When is a patent infringement defendant entitled to summary judgment of non-infringement under the doctrine of equivalents? That question was addressed in CSB-Systems International, Inc. v. SAP America, Inc., No. 10-2156 (E.D. Pa. April 16, 2012), where the court granted summary judgment of no literal infringement, but denied the defendant summary judgment of non-infringement under the doctrine of equivalents (a.k.a., the “DOE”).
The independent claim of the patent-in-suit, U.S. 5,631,953, recited “[a] circuit arrangement for integration of EDP systems in utilization of telephone systems connected to a public ISDN or Euro ISDN telephone network.” In its claim construction order,
the Court construed the claim term "[t]elephone extensions which are directly connectable to a telephone network selected from the group consisting of a public ISDN telephone network and Euro ISDN telephone network" to mean "telephones and/or other devices such as fax devices of the type that can be connected to either the public ISDN or Euro ISDN telephone network."
The plaintiff's expert, testifying at deposition, “effectively admitted the essential fact that VoIP phones cannot be 'directly connected' to an ISDN telephone network.” The court was thus “precluded from finding literal infringement.” The court also rejected the plaintiff's argument (characterized by the court as "akin" to a motion under Federal Rule of Civil Procedure 56(d) to defer a summary judgment ruling until further facts could be obtained) that it should be allowed to subpoena the defendant's customers to see what kind of interfaces were used.
The court then began its DOE analysis by quoting some familiar boilerplate explaining that a claim that may be infringed under the DOE even if not literally, and that the test for infringement under the DOE was whether there was only an “insubstantial difference” between the accused device and the claim limitation at issue. The court further acknowledged that
"[a]lthough simple to articulate, the doctrine of equivalents is conceptually difficult to apply," and thus requires "particularized testimony" and "linking argument" as to "why the function, way and result of each element in the accused devise [sic] is substantially the same as the elements of the claimed invention." [Citation omitted.] The plaintiff must "articulate the comparison" between the claimed elements and the elements of the accused [device] and present "substantial evidence" comparing the claimed elements and the accused device in each of the three aspects of equivalency, i.e. function, way, and result. [Citations omitted.]
In this case, the defendant first argued “that application of the doctrine of equivalents . . . would violate the 'all elements' rule of the doctrine by removing the limitation of 'directly connectable' to claim.” However, according to the court, the "[p]laintiff's precise contention"was “that there is no substantial difference between a public ISDN or Euro ISDN network and a VoIP network.” (Emphasis in original.) Therefore, the DOE could apply if the plaintiff established the substantial equivalence of these two networks because this “theory . . . maintains the integrity of the 'directly connectable' limitation.”
The defendant further argued that infringement under the DOE could not be proven because the plaintiff had no proof that the defendant or its customers “actually use[d] VoIP networks.” However, the court found no claim language requiring “that the telephone devices actually be connected to the public ISDN or Euro ISDN telephone network -- only that they have the capability to be directly connected to such networks.” The patent claim recited “directly connectable” and not “directly connected.”
Having determined that the defendant was not entitled to summary judgment of non-infringement under the DOE, the court further concluded that genuine issues of material fact precluded summary judgment in the plaintiff's favor. The plaintiff's expert had admitted that VoIP and ISDN networks were different and worked on different protocols. This admission left open the question of whether the networks were substantially different and failed to “satisfy the function-way-means test.”