Depuy Spine v. Medtronic (CAFC 2008-1240, -1253, 1401) precedential

On remand, Medtronic raised an "ensnarement" defense against the doctrine of equivalents, arguing that the asserted scope of equivalency would encompass, or "ensnare," the prior art. Specifically, Medtronic argued that the combination of U.S. Patent No. 5,474,555 ("Puno") and U.S. Patent No. 2,346,346 ("Anderson") would have rendered obvious a "hypothetical" version of claim 1 of the '678 patent, in which the phrase "conically-shaped" is substituted for the actual claim term "spherically-shaped." The district court took the question from the jury and held that ensnarement, like prosecution history estoppel, is a legal limitation on the doctrine of equivalents that would be decided by the court at the conclusion of the infringement proceeding. Depuy Spine, Inc. v. Medtronic Sofamor Danek, Inc., 515 F. Supp. 2d 206 (D. Mass. 2007).

After the jury trial, the district court conducted a separate bench trial on Medtronic's ensnarement defense. In a memorandum and order dated December 11, 2007, the district court held that the combination of Puno and Anderson did not render the hypothetical claim obvious. Ensnarement Order, 526 F. Supp. 2d at 176.

In a concurrent reexam, the PTO agreed, "that all (actual) claims under reexamination were being confirmed over Puno and Anderson without change."

Ensnarement bars a patentee from asserting a scope of equivalency that would encompass, or "ensnare," the prior art. See Wilson Sporting Goods Co. v. David Geoffrey & Assoc., 904 F.2d 677, 683 (Fed. Cir. 1990), overruled in part on other grounds, Cardinal Chem. Co. v. Morton Int'l, Inc., 508 U.S. 83, 92 n.12 (1993).

The interesting question is whether, as a prior art analysis, ensnarement is a matter of fact to be put before a jury, or, as the district court judge decided, a matter of law. No surprise of controlling interest here, with lip service to juries.

"The constitutional question of whether a party is entitled to a jury trial is a question of law that this court reviews de novo." Tegal Corp. v. Tokyo Electron Am., Inc., 257 F.3d 1331, 1339 (Fed. Cir. 2001). Medtronic argues that ensnarement, like infringement, must be tried to a jury when requested by a defendant. Although Medtronic acknowledges that ensnarement is ultimately a question of law, see Wilson Sporting Goods, 904 F.2d at 683, Medtronic argues that ensnarement's underlying factual issues must be resolved by a jury if one is requested.

Notwithstanding the jury's proper fact-finding role in assessing the equivalence of each limitation of a claim, the Supreme Court has recognized "various legal limitations on the application of the doctrine of equivalents." Warner-Jenkinson Co., Inc. v. Hilton Davis Chem. Co., 520 U.S. 17, 39 n.8 (1997). These "legal limitations . . . are to be determined by the court either on a pretrial motion for partial summary judgment or on a motion for judgment as a matter of law at the close of the evidence and after the jury verdict." Id. (emphasis added). In Warner-Jenkinson, the Supreme Court identified two such "legal limitations": (1) the "all-elements rule," which bars a patentee from asserting "a theory of equivalence [that] would entirely vitiate a particular claim element," and (2) prosecution history estoppel, which bars a patentee from asserting a scope of equivalency surrendered during prosecution. Id. On the issue of prosecution history estoppel, our second en banc Festo decision held that "the determinations concerning whether the presumption of surrender has arisen and whether it has been rebutted are questions of law for the court, not a jury, to decide." Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd., 344 F.3d 1359, 1368 (Fed. Cir. 2003) (en banc) (emphasis added).

Although Warner-Jenkinson did not explicitly mention "ensnarement" as one of the "various legal limitations on the application of the doctrine of equivalents" to be decided by a court, we have consistently treated it as such. We have called ensnarement and prosecution history estoppel, collectively, "two policy oriented limitations" on the doctrine of equivalents, both of which are "applied as questions of law." Loctite Corp. v. Ultraseal Ltd., 781 F.2d 861, 870 (Fed. Cir. 1985), overruled in part on other grounds, Nobelpharma AB v. Implant Innovations, Inc., 141 F.3d 1059, 1068 (Fed. Cir. 1998) (en banc). Ensnarement, like prosecution history estoppel, limits the scope of equivalency that a patentee is allowed to assert. This limitation is imposed even if a jury has found equivalence as to each claim element. See Wilson Sporting Goods, 904 F.2d at 683 ("Even if this [function-way-result] test is met, however, there can be no infringement if the asserted scope of equivalency of what is literally claimed would encompass the prior art."); id. at 687 (deciding ensnarement "as a matter of law" after jury found infringement). The ensnarement inquiry is separate and distinct from the jury's element-by-element equivalence analysis, and it has no bearing on the validity of the actual claims. See id. at 685 ("Wilson's claims will remain valid whether or not Wilson persuades us that it is entitled to the range of equivalents sought here.").

