Depuy Spine, Inc. v. Biedermann Motech GMBH, No. 2008-1240, -1253, -1401 (Fed. Cir. June 1, 2009):
1. “Ensnarement, like prosecution history estoppel, is a legal limitation on the doctrine of equivalents to be decided by the court, not a jury.” Slip op. at 7.
2. The first Panduit factor simply asks whether demand existed for the patented product and the focus on particular features corresponding to individual claim limitations is unnecessary. Id. at 21, 23.
3. “In contrast to such functionally-integrated components that are properly subject to lost profits, ‘there is no basis for extending that recovery to include damages for [unpatented] items that are neither competitive with nor function with the patented invention.’” Id. at 27.
4. “The reverse doctrine of equivalents, like the doctrine of equivalents, is applied to individual limitations of a claim.” Thus, the fact that a party argued on claim limitation under a doctrine of equivalents theory of infringement does not prevent the other party from raising the reverse doctrine of equivalents against the literal scope of a different limitation. Id. at 38.
“Ensnarement bars a patentee from asserting a scope of equivalency that would encompass, or ‘ensnare,’ the prior art.” Id. at 6.
“A helpful first step in an ensnarement analysis is to construct a hypothetical claim that literally covers the accused device.” Id. at 11.
“Next, the district court must assess the prior art introduced by the accused infringer and determine whether the patentee has carried its burden of persuading the court that the hypothetical claim is patentable over the prior art.” Id.
[T]he four-factor Panduit test . . . requires a showing of (1) demand for the patented product, (2) absence of acceptable noninfringing substitutes, (3) manufacturing and marketing capability to exploit the demand, and (4) the amount of profit that would have been made.
Id. at 20 (citing Panduit Corp. v. Stahlin Bros. Fibre Works, Inc., 575 F.2d 1152, 1156 (6th Cir. 1978)).
[W]here a device is so far changed in principle from a patented article that it performs the same or similar function in a substantially different way, but nevertheless falls within the literal words of the claim, the [reverse] doctrine of equivalents may be used to restrict the claim and defeat the patentee’s action for infringement.
Id. at 37 (citing Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 608-09 (1950)).