Federal Circuit Decision Highlights Seldom-Used Doctrine Of Equivalents Analysis

The Federal Circuit's August 27, 2013 decision in Applied Medical Resources Corp. v. Tyco Healthcare Group LP (Case No. 2012-1412) (nonprecedential) relied on the seldom-used "difference in kind" test in analyzing infringement under the doctrine of equivalents, considering whether an accused product was different in kind - rather than just degree - from the claimed invention. The concept of "difference in kind" is not new, but is cited infrequently, and usually only in passing. It was introduced as a refinement to the better known claim vitiation test, which allows courts to find non-infringement as a matter of law if a theory of equivalence would "vitiate" a claim element. Applied Medical shows that the difference-in-kind test can be an important supplement to claim vitiation analysis, particularly in cases where clear-cut distinctions can be drawn between the claimed invention and the accused device.

In Applied Medical, Applied had appealed from the district court's grant of summary judgment that Tyco's surgical trocar tools did not infringe Applied's patent literally or under the doctrine of equivalents. A trocar is a device which provides an access port through which thin instruments may be inserted into a patient's body during laparoscopic surgery. Applied's patent claimed a trocar with an "instrument seal assembly" capable of sliding side to side within the trocar like a hockey puck, allowing the surgeon to move instruments laterally in the trocar. The patent claims specifically required "free lateral movement" of the entire instrument seal assembly, as opposed to just the opening through which instruments are passed. Tyco's accused devices, by contrast, used a gimbaled instrument seal assembly which, instead of sliding side to side, pivoted about a fixed point, allowing the surgeon to angle the instruments as desired. Thus, although Tyco's instrument opening moved from side to side, the assembly itself did not.

The Federal Circuit agreed that the doctrine of claim vitiation precluded a finding of infringement under the doctrine of equivalents. The Court did not stop there, however. Noting that the district court's analysis had been only "brief," Judges Prost, Schall and Reyna applied the difference-in-kind test, explaining that "[o]ur case law indicates that a finding of infringement under the doctrine of equivalents vitiates a claim limitation when the aspect of the accused device that allegedly meets that limitation represents a...