Although technically dicta based on the reversal of the underlying literal construction, the court went out of its way to note that “[t]he district court’s treatment of the doctrine of equivalents reveals a common misperception regarding ‘vitiation’ that warrants some discussion.” The proper inquiry under the doctrine of equivalents is simply whether an asserted equivalent represents an “insubstantial difference” from the claimed element, or “whether the substitute element matches the function, way, and result of the claimed element.” For “vitiation” to apply and bar equivalency, the element at issue must really be the “antithesis” of the claimed structure. Evidently, direct and indirect couplings are not the antithesis of each other, especially when one or the other is read into the claim by the court’s construction.
Background / Facts: The patent at issue was directed to an “easy clean dual wall deck” for a rotary cutter, the type that is pulled behind a tractor and used to mow wide swaths of ground. The dual-wall deck encloses the structural components of the cutter in a torsionally-strong box, leaving smooth surfaces on the top and bottom of the deck to make it easier to clean. The dual-wall design is claimed as upper and lower deck walls that come “into engagement with” one another. The district court construed the term “into engagement with” to require direct contact between the upper and lower deck walls, and held that this construction foreclosed indirect contact equivalency (as in the accused devices) because the literal construction “specifically excludes structures where the deck walls are not engaged with each other.”
Issue(s): Whether it is appropriate to shortcut the doctrine of equivalents inquiry by identifying a “binary” choice in which an element is either present or “not present.”
Holding(s): No. The vitiation test cannot be satisfied by simply noting that an element is missing from the claimed structure or process because the doctrine of equivalents, by definition, recognizes that an element is missing that must be supplied by the equivalent substitute. If mere observation of a missing element could satisfy the vitiation requirement, this “exception” would swallow the rule. In this case, the district court construed “contact” to require “direct contact,” and thus found that allowing “no direct contact” would vitiate the court’s construction. Yet, a reasonable jury could find that a small spacer connecting the upper and lower deck walls represents an insubstantial difference from direct contact. (Nevertheless, the court held that the ordinary meanings of the terms that describe the relationship between the upper and lower deck walls – “cooperate,” “join[ ],” “engage[ ]” – do not necessitate direct contact, and that the literal construction underlying the doctrine of equivalents error was likewise erroneous.)