In Steuben Foods, Inc. v. Shibuya Hoppmann Corporation, the Federal Circuit issued a major decision addressing key intellectual property issues related to patent infringement, claim construction, and the reverse doctrine of equivalents (RDOE). The case centered on aseptic food packaging technology, with the court analyzing whether Shibuya’s P7 aseptic bottling line infringed Steuben’s patents.
This ruling highlights several crucial aspects of IP law, including the viability of RDOE as a defense, the interpretation of means-plus-function claims, and the application of the doctrine of equivalents. Below, we break down the major legal takeaways from this case.
1. The Reverse Doctrine of Equivalents is Questioned but Not Eliminated
One of the most significant aspects of the ruling was the court’s discussion of RDOE, an uncommon defense to literal infringement. Shibuya argued that even if its product fell within the literal scope of Steuben’s patent claims, it operated under a different principle and should not be found infringing.
Steuben countered that RDOE was effectively eliminated by the 1952 Patent Act, which codified infringement rules in 35 U.S.C. § 271(a) and included limitations on overly broad claims under § 112. The Federal Circuit acknowledged that RDOE has been rarely applied and that there is an argument that it may no longer be viable. However, rather than making a definitive ruling on whether RDOE survived the 1952 Patent Act, the court found that the jury had substantial evidence to reject Shibuya’s RDOE argument. As a result, the court reversed the district court’s judgment as a matter of law (JMOL) and reinstated the jury’s infringement verdict for the ‘591 patent.
2. Means-Plus-Function Claims and the Equivalence Test
Another key issue involved the construction of means-plus-function claims in the ‘188 patent. The claims at issue used functional language to describe components of the aseptic filling system, such as a “means for filling” bottles at a specified rate. Under § 112, ¶ 6, such claims must be construed to cover the specific structures disclosed in the patent and their equivalents.
The district court had found that Shibuya’s accused products, which used rotary wheels and neck grippers, did not infringe the means-plus-function claims because they operated differently from the patented conveyor and conveyor plate. However, the Federal Circuit reversed, emphasizing that the equivalence test must consider whether the accused structure performs the same function in substantially the same way to achieve the same result. The court found that Steuben presented substantial evidence that Shibuya’s rotary wheels and neck grippers were equivalent to the claimed structures, leading to a reinstatement of the jury’s verdict on the ‘188 patent.
3. Limits on the Doctrine of Equivalents
The court upheld JMOL of noninfringement for claims in the ‘985 patent, highlighting an important limitation on the doctrine of equivalents. The issue in this case was whether a sterilization system that added sterilant “continuously” could be deemed equivalent to a claim that required it to be added “intermittently.”
The parties had stipulated that “intermittently added” meant “[a]dded in a non-continuous manner.” Given this definition, the court held that allowing a “continuous” system to be considered equivalent would vitiate the claim limitation entirely. This ruling reinforces the principle that the doctrine of equivalents cannot be used to erase clear claim limitations.
4. Reinstating the Jury’s Verdict and Addressing New Trial Issues
In addition to reversing JMOL on certain infringement claims, the Federal Circuit also vacated the district court’s conditional grant of a new trial on infringement and damages. Because the district court’s reasoning for ordering a new trial was tied to its JMOL findings—many of which were overturned—the Federal Circuit found no independent basis for a new trial.
However, the court vacated and remanded the district court’s ruling on a new trial for invalidity and damages, as the lower court had provided no clear rationale for those decisions. This signals the importance of district courts articulating their reasoning clearly when granting new trials, especially in complex patent litigation.
Key Takeaways for Patent Holders and Defendants
This decision offers several key lessons for patent holders and defendants in intellectual property disputes:
- RDOE Remains a Questionable Defense – While the court did not rule on whether RDOE survived the 1952 Patent Act, it reinforced the principle that substantial evidence from a jury trial should not be overturned lightly.
- Means-Plus-Function Claims Require Proper Equivalence Analysis – When dealing with § 112, ¶ 6 claims, courts must carefully compare the structure and function of the accused product to the patent’s disclosed embodiments.
- Doctrine of Equivalents Has Limits – The decision confirms that the doctrine of equivalents cannot be used to override explicit claim limitations, particularly when the alleged equivalent is the opposite of the claim language.
- District Courts Must Provide Clear Justifications for New Trials – The Federal Circuit vacated a new trial ruling because the district court failed to articulate an independent basis for it.
Conclusion
The Steuben Foods decision provides important guidance on several areas of intellectual property law, particularly for companies engaged in patent disputes over manufacturing processes. While the Federal Circuit did not eliminate RDOE outright, it cast doubt on its viability, reinforcing that patentees should focus on claim construction and infringement theories rather than relying on outdated doctrines. The ruling also strengthens the application of means-plus-function claims and the doctrine of equivalents while ensuring that district courts justify their decisions with clear reasoning.
As patent litigation continues to evolve, this case serves as a reminder of the complexities of IP law and the need for strategic approaches in patent enforcement and defense.
By Charles Gideon Korrell