We see no reason why ensnarement should be treated differently, for procedural purposes, than prosecution history estoppel. As mentioned, both are "legal limitation[s] on the application of the doctrine of equivalents," decided as questions of law, and reviewed de novo. Festo, 344 F.3d at 1368; Wilson Sporting Goods, 904 F.2d at 683. In both analyses, the burden of persuasion is on the patentee to establish either that the reason for the amendment was unrelated to patentability, Warner-Jenkinson, 520 U.S at 33 (prosecution history estoppel), or that the asserted scope of equivalency would not ensnare the prior art, Wilson Sporting Goods, 904 F.2d at 685 (ensnarement). Although both analyses "may be subject to underlying facts," we have recognized that "the resolution of factual issues underlying a legal question may properly be decided by the court," Festo, 344 F.3d at 1368 n.3 (prosecution history estoppel), and we review the district court's resolution of those factual issues for clear error, Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd., 493 F.3d 1368, 1376 (Fed. Cir. 2007) (prosecution history estoppel). Accordingly, we hold that ensnarement, like prosecution history estoppel, is "to be determined by the court, either on a pretrial motion for partial summary judgment or on a motion for judgment as a matter of law at the close of the evidence and after the jury verdict." Warner-Jenkinson, 520 U.S at 39 n.8. As a practical matter, both legal limitations may be readily addressed in the same set of motions.

For guidance on resolving ensnarement's factual issues, we again draw analogy to prosecution history estoppel, particularly in the context of rebutting the presumption of surrender under the "foreseeability" criterion. See Festo, 344 F.3d at 1369 ("This criterion presents an objective inquiry, asking whether the alleged equivalent would have been unforeseeable to one of ordinary skill in the art at the time of the amendment."). In that context, when deciding whether an equivalent would have been unforeseeable, "a district court may hear expert testimony and consider other extrinsic evidence relating to the relevant factual inquiries," including "the state of the art and the understanding of a hypothetical person of ordinary skill in the art at the time of the amendment." Id. So too, in the ensnarement context, a district court may hear expert testimony and consider other extrinsic evidence regarding: (1) the scope and content of the prior art; (2) the differences between the prior art and the claimed invention; (3) the level of ordinary skill in the art; and (4) any relevant secondary considerations. Graham v. John Deere Co., 383 U.S. 1, 17-18 (1966). If a district court believes that an advisory verdict would be helpful, and that a "hypothetical claim" construct would not unduly confuse the jury as to equivalence and validity, then one may be obtained under Federal Rule of Civil Procedure 39(c). See, e.g., Interactive Pictures Corp. v. Infinite Pictures, Inc., 274 F.3d 1371, 1375 (Fed. Cir. 2001) (ensnarement submitted to jury with parties' consent). Ultimately, however, ensnarement is a question of law for the court, not the jury, to decide.

The CAFC then went through the process in the instant dispute.

A helpful first step in an ensnarement analysis is to construct a hypothetical claim that literally covers the accused device. Interactive Pictures, 274 F.3d at 1380.

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. Interactive Pictures, 274 F.3d at 1380. Ultimately, "[i]f such a claim would be unpatentable under 35 U.S.C. §§ 102 or 103, then the patentee has overreached, and the accused device is noninfringing as a matter of law." Id.

DePuy argued that the prior art taught away from combination as asserted by Medtronic.

Although predictability is a touchstone of obviousness, the "predictable result" discussed in KSR refers not only to the expectation that prior art elements are capable of being physically combined, but also that the combination would have worked for its intended purpose. KSR Int'l Co. v. Teleflex Inc., 127 S. Ct. 1727, 1739-40 (2007). As the Supreme Court explained, "The combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results." Id. at 1739 (emphasis added). The Supreme Court went on to state that "when a patent 'simply arranges old elements with each performing the same function it had been known to perform' and yields no more than one would expect from such an arrangement, the combination is obvious." Id. at 1740 (quoting Sakraida v. Ag Pro, Inc., 425 U.S. 273, 282 (1976)) (emphasis added). The opposite conclusion would follow, however, if the prior art indicated that the invention would not have worked for its intended purpose or otherwise taught away from the invention. See United States v. Adams, 383 U.S. 39, 52 (1966) (upholding nonobviousness where references teaching away from the claimed combination would "deter any investigation into such a combination"); In re ICON Health & Fitness, Inc., 496 F.3d 1374, 1382 (Fed. Cir. 2007) ("[A] reference teaches away from a combination when using it in that combination would produce an inoperative result."). An inference of nonobviousness is especially strong where the prior art's teachings undermine the very reason being proffered as to why a person of ordinary skill would have combined the known elements.

"A reference may be said to teach away when a person of ordinary skill, upon reading the reference, would be discouraged from following the path set out in the reference, or would be led in a direction divergent from the path that was taken by the applicant." Ricoh Co., Ltd. v. Quanta Computer Inc., 550 F.3d 1325, 1332 (Fed. Cir. 2008) (quoting In re Kahn, 441 F.3d 977, 990 (Fed. Cir. 2006)). A reference does not teach away, however, if it merely expresses a general preference for an alternative invention but does not "criticize, discredit, or otherwise discourage" investigation into the invention claimed. In re Fulton, 391 F.3d 1195, 1201 (Fed. Cir. 2004).

The CAFC affirmed the district court finding that the prior art reference by Puno taught away from the claimed invention, which employed a rigid screw.

Puno's specification taught away from a rigid screw.

Issues in the case relating to damages using lost profits, willfulness, and defense using the reverse doctrine of equivalents are handled in succeeding entries.