"Comprised of" and "Comprising" Are Open Claim Transitions

Cias, Inc. v. Alliance Gaming Corp., [2006-1342](September 27, 2007)[NEWMAN, Schall, Moore] The Federal Circuit affirmed grant of summary judgment of non-infringement of U.S. Patent No. 5,283,422, despite the district court's error in construing the term "comprised of".
SIGNIFICANCE: 1. "Comprised of" usually means the same thing as "comprising" in a claim transition. 2. Claims can be limited by arguments about the prior art, even if there was no rejection of the claim.
BRIEF: The claims of a patent establish and limit the patentee's right to exclude, by "describing the outer boundaries of the invention." Claim 1 included the transition "comprised of".
Patent claims are construed as they would be understood by a persons experienced in the field of the invention, on review of the patentee's description of the invention in the specification and the proceedings in the Patent and Trademark Office. The district court interpreted "comprised of" as being narrower than comprising. The Federal Circuit said this ruling was not correct. "Although 'comprised of' is not used as regularly as 'comprising,' and 'comprised of' is sometimes used other than as a 'transition phrase,' nonetheless it partakes of long-standing recognition as an open ended term." The Federal Circuit added that "[t]he usual and generally consistent meaning of 'comprised of,' when it is used as a transition phrase is, like 'comprising,' that the ensuing elements or steps are not limited." In other words, the conventional usage of "comprising" generally also applies to "comprised of." However the fact that the claim was open did not allow the patentee to recapture additional elements that were expressly disclaimed during prosecution of the reexamination. In the reexamination, the patentee made certain arguments about differences from the Shoshani, and even though the claims were not rejected of Shoshani, the Federal Circuit agreed that a disclaimer nonetheless occurred/