Primos, Inc. v. Hunter’s Specialties, Inc., et al.
Primos had filed suit in 2001 against Hunter’s Specialties for infringement of two of Primos’s “game call” patents. On appeal from the District Court for the Northern District of Iowa, the CAFC affirmed the construction of the term “engaging” in finding literal infringement of U.S. Pat. No. 5,520,567 (the ‘567 patent), and also found infringement of U.S. Pat. No. 5,415,578 (the ‘578 patent) under the doctrine of equivalents.
The relevant claim in the ‘578 patent recited “. . . a second roof-of-mouth engaging portion extending upwardly from the frame . . . .” The relevant claim in the ‘567 patent recited “. . . a plate having a length, the plate extending generally upward from the frame . . . .” The accused device sold by Hunter’s was a diaphragm mouth call device having a dome (not a plate) extending above a membrane.
I. Claim Construction
Hunter’s argued that the court erred in construing the term “engaging” to mean “to come into contact with”, and rather that the term should be construed to mean “a seal created between the edge of the frame and the roof of the user’s mouth” or “interlocking.” In support of the argument, Hunter’s cited other claim language, the specification description of the “edge as sealing against the roof of a mouth,” and in particular a dictionary definition of the term “engaging.”
In following the decision of Phillips v. AWH Corp., the court stated that the primary focus should be on the intrinsic evidence of record, i.e. the claims, specification, and prosecution history. Since the term “engaging” was not expressly mentioned in the text of the specification, the CAFC turned to Figures 1 and 3 for the claim construction analysis. The court held that the figure discouraged a construction of “interlocking” and that to interpret the claim so would be to exclude the particular embodiments shown in the figures. Thus, the district court’s construction of the term engaging was held to be supported by the intrinsic record.
II. Doctrine of Equivalents
Hunter’s argued that the amendments to the term “plate” constituted grounds for prosecution history estoppel, thus barring the doctrine of equivalents for the term. As stated in Festo Corp. v. Shoketsu, when a patent claim is amended during prosecution for reasons relating to patentability, there is a presumption that the patentee surrendered all the territory between the original claim limitation and the amended claim limitation. An exception, however, is when the “rationale underlying the amendment may be no more than a tangential relation to the equivalent in question.”
The court found that the term “plate” was amended to require it having a length and to add the limitation that the plate be “differentially spaced” above the membrane. The “length” amendment did not narrow scope because every physical object has a length. With respect to the “differentially spaced” amendment, the court held that the limitation did not pertain to the disputed element in the accused device, and thus was merely tangential. Accordingly, prosecution history estoppel did not preclude the application of the doctrine of equivalents.
Hunter’s also argued under the “all limitations rule” considering a dome to be equivalent to a plate would vitiate the claim limitation. The “all limitations rule” restricts the doctrine by preventing its application when doing so would vitiate (or eliminate) a claim limitation. The CAFC upheld the district court’s ruling that application of the doctrine was not improper in this case. Courts must considered the totality of circumstances and determine whether the alleged equivalent can be fairly characterized as an insubstantial change from the claimed subject matter without rendering the pertinent limitation meaningless. Thus, as application of the doctrine to this case did not effectively eliminate the plate limitation in its entirety, the “all limitations rule” was not violated.
III. Additional Issues
In addition to the claim construction and doctrine of equivalents issues noted above, the court also summarily addressed Hunter’s arguments with respect to exclusion of evidence and adverse-inference jury instructions. I’ve decided not to discuss them, but feel free to check out the opinion if these issues interest you.