The U.S. Court of Appeals for the Federal Circuit reversed a finding of literal infringement, finding an erroneous claim construction and that there could not be infringement under the doctrine of equivalents because of prosecution history estoppel. PODS, Inc. v. Porta Stor, Inc., Case No. 06-1504 (Fed Cir., Apr. 27, 2007) (Dyk, J.)

PODS initially brought suit against Porta Stor alleging infringement of a patent relating to an apparatus and method for lifting and lowering a storage container in and out of a truck. The district court granted PODS a judgment (of infringement) as a matter of law (JMOL) at the close of evidence on the patent claims, on the grounds that one claim of the patent was literally infringed and that other claims were infringed under the doctrine of equivalents.

On appeal, Porta Stor argued that the district court erred in not construing the phrase “carrier frame” in one claim to have the same meaning as it did in other claims. The Federal Circuit, applying a “presumption that the same terms appearing in different portions of the claims should be given the same meaning unless it is clear from the specification and prosecution history that the terms have different meanings at different portions of the claims,” held that the term “carrier frame” should be defined as having four sides because of the parties’ earlier agreement that at least one claim containing that term required a four-sided carrier frame and that the only embodiments disclosed in the specification were four-sided. Based on this construction, the Court concluded that the accused device, which embodied a U-shaped or open-ended carrier frame, did not literally infringe.

The Court also denied resort to the doctrine of equivalents because of the patentee’s arguments, urged against a rejection of one claim, that it required a rectangular frame. The Federal Circuit maintained that prosecution history estoppel applied to all claims for a term which an argument was made to overcome prior art and that “PODS’s arguments during prosecution bar it from asserting that Porta Stor’s device infringed [a] claim … under the doctrine of equivalents.” The Court thus held that a competitor would reasonably believe that PODS had surrendered any claim to a frame that was not rectangular or four-sided in shape, including Porta Stor’s three-sided, U-shaped device. As to later added claims, the Court noted that “once an argument is made regarding a claim term so as to create an estoppel, the estoppel will apply to that term in other claims.”