Only the First, Ltd. v. Seiko Epson Corp., No. 07 C 1333, Slip Op. (N.D. Ill. Sep. 29, 2010) (Dow, J.).

Judge Dow, having previously construed the claim of plaintiff’s patent to a color printing system, granted defendant Seiko Epson Corp. ("SEC") summary judgment of noninfringement. Each claim required, among other colors, green-yellow ink. Plaintiff admitted that SEC’s yellow did not fall within the Court’s green-yellow construction.

Instead, Plaintiff argued that SEC’s yellow was equivalent to the claimed green-yellow based upon the doctrine of equivalents because although SEC’s yellow was a red-green the human eye perceived it as a yellow. But plaintiff’s evidence only proved that SEC’s yellow appeared yellow. Plaintiff had no evidence that SEC’s yellow appeared green-yellow, the color of the relevant claim limitation. Regardless of the correctness of plaintiff’s argument, therefore, plaintiff had not met its burden. And plaintiff could not use the doctrine of equivalents to expand green-yellow to all yellows.