by Dennis Crouch
I have been following the Steuben Foods appeal for the past year – thinking that it may be the case where the Federal Circuit nails in the coffin on the reverse doctrine of equivalents. The new decision ultimately left this question open, but it provides a fascinating exploration of three distinct doctrines of equivalence in patent law:
- The Reverse Doctrine of Equivalents (RDOE): This centuries-old defense, originating from the Supreme Court’s 1898 Boyden Power-Brake decision, allows an accused infringer to escape liability even when their device falls within the literal scope of the claims. A key question here was whether this doctrine even survived the 1952 Patent Act.
- The Doctrine of Equivalents (DOE): This traditional doctrine allows patent holders to prove infringement even when the accused device falls outside the literal scope of the claims. In this case, the court examined whether continuous sterilant addition could be equivalent to intermittent addition.
- Means-Plus-Function Equivalents: Under 35 U.S.C. § 112(f), means-plus-function claims cover not only the corresponding disclosed structure but also its equivalents. The court here analyzed whether rotary wheels could be equivalent to the disclosed conveyor structures.
The dispute centered on patents related to aseptic bottling technology – specifically, systems for sterilizing and filling bottles with food products. Steuben Foods alleged that Shibuya’s P7 aseptic bottling line infringed multiple patents, including U.S. Patent Nos. 6,209,591, 6,536,188, and 6,702,985. After a five-day trial, a jury found infringement of all asserted claims and awarded Steuben over $38 million in damages. The district court subsequently granted judgment as a matter of law (JMOL) of noninfringement on all patents. For the ‘591 patent, the court relied on the reverse doctrine of equivalents – a defense that has never been successfully used to affirm noninfringement in Federal Circuit history.
RDOE: The reverse doctrine of equivalents traces its origins to the Supreme Court’s 1898 decision in Boyden Power-Brake Co. v. Westinghouse, 170 U.S. 537 (1898). In that case, Westinghouse had accused Boyden’s brake system of infringed its patents covering “quick-action” air brakes. The Court found that while Boyden’s device fell within the literal scope of Westinghouse’s claims, it operated on a substantially different principle by using a unique partition system to create differential pressure. The court concluded that the new product could not fairly be said to infringe because the accused infringer “has so far changed the principle of the device that the claims of the patent, literally construed, have ceased to represent his actual invention.” Id. The Supreme Court last discussed RDOE in Graver Tank & Mfg. Co. v. Linde Air Products Co., 339 U.S. 605 (1950), noting once again that while the doctrine of equivalents could expand patent coverage beyond literal claim scope, RDOE could restrict claims that were literally infringed. Specifically addressing RDOE, the Court repeated the Westinghouse doctrine that “where a device is so far changed in principle from a patented article that it performs the same or similar function in a substantially different way, but nevertheless falls within the literal words of the claim, the doctrine of equivalents may be used to restrict the claim and defeat the patentee’s action for infringement.” The Court cited Westinghouse v. Boyden Power-Brake Co. as precedent for this principle, though Graver Tank itself ultimately turned on regular doctrine of equivalents rather than RDOE, finding infringement based on equivalency between manganese and alkaline earth metals in welding flux compositions. The Federal Circuit has characterized RDOE as an “anachronistic exception, long mentioned but rarely applied”, and indeed since its creation in 1982 the Federal Circuit has never affirmed a finding of non-infringement based on RDOE.
In its briefing, Steuben presented a novel argument that RDOE did not survive the 1952 Patent Act, pointing to the plain language of 35 U.S.C. § 271(a) requiring exceptions to infringement be “expressly identified in Title 35.” Steuben further argued that § 112’s written description, enablement and definiteness requirements subsumed RDOE’s function.
The Federal Circuit opinion, authored by Chief Judge Moore and joined by Judges Hughes and Cunningham, found Steuben’s arguments “compelling,” but ultimately the appellate panel declined to resolve the issue definitively. Instead, the court reversed the JMOL by finding substantial evidence supported the jury’s rejection of the RDOE defense based on conflicting expert testimony regarding the principles of operation.
The opinion also addressed equivalents along two other fronts:
DOE: The jury found some claims infringed under the doctrine of equivalents, but the district court granted JMOL of non-infringement. The basic issue is that the claims require intermittent addition of a sterilant, but the accused device adds it in a continuous fashion. The appellate court affirmed that JMOL was appropriate – finding that the claimed intermittent method is the antithesis of continuous. DOE cannot apply if it entirely vitiates the meaning of the claimed “limitation.”
The Federal Circuit distinguished this case from its prior decision in Epos Techs., Ltd. v. Pegasus Techs. Ltd., 766 F.3d 1338 (Fed. Cir. 2014), where it had found that continuous and intermittent operations could potentially be equivalent. The key difference was that in Epos, the parties had not agreed to a construction that explicitly defined intermittent in opposition to continuous operation. The court’s analysis here thus reinforces a principle that claim construction can effectively cabin the scope of equivalents available under the doctrine of equivalents. Even though Steuben’s expert Dr. Sharon testified that continuous sterilization achieved the same “function, way, and result” as intermittent addition, this equivalence theory could not overcome the definitional barrier created by the stipulated construction.
The court’s holding illustrates an important limit on the doctrine of equivalents – it cannot be used to eliminate a claim limitation entirely, even if the accused product achieves the same ultimate purpose through different means. While the doctrine serves to prevent “fraud on a patent” by preventing only minor variations from avoiding infringement, see Graver Tank & Mfg. Co. v. Linde Air Products Co., 339 U.S. 605, 608 (1950), it must still preserve the meaning of claim limitations. Where, as here, the parties’ agreed construction sets up a direct opposition between the claimed limitation and the accused structure, finding equivalence would impermissibly expand the scope of the claims beyond their meaning. The court found that no reasonable jury could conclude that continuous addition was equivalent to intermittent addition when intermittent was defined as non-continuous.
The Federal Circuit’s analysis lost sight of the forest for the trees by focusing too narrowly on the isolated phrase “intermittently added” rather than considering the full context of the claim element “atomized sterilant is intermittently added to said conduit.” When viewed at the appropriate element level – the entire mechanism and process of adding atomized sterilant to the conduit – Shibuya’s continuous addition could reasonably be seen as an insubstantial variation that achieves the same sterilization function through a slightly different timing approach, rather than the “antithesis” of the claimed element. This broader perspective aligns with the fundamental purpose of the doctrine of equivalents to prevent “fraud on a patent” by ensuring that minor variations in how an element is implemented cannot avoid infringement when the accused product achieves substantially the same result in substantially the same way. See Graver Tank & Mfg. Co. v. Linde Air Products Co., 339 U.S. 605 (1950).
MPF: The third and final equivalents focus in the case is the appellate panel’s means-plus-function analysis. If you recall, 112(f) states that a means plus function claim should be construed to cover the corresponding structure disclosed in the specification as well as equivalents of that structure. Here, the court uses the same DOE analysis to find equivalents: identical function as that claimed, in substantially the same way as the structures disclosed, with substantially the same result. Here, the court found substantial evidence supported equivalence between the claimed conveyor/conveyor plate structures and the accused rotary wheels/neck grippers because both sets of structures achieved the claimed function of “filling the aseptically disinfected plurality of bottles at a rate greater than 100 bottles per minute.”
The Federal Circuit’s analysis also clarified an important principle regarding the granularity of means-plus-function analysis – that differences in structure must be evaluated in the context of the claimed function rather than in isolation. As the court explained, “[t]he individual components, if any, of an overall structure that corresponds to the claimed function are not claim limitations. Rather, the claim limitation is the overall structure corresponding to the claimed function.”