Energy Transportation Group, Inc. v. William Demant Holding A/S

Prosecution history estoppel bars the assertion of the doctrine of equivalents when the presumption that a key claim phrase was narrowed to secure the patent in question is not overcome.

Opinion (Rader): Co-defendants William Demant Holding A/S, WDH, Inc. (“Demant”) and Widex A/S (“Widex”) appealed the jury finding that they infringed the Energy Transportation Group, Inc. (“ETG”) ‘850 patent, by challenging the scope of ETG’s possession of adaptive programmable features in the ‘850 that reduced acoustic feedback in hearing aids. The Court affirmed the jury’s finding because the ‘850 abstract conveyed the invention as an adaptive hearing aid, and because the testimony, “[no]body but a red faced liar could…say the ‘850 [patent] does not contemplate adaptive filtering” by the defendant’s expert provided substantial evidence for the jury’s finding. Demant and Widex also challenged the damages award, but the Court found no error in the admittance of trial evidence supporting ETG’s damages claim, and no evidence showing the jury’s award was outrageous. Widex appealed the denial of its motion for JMOL of no willful infringement, but the Court declined to reach the issue because ETG’s motions for enhanced damages and attorney fees was denied by the trial court and ETG did not appeal. Finally, ETG cross-appealed the grant of JMOL of non-infringement of its ‘749 patent by asserting the doctrine of equivalents for key phrases ETG changed to secure the ‘749. The Court affirmed that prosecution history estoppel bars use of the doctrine of equivalents, because the prosecution history showed no reasons for the change, and because the difference in phrases was clearly foreseeable. Judgment was AFFIRMED.