By Dennis Crouch
John Deere v. Bush Hog (Fed. Cir. 2012)
When I was a kid, we had a "John Deere Bush Hog" for mowing pasture land (AKA "bush hogging"). Several years later I learned that we really had a John Deere brand rotary cutter. The Bush Hog company also sells its own brand of rotary cutter. In this case, Deere sued Bush Hog for infringing its U.S. Patent No. 6,052,980. That patent claims a deck for a rotary cutter that is more easily cleanable.
One claim limitation required that an upper deck wall be sloped "rearwardly from said central portion into engagement with, and being secured to, said lower deck wall." Apparently in the accused Bush Hog device, the upper deck wall does not directly contact the lower deck wall. As per usual, that infringement issue was posed as a claim construction question determined by the judge as a matter of law. Here, the district court judge ruled that the "into engagement with" limitation required direct contact and that there could therefore be no literal infringement of the claim. When pressed on the doctrine of equivalents, the district court revived the vitiation exception to the DOE and ruled that the claims could not be extend to cover no direct contact when they claim the exact opposite of direct contact.
On appeal, the Federal Circuit doubly rejected the district court opinion.
On claim construction, the court ruled that "engagement" between two metal sheets does not require direct contact, but may instead be facilitated through indirect contact. The court demonstrated this conclusion with reference to a drawing from the Deere patent where a filler plate (shown in blue) provides the engagement between the upper deck (yellow) and the lower deck (red).
On Vitiation of the Doctrine of Equivalents: Although dicta, Judge Rader continued his opinion a repudiation of the district court's mistreatment of the vitiation doctrine. Of course, the doctrine is regularly mistreated because it is lacking in logical sense. The doctrine of equivalents allows a patentee to capture some amount of scope that goes beyond the literal scope of the claims as written. As a matter of course, this always involves rejecting the literal bounds created by one or more claim limitation. However, the doctrine of vitiation rises to stop a patentee from applying the DOE in a way that negates the meaning of one or more claim term. In his opinion, Chief Judge Rader attempts to cut through this knot and cautions against the programmatic use of the vitiation doctrine:
Courts should be cautious not to shortcut this inquiry by identifying a "binary" choice in which an element is either present or "not present." Stated otherwise, 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. . . . [P]reserving the doctrine in its proper narrowed context requires a court to examine the fundamental question of whether there is a genuine factual issue that the accused device, while literally omitting a claim element, nonetheless incorporates an equivalent structure.
Chief Judge Rader goes on to explain how the suggested use of the DOE in this case likely does not vitiate the relevant claim terms.
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. See TurboCare Div. of Demag Delaval Turbomachinery Corp. v. Gen. Elec. Co., 264 F.3d 1111, 1124 (Fed. Cir. 2001) (construing claim term "contact" to require "touching" but remanding question of whether "indirect contact" could be equivalent). Thus, the trial court erred by invoking the vitiation
Rader's basic idea here an attempt to move away from the technical limitations that have pushed the DOE toward obscurity over the past several years. In his view, vitiation should not be seen as a technical doctrine but instead simply a tool for district courts to use when the claim language is so far from the asserted equivalent that no reasonable jury would find infringement.
On remand, the new claim construction breathes new life into Deere's infringement case.