent claim. The Federal Circuit agreed that a district court was entitled to consult technical dictionaries and use commonly understood meanings of the word to construe the claim. Accordingly, the court affirmed the district court's claim construction, and thus affirmed a summary judgment of non-infringement stipulated to based on the claim construction. Starhome GmbH v. AT&T Mobility, LLC, No. 2012-1694 (Fed. Cir. Feb 24, 2014). The opinion was authored by Judge Schall, joined by Judges Reyna and Moore.
The asserted patent claims of U.S. Patent No. 6,920,487 recited a "system" that included an “intelligent gateway,” and, simply, “an intelligent gateway.” The patent owner argued that “intelligent gateway” meant “a network element that uses knowledge implemented in databases or the like and application logic to perform its operations.” According to the patent owner, the specification simply required the gateway to use a local database, and not to access other networks. The patent owner further contended that the specification disclosed embodiments with “a single intelligent gateway associated with a single mobile network.” The patent owner also argued that claim differentiation supported its construction, because two unasserted claims did recite a connection to an external network.
The defendants countered by arguing “that the patentee used the specific term 'gateway' rather than a generic network element, and that the common usage of that term should control.” The defendants therefore argued, and the district court agreed, that “intelligent gateway” should be construed as “a network element that transfers information to and from a mobile network and another network external to the mobile network.”
In support of their argument, the defendants “point[ed] to three dictionaries showing that 'gateway' refers to a point of interconnection between networks at which information transfer occurs.” The defendants also based arguments on the ’487 patent specification, including an argument that all disclosed embodiments required “the intelligent gateway to directly connect different networks.” The supposed embodiments pointed to by the patent owner simply omitted components not essential to that figure. Further, the defendants argued that claim differentiation did not apply, because all of the dependent claims “recited access to a specific type network.”
The court agreed with the defendants' arguments. It was appropriate to consult technical dictionaries as long as the dictionary definition didn't contradict the patent. Here, the term “gateway” was well-understood in the art. All three relied-upon technical dictionaries evidenced that “one of ordinary skill in the art would have understood a 'gateway' to be a connection between different networks.” Further, modifying “gateway” with “intelligent” did not deviate “from the ordinary meaning of 'gateway.'”
The court also agreed that the ’487 patent's Figure 2 was not a separate embodiment omitting an external network. Rather, it was a call-flow diagram in which a packet-switched network was omitted because it was “not needed to explain the call flow,” as would have been understood by one of ordinary skill. Likewise, claim differentiation did not apply because the unasserted, supposedly differentiated, claims were simply different in scope, “and the district court's construction neither imports limitations from one claim to another nor renders any claims redundant.”
The defendants had also pointed to a related European patent application file history. Noting that sometimes foreign file histories could be relevant, even if they are not to be indiscriminately relied upon, the court considered the file history here. Because the patent owner had argued in the foreign application that the intelligent gateway was defined in terms of accessing one network from another, the court regarded the foreign file history as further support for the defendants' position.
The parties had stipulated that “the accused systems do not directly transfer information to and from a network external to the mobile network,” and agreed that the accused systems had no connections to any external network. Because such a connection was required by the term “intelligent gateway” there could be no infringement, either literally or under the doctrine of equivalents. Therefore, the district court's judgment of noninfringement was affirmed.