The US Court of Appeals for the Federal Circuit ruled that the “substantially the same way” comparison in connection with a doctrine of equivalents (DOE) analysis involving a means-plus-function claim limitation should focus on the overall structure corresponding to the claimed function, not on unclaimed structure. Steuben Foods, Inc. v. Shibuya Hoppmann Corp., Case No. 23-1790 (Fed. Cir. Jan. 24, 2025) (Moore, Hughes, Cunningham, JJ.)

Steuben Foods holds patents for an aseptic bottling system designed to sterilize and fill bottles with foodstuffs at speeds exceeding 100 bottles per minute, making the technology suitable for high-volume food production. Steuben sued Shibuya for infringing its patents. At trial, Steuben successfully demonstrated that Shibuya’s aseptic bottling system infringed a patent claim related to a “second sterile region,” a feature designed to pre-sterilize a valve mechanism and prevent contamination. The jury awarded Steuben more than $38 million in damages and, in doing so, rejected Shibuya’s defense under the reverse doctrine of equivalents (RDOE). The RDOE is a rarely invoked defense that is asserted when an accused product, although meeting the literal terms of a claim, operates on fundamentally different principles and thus does not infringe. Despite the jury’s verdict, the district court granted judgment as a matter of law (JMOL) of noninfringement, holding that Shibuya’s RDOE defense precluded infringement. Steuben appealed.

The Federal Circuit reversed the JMOL based on the RDOE, finding that the district court improperly weighed evidence that should have been left to the jury. The Court emphasized that Steuben’s expert testimony constituted substantial evidence supporting the jury’s findings and warranted deference. The Court also rejected Shibuya’s narrow construction of the claimed “second sterile region,” which would have excluded food flow, and affirmed the broader interpretation adopted by the district court (an interpretation the Court noted better aligned with the claim language).

The Federal Circuit noted that it had “previously described RDOE as an ‘anachronistic exception, long mentioned but rarely applied.’” While the Court declined to definitively rule on the RDOE’s continued viability under the Patent Act of 1952, it favorably noted Steuben’s argument that “if a device literally falls within the scope of a claim, but the accused infringer believes the claim is too broad and its device should not infringe, the appropriate recourse is a § 112 challenge, not a claim of noninfringement under RDOE.” In this case, the Federal Circuit concluded that even if Shibuya had made a prima facie case under RDOE that the principle of operation of the accused product was so far removed from the asserted claim, “the jury’s verdict should not have been overturned under RDOE because [Steuben’s expert] provided rebuttal testimony that the jury was entitled to credit. JMOL of noninfringement was therefore improper.”

The district court had also analyzed whether, under the DOE, claimed structures, such as conveyor plates and systems, were equivalent to Shibuya’s rotary wheels and neck grippers. The district court concluded they were not. The district court had construed the term “means for filling the aseptically disinfected plurality of bottles at a rate greater than 100 bottles per minute” as a means-plus-function limitation and identified the function as “[aseptically] filling the aseptically disinfected plurality of bottles at a rate greater than 100 bottles per minute.” The corresponding structure was identified as filling valves, filling nozzles, “a control system, a conveyer plate, conveyor, and equivalents.” In granting JMOL, the district court concluded that no reasonable juror could find that “the way the accused machines’ rotary wheels and neck grippers operate in substantially the same as the way a conveyor and conveyor plate.” However, the Federal Circuit reversed, finding substantial evidence in Steuben’s favor. Steuben’s expert testified that although the accused structures differed in form, they performed the same function – moving bottles for filling – using a substantially similar method.

Steuben also argued that Shibuya’s continuous sterilization process was functionally equivalent to the intermittent sterilization described in the patent. Steuben’s expert testified that both methods ensured adequate sterilant delivery to the bottles, achieving equivalent sterilization outcomes. Despite this testimony, the Federal Circuit upheld the district court’s decision on this point, noting that the parties had stipulated to a claim construction of “intermittently added” as “[a]dded in a non-continuous matter.” Reasoning that something that is done non-continuously cannot be the equivalent of something done continuously, the Court concluded that any finding of infringement under DOE would vitiate the stipulated claim limitation.

Shibuya also sought a new trial on the validity of the asserted patents but failed to comply with Rule 50(a), which requires that such motions first be made at trial. Consequently, the district court denied Shibuya’s Rule 50(b) motion on validity, but conditionally granted a new trial without providing specific reasoning. On appeal, Steuben argued that the new trial should have been denied, while Shibuya contended that the jury’s validity verdict was against the weight of the evidence. The Federal Circuit vacated the district court’s conditional grant of a new trial, citing its failure to provide a rationale, and remanded the case for further proceedings.