A court may find that an accused device infringes an asserted patent even though it does not literally meet an explicit limitation if there is an insubstantial change in the way the [accused] device meets the limitation due to advances in technology.

The asserted patents generally relate to technology for reducing acoustic feedback in a programmable digital hearing aid. The alleged infringer sought an appeal [on] from the district court’s denial of its motions for JMOL of no infringement under the doctrine of equivalents. The Federal Circuit affirmed the district court’s ruling that the alleged infringer infringed one of the two patents.

The Federal Circuit “reviews the grant or denial of a motion for JMOL or for a new trial under the law of the regional circuit.” Here, the Federal Circuit reviewed the district court’s decision under the law of the Third Circuit. Under Third Circuit law, the Federal Circuit conducted a plenary review of the district court’s decisions concerning JMOL and determined if there was insufficient evidence from which a jury could reach its conclusions, viewing the evidence in the light most favorable to the non-movant. The jury found that one of the asserted patents was infringed using a “verdict form requir[ing] only a yes/no response to the question [of] whether [the alleged infringer’s] products infringed each of the asserted claims.” Although the alleged infringer argued that it was not explicit in the verdict form whether its accused products met the claim limitations, “there was substantial evidence from which to conclude that . . . each of the disputed limitations” were met. Specifically, the claims required an external host to calculate and program filter coefficients. In contrast, the accused devices did not have an external host, rather the calculation and programming were performed inside the hearing aid. Hence, the external host limitation was not literally met, nor did the jury’s verdict detail how that limitation was met.

Nonetheless, the Federal Circuit held that “[w]hile the improvement in technology allows the defendants’ products to constantly recalculate filter coefficients using electronics located on the hearing aid, the accused devices nonetheless perform the same function in substantially the same way, with substantially the same result claimed by the [asserted patent].” Moreover, in its attempt to invalidate the asserted patents, the alleged infringer failed to show that the range of equivalence included the prior art. Indeed, case law states that “the patentee bears the ultimate burden of persuasion to show that its claims do not cover the prior art,” but at the same time, the alleged infringer must still present prior art showing that the “asserted range of equivalence would encompass the prior art.” Here, the alleged infringer did not present prior art supporting its position.

A copy of the opinion can be found here.