Infringement under the doctrine of equivalents is not foreclosed simply by the claimed limitation being the literary “antithesis” of the accused infringer’s corresponding feature. Here, for example, no substantial difference was found between deoxygenating before or after forming a given solution even though the terms “before” and “after” are literarily-speaking the antithesis of each other. “The determination of equivalence depends not on labels like ‘vitiation’ and ‘antithesis’ but on the proper assessment of the language of the claimed limitation and the substantiality of whatever relevant differences may exist in the accused structure.”
Background / Facts: The patents being asserted here are directed to aqueous phenol solutions—particularly acetaminophen. The claims recite deoxygenation of an acetaminophen-containing solution by bubbling with at least one inert gas and/or placing under vacuum, until the oxygen content is below 2 ppm. Although the accused infringer does not literally infringe because their solvent is deoxygenated before rather than after the active ingredient has been dissolved, a distinction that the accused infringer characterizes as the “antithesis” of the limitation at issue, the district court found infringement under the doctrine of equivalents.
Issue(s): Whether reducing the amount of dissolved oxygen to below 2 ppm before acetaminophen is added would vitiate the claim element requiring reduction of the dissolved oxygen content after acetaminophen is added.
Holding(s): No. “[The patentee] fundamentally misunderstands the doctrine of claim vitiation. ‘Vitiation’ is not an exception or threshold determination that forecloses resort to the doctrine of equivalents, but is instead a legal conclusion of a lack of equivalence based on the evidence presented and the theory of equivalence asserted. We have repeatedly reaffirmed this proposition. [] Characterizing an element of an accused product as the ‘antithesis’ of a claimed element is also a conclusion that should not be used to overlook the factual analysis required to establish whether the differences between a claimed limitation and an accused structure or step are substantial vel non. The determination of equivalence depends not on labels like ‘vitiation’ and ‘antithesis’ but on the proper assessment of the language of the claimed limitation and the substantiality of whatever relevant differences may exist in the accused structure.”