At the Federal Circuit
Incorporation by Reference, the Doctrine of Equivalents, and the Disclosure-Dedication Rule
For the disclosure-dedication rule to bar infringement under the doctrine of equivalents (DOE), where the purportedly dedicated subject matter resides in a document incorporated by reference into a host patent, the host patent must provide sufficient notice that the incorporated document contains an alternative to a claim limitation. SanDisk Corp. v. Kingston Tech. Co., 695 F.3d 1348 (Fed. Cir. 2012). The DOE provides a basis for establishing infringement if an accused product or process does not literally meet a claim limitation but contains a feature equivalent to what is claimed. Several limitations restrict what can qualify as an infringing equivalent, including the disclosure-dedication rule. Under this rule, subject matter disclosed but not claimed by the patent is dedicated to the public, but only if the unclaimed subject matter was “identified by the patentee as an alternative to a claim limitation.” Pfizer, Inc. v. Teva Pharms., USA, Inc., 429 F.3d 1364, 1379 (Fed. Cir. 2005). In SanDisk, the Federal Circuit addressed the application of the disclosure-dedication rule when the purportedly dedicated subject matter is not in the actual patent’s text or drawings, but in another document incorporated by reference into the patent.
SanDisk appealed from summary judgment of noninfringement, contending that Kingston infringed a claim in U.S. Patent No. 6,149,316 to a computer memory system comprising, as relevant here, an array of memory cells and a controller connected to the array, wherein the controller comprises data reading and writing circuits. The parties did not dispute that the accused system contained data reading and writing circuits located not on the controller chip, but on a separate chip. A lack of any evidence that the circuits were somehow part of the controller despite this separation resulted in a finding of no literal infringement and turned the focus of the arguments to the DOE.
SanDisk asserted that the two chips in Kingston’s system (the controller and the separate chip with the data circuits) together constituted an equivalent of a single controller chip with data circuits. Kingston countered that the disclosure-dedication rule prevented infringement under the DOE. Specifically, the patent-in-suit incorporated U.S. Patent No. 5,172,338 (“the ’338 patent”) by reference, and the ’338 patent discloses the separate-chip arrangement employed by Kingston. Kingston therefore urged that the separate-chip arrangement was disclosed as an equivalent by the patent-in-suit but not claimed, barring application of the DOE to the separate-chip arrangement.
The court rejected Kingston’s argument. It acknowledged the possibility that subject matter in an incorporated document could be dedicated to the public for purposes of the host patent, but held that for dedication to occur, “the host patent must sufficiently inform one of ordinary skill that the incorporated document contains subject matter that is an alternative to a claim limitation.” SanDisk, 695 F.3d at 1366.
The court found that the host patent-in-suit did not identify the ’338 patent as containing an alternative to the recited controller. Specifically, the host patent only discussed the ’338 patent generally in two sentences regarding optimized erase implementations and optimized implementations of write operations for certain memory devices. The court held that this brief discussion did not provide sufficient notice that the ’338 patent contains an alternative to the recited controller. Therefore, the court vacated the district court’s summary judgment of no infringement under the DOE and remanded the case.
The SanDisk holding reduces the risk of undesired consequences from incorporating a document by reference into a patent specification. A contrary result may well have deterred incorporating documents by reference in many cases because the incorporated disclosure would have frequently foreclosed reliance on the DOE. Instead, the effect of incorporation on the DOE remains under the drafter’s control to a greater extent—the disclosure-dedication rule will likely not be triggered unless the host patent is written so as to identify alternatives in the incorporated document or otherwise provide notice that alternatives can be found there.
Although constructive notice seems unlikely as long as discussion of the incorporated document remains general, as demonstrated in SanDisk, the possibility that some form of constructive notice of alternatives could be recognized still merits caution when incorporating documents by reference. And, of course, drafters who find themselves identifying alternatives to a claim limitation may also wish to consider describing and claiming the alternatives literally in the text of the specification to avoid the litigation of DOE issues. Additionally, if a specification will be prosecuted internationally, describing the alternatives in the actual text and claiming them literally becomes more important because incorporation by reference and the DOE may not be available at all in foreign jurisdictions.