Whither the Reverse Doctrine of Equivalents

by Dennis Crouch

The Reverse Doctrine of Equivalents can shrink the scope of a patent to exclude acts literally covered by the claims.  The Supreme Court in Graver Tank explained that the doctrine comes up to prevent abuse of the patent system:

[W]here 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 doctrine of equivalents may be used to restrict the claim and defeat the patentee’s action for infringement.

Graver Tank & Mfg. Co., Inc. v. Linde Air Prods. Co., Inc., 339 U.S. 605 (1950).  The Graver Tank decision traced its provenance back to Westinghouse v. Boyden Power Brake Co., 170 U.S. 537 (1898) (“correspond[ence] with the letter of the [claim] does not settle conclusively the question of infringement.”).  Both Westinghouse and Graver Tank describe this scope-shrinking as an aspect of the doctrine of equivalents that can either increase or decrease literal scope.   The term “reverse doctrine of equivalents” was seemingly first used by Judge Markey in a 1977 decision rejecting application of any reverse doctrine of equivalents in the validity context. Ex parte Hogan, 559 F.2d 595, 607 (Cust. & Pat. App. 1977).   Hogan places the term within quotation marks–“reverse doctrine of equivalents”–but did not indicate whether those quotes were for emphasis or citing some prior usage. The usage was later solidified by the Federal Circuit in SRI International v. Matsushita Electrical Corp. of America, 775 F.2d 1107 (Fed. Cir. 1985).  In Roche Palo Alto LLC v. Apotex, Inc., 531 F.3d 1372 (Fed. Cir. 2008), the court endeavored to cabin-in the doctrine’s use by explaining that (1) “The reverse doctrine of equivalents is rarely applied”; and (2) the Federal Circuit “has never affirmed a finding of non-infringement under the reverse doctrine of equivalents.” Id.

The Reverse DOE has not seen much action of late.  In Steuben Foods, Inc. v. Shibuya Hoppmann Corp., CV 19-2181-CFC-CJB, 2021 WL 4775996, at *1 (D. Del. Oct. 13, 2021), the court denied summary judgment.  The defendant apparently admitted that its product was covered by the literal scope of the patent, but argued no infringement based upon the reverse doctrine of equivalents.  In particular, the defense argued that its sterile region was substantially different than that disclosed by the invention.  The jury was asked whether the accused machine “is no more than insubstantially different from the second sterile region of the invention.”  The jury marked the box labelled YES-INFRINGED.

Unlikely that the defendant will choose this issue to appeal given the history of the Federal Circuit and reverse DOE, but we’ll see.  In another recent Delaware decision, the court noted that Teva had initially raised the reverse doctrine of equivalents, but later dropped that defense.  Vifor Fresenius Med. Care Renal Pharma Ltd. v. Teva Pharm. USA, Inc., CV 18-390 (MN), 2022 WL 3562555, at *6 (D. Del. Aug. 18, 2022).  In, Kewazinga Corp. v. Microsoft Corp., 558 F. Supp. 3d 90, 112 (S.D.N.Y. 2021), the patentee sought summary judgment rejection of Microsoft’s reverse DOE defense. The district court refused, holding that any decision regarding reverse DOE must follow a finding regarding literal infringement. Id.

In many ways, the Reverse Doctrine of Equivalents has the potential of doing some of the same work as our doctrines of full-scope enablement & written description. A key difference though is that the outcome is a narrowed patent claim rather than an invalid patent claim.