Recent Federal Circuit Case Sheds Light on Use of Terms of Degree and/or Relative Terms in Claims

The Federal Circuit’s recent decision in Grace Instrument Industries, LLC (Grace) v. Chandler Instruments Co. (Chandler)[1] provides useful guidance for patent practitioners seeking to use a term of degree and/or a relative term in their claims to protect an invention.

Grace, the owner of U.S. Patent No. 7,412,877 (the ‘877 patent), appeals a claim construction order finding the term “enlarged chamber” indefinite and construing the term “means for driving said rotor to rotate located in at least one bottom section.”[2]

The first half of the Federal Circuit’s opinion considers whether a term of degree, which does not include a baseline for comparison within the claim, is indefinite. At the district court level, the term “enlarged chamber” was found to be indefinite on the basis that “enlarged” is a term of degree which requires a comparison against a baseline to understand the scope of the claims.[3]

The Federal Circuit vacated the district court’s finding and held that in the context of this patent, “enlarged chamber” does not require the chamber to be larger than some baseline object but rather it must be large enough to accomplish a particular function.[4] The Federal Circuit agreed with Grace, that the term “enlarged chamber” of the claimed viscometer should be construed as “large enough to hold excess test sample (i.e., the type of fluid normally used in these machines) to prevent mixing of pressurization fluid and test sample below the bottom fin during elevated pressurization.”[5]

Notably, the specification of the ‘877 patent refers to “enlarged chamber” only twice and a definition was not explicitly provided in the specification.[6] However, the Federal Circuit held that a “claim term may be clearly redefined without an explicit statement of redefinition,” and “[e]ven when guidance is not provided in explicit definitional format, the specification may define claim terms by implication such that the meaning may be found in or ascertained by a reading of the patent documents.”[7] The Federal Circuit seemed particularly persuaded in favor of the patentee due to a compelling problem/solution narrative within the specification of the ‘877 patent, which described the state of the art at the time of the invention and described how the disclosed new design of the viscometer solved the shortcomings of the prior art.[8]

The second half of the Federal Circuit’s opinion evaluates the District Court’s claim construction of the term “means for driving said rotor to rotate located in at least one bottom section.” More particularly, infringement hinged on whether the phrase “located in at least one bottom section” was construed to modify “means for driving” or construed to modify “said rotor.”[9]

The District Court adopted Chandler’s proposed claim construction, that the phrase “located in at least one bottom section” modifies “means for driving” rather than “rotor.”[10] Upon review, the Federal Circuit confirmed[11] The Federal Circuit starts with the claim language itself and finds that the most natural reading of the claim limitation requires the phrase “located in at least one bottom section” to modify “means for driving” and not “rotor.”[12] The Federal Circuit reasons that if the patentee had intended for “located in at least one bottom section” to modify “rotor,” the patentee would have placed the “located in at least one bottom section” phrase before “to rotate.”[13] Further, the Federal Circuit reasons that it would make little sense for a claim limitation to introduce the rotor as located in the pressure vessel, and then, in a separate limitation directed to the “means for driving,” explain that the rotor is located in the bottom section [14].

The Grace decision illustrates that a functional purpose and a compelling problem/solution narrative within the specification may be effective tools for a patent practitioner to utilize when facing an indefiniteness rejection of a term of degree before the USPTO. The Grace decision further illustrates that when using a relative term in a claim, patent practitioners should take care to define what the relative term is referencing within the claim.

[1] Grace Instrument Industries, LLC v. Chandler Instruments Co., 2021-2370, Fed. Cir., January 12, 2023.
[2] Id. at page 2.
[3] Id. at page 7.
[4] Id. at page 16.
[5] Id. at pages 11, 16.
Id. at pages 13, 14.
[7] Id. at page 14, first quoting Bell Atl. Network Servs., Inc. v. Covad Commc’ns Grp., Inc., 262 F.3d 1258, 1268 (Fed. Cir. 2001) and then quoting Irdeto Access, Inc. v. Echostar Satellite Corp., 383 F.3d 1295, 1300 (Fed. Cir. 2004).
[8] Id. at pages 11, 12.
[9]Id. at page 17.
[10] Id. at page 8.
[11] Id. at page 17.
[12] Id.
[13] Id.
[14] Id. at page 18.