Midtronics, Inc. v. Aurora Performance Prods. LLC, No. 06 C 3917, 2008 WL 2745941, (N.D. Ill., Jul. 11, 2008) (Shadur, Sen. J.).

Judge Shadur construed the disputed terms of plaintiffs’ electronic battery tester patent. The patent taught a form of “dynamic” battery testing and each disputed term revolved around the meaning of “dynamic.” The Court adopted plaintiffs’ definition – varying over time – without limiting dynamic to require an AC current (a current that varies regularly over time). The Court held that requiring an AC current was an unnecessary limitation. Not all currents that vary over time are AC, and requiring an AC current would have read a preferred embodiment out of the claims.