The Reverse Doctrine of Equivalents is Alive, but Not Well

In its recent decision in Steuben Foods, Inc. v. Shibuya Hoppmann Corp., 2023-1790 (Fed. Cir., 2025), the Federal Circuit, while not directly addressing whether the reverse doctrine of equivalence (RDOE) is a valid defense to infringement, strongly suggests that would-be infringers should not rely on RDOE as a defense to patent infringement.

The RDOE is a judicially-created defense to infringement that is, as its name indicates, the inverse of the more popular doctrine of equivalents (DOE). Many practitioners will recognize DOE as extending infringement beyond the literal scope of a patent claim where the alleged infringing device, process, etc. “performs substantially the same function in substantially the same way to obtain the same result.”[1] However, in addition to the sword established by the DOE, the Supreme Court crafted a shield for defendants in the RDOE.

The wholesome realism of this doctrine [of equivalents] is not always applied in favor of a patentee but is sometimes used against him. Thus, where a device is so far changed in principle from a patented article that it performs the same or a similar function in a substantially different way, but nevertheless falls within the literal words of the claim, the [reverse] doctrine of equivalents may be used to restrict the claim and defeat the patentee's action for infringement.[2]

In Steuben Foods, the District of Delaware granted Shibuya’s petition for a judgment of non-infringement as a matter of law (JMOL) based on Shibuya’s RDOE defense. Steuben appealed the JMOL asserting, in part, that RDOE is not a valid defense in view of the 1952 Patent Act.

Steuben argued that the 1952 Patent Act was drafted as a direct result of the Court’s opinion in Graver Mfg. and that the plain language of 35 U.S.C. § 271(a) requires that exceptions to infringement must be expressly identified in Title 35, which does not recognize RDOE. According to Steuben, § 112 of the 1952 Patent Act provides recourse for a defendant if it believes that a patent claim is too broad and its device does not infringe, even though the device may fall within the broad, literal scope of the patent claim. The Federal Circuit had previously made a similar conclusion stating, “written description, enablement, definiteness, and means-plus-function claims [] are co-extensive with the broadest possible reach of the reverse doctrine of equivalents.”[3]

Shibuya’s rebuttal to Steuben’s argument was the Supreme Court held that the 1952 Patent Act “left intact the entire body of case law on direct infringement,” which Shibuya contended includes RDOE.[4]

In dicta the Federal Circuit stated, “We find Steuben’s arguments compelling, but need not decide whether RDOE survived the 1952 patent Act.”[5] In addition, it was noted that the Federal Circuit had never affirmed a decision of non-infringement based on the RDOE.[6] Therefore, Steuben Foods did not eliminate RDOE as a defense to infringement in Steuben Foods, but it cast a dark, if not deadly, shadow on the effectiveness of RDOE.

Ultimately, the court reversed the district court’s JMOL of non-infringement by finding that the district court erred in not considering RDOE rebuttal testimony provided by Steuben’s expert.

Although Steuben Foods did not explicitly eliminate RDOE as a defense to patent infringement, the Federal Circuit’s opinion made clear that RDOE is not a defense to be relied upon.  Instead, defendants should look to 35 U.S.C. §112 enablement and written description for arguments to limit the claim scope and assert that the alleged infringing product or process is not an equivalent to the claimed subject matter.

If you have any questions, please contact the author or your Dinsmore attorney.