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As many fine practitioners will attest, there is a fine balance between the advantage of amending and arguing to win the day and the risks of saying too much, especially on record. There are two doctrines, arguably in opposition of one another, that govern such balance: the doctrine of equivalents (DOE) and the dedication disclosure doctrine (DDD).
First, let’s get on the same page with shared definitions of these doctrines.
Doctrine of Equivalents (DOE): a claim of patent infringement may arise even when each and every element of the patented invention is not identically present in the allegedly infringing product or process if the potentially infringing device performs substantially the same function in substantially the same way to obtain the same result.
Dedication Disclosure Doctrine (DDD): if subject matter is disclosed but not claimed, the patentee dedicates the unclaimed subject matter to the public and cannot recapture it through DOE. There are at least two ways to satisfy DDD, potentially negating the infringement claim:
1. Dedication-Disclosure Rule: alleged equivalent is disclosed in the specification but not claimed in the patent
2. Prosecution History Estoppel: alleged equivalent was surrendered during prosecution to obtain an allowance (e.g., by amending or argument)
Given the established tension between these doctrines, how does one maintain flexibility without saying too much?
Only argue amendments that need to be argued. In Warner-Jenkinson v. Hilton Davis Chemical Co., 520 U.S. 17 (1997), the claims were amended to recite “at a pH from approximately 6.0 to 9.0” and the accused process used pH 5.0. In the file history, the patentee only argued the upper limit, pH 9.0, to remove a prior art reference, whereas the reasoning behind the pH 6.0 amendment was unknown from the file history and the patentee could not recall any motivation for the amendment. As such, dedication disclosure doctrine did not apply to the lower pH limit of 6.0, only the upper pH limit of 9.0. See also Hubbell v. United States, 179 U. S. 77, 82 (1900).
Practical tip: if you can get away with saying less, then less is more in many arguments with the patent office. Consider interviews with the Examiner to express more while keeping less on record.
Identify or label steps of a method sequentially only when absolutely necessary. In Amgen Inc. v. Sandoz Inc. (Fed. Cir. 2019), the patentee claimed a three step process for preparing biologic products. Sandoz’s allegedly infringing process was argued as equivalent. However, the patentee, Amgen, sequentially listed the steps in the claims and sequentially described the steps in the specification. Accordingly, the doctrine of equivalents did not apply in this case; Sandoz’s process was not found to be equivalent via DOE.
Practical tip: do not numerically or alphabetically label steps in a method claim. Do include alternative methods in the specification that combine all or some of the method steps.
Separate embodiments than that which is claimed can still trigger DDD. In Eagle Pharmaceuticals Inc. v. Slayback Pharma LLC, No. 2019-1924 (Fed. Cir. May 8, 2020), the claimed mixture recited the pharmaceutically acceptable fluids of polyethylene glycol and propylene glycol. The allegedly infringing product (sold by Slayback) used ethanol as a pharmaceutically acceptable fluid. Eagle argued that DOE applied. Slayback argued that since Eagle recited in its specification, but did not claim, ethanol as a pharmaceutically acceptable fluid, Eagle dedicated ethanol to the public. In response, Eagle argued that ethanol was recited in a specific embodiment that was separate from the claimed embodiment, so that it could still be viewed as equivalent in the instant embodiment. However, the Federal Circuit rejected this embodiment by embodiment approach and ruled that the dedication disclosure doctrine applied to Eagle’s recitation of ethanol in the specification.
Practical tip: if there is cross use or equivalence of features from different embodiments, make sure that equivalence is explicit in the specification.
Given the variability of examiner and court interpretation, it’s impossible to derive a bullet proof formula to balance the tension between DDD and DOE, but there are some proven strategies that can, at least partially, future proof your patent application. Being mindful of the Doctrine of Equivalents and the Dedication Disclosure Doctrine can save you some potential heartache (and lost damages) in the future.
Ashley Sloat, Ph.D.
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