When do patent claim preambles limit a claim?   Should an Applicant merely recite the statutory classification in the preamble (e.g., “an apparatus comprising” or “a method comprising”) without anything further, or should the patent practitioner include a limited description of the invention along with a statement of purpose?   What about statements of purpose or intended use that are included in a claim preamble?

Overview / General Rule

The Federal Circuit has held that “No litmus test defines when a preamble limits claim scope.”    Corning Glass Works v. Sumitomo Elec. U.S.A., Inc., 868 F.2d 1251, 1257, 9 USPQ2d 1962, 1966 More >