The US Court of Appeals for the Federal Circuit held that the disclosure of an added function in the specification of a patent should not affect the structure necessary to meet the recited function in a Section 112(f) claim element. Gramm v. Deere & Co., Case No. 24-1598 (Fed. Cir. Mar. 11, 2026) (Lourie, Reyna, Cunningham, JJ.)

Richard Gramm exclusively licensed Reaper Solutions rights to a patent directed to an apparatus for keeping the header of a crop harvester at a certain height above the ground as the harvester moves across a field. Gramm and Reaper sued Deere & Co., alleging that specific Deere header sensor kits infringed the patent. Deere challenged the validity of the patent in a partially successful inter partes review (IPR) proceeding, leaving one independent claim and some of the dependent claims asserted.

In connection with claim construction during the IPR proceeding, Reaper and Deere disputed the meaning of “control means” in the independent claim. At issue was whether the specification’s discussion of the “head controller 20” was sufficiently definite corresponding disclosed structure for the (§112(f)) means-plus-function claim element to satisfy the definiteness requirement of §112 (b). The function of the claimed “head controller” was to provide electrical control signals to another feature in the claimed apparatus to control the lateral position of the corn header and its height above the ground or soil. Deere argued that “head controller 20” was not sufficiently definite since it amounted to a general-purpose computer or processor, thus requiring disclosure of code or an algorithm to avoid being indefinite.

In 1997, the patent’s priority date, there were only three commercially available head controllers used in Deere combines: Dial-A-Matic Versions #1, #2, and #3. Deere argued that only Versions #2 and #3 could constitute corresponding structure for the “head controller 20,” as only those versions could control both header height and lateral position. Because Versions #2 and #3 used microprocessors to control header height, Deere argued that the patent specification was required to disclose an algorithm for performing the claimed function. In the alternative, Deere argued that the district court should hold Reaper to its argument in the IPR proceeding that the corresponding disclosed structure was the specific controller incorporated into Deere’s Dial-A-Matic Version #1, which “controlled header height through a series of diodes, switches and integrated circuits rather than a microprocessor.”

The district court found the independent claim indefinite and reasoned that the specification’s reference to Dial-A-Matic Versions #2 and #3 triggered the need for a disclosure of a general-purpose computer or microprocessor that the patent failed to satisfy. The district court accepted Deere’s argument that the specification did not disclose Dial-A-Matic Version #1 as a corresponding structure because it could not perform the function of controlling the lateral position of the corn header. Reaper appealed.

The Federal Circuit agreed with Reaper that the district court erred by identifying a corresponding structure for “control means” beyond what was necessary to perform the claimed function, leading the district court to incorrectly [...]

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