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April 18, 2008


Honeywell sued Hamilton Sundstrand over 4,380,893 and 4,428,194. One of asserted claims had been an unamended dependent rewritten into independent form, triggering presumption of prosecution estoppel, though why that should be is the locus of dispute. In a previous CAFC appearance, infringement from doctrine of equivalents (DOE) had been vacated, with the district court to examine whether the Festo presumption could be rebutted. This episode, a 2-1 panel majority oversteps applying DOE.

Honeywell v. Hamilton Sundstrand (CAFC 06-1602)

Judge Rader penned the opinion, joined by DYK.

Under the doctrine of the equivalents, "a product or process that does not literally infringe upon the express terms of a patent claim may nonetheless be found to infringe if there is 'equivalence' between the elements of the accused product or process and the claimed elements of the patented invention." Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 21 (1997) (citing Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 609 (1950)). The doctrine of prosecution history estoppel prevents a patent owner from recapturing with the doctrine of equivalents subject matter surrendered to acquire the patent. See Festo IX, 344 F.3d at 1365 (citing Festo VIII, 535 U.S. at 741).

Because "rewriting of dependent claims into independent form coupled with the cancellation of the original independent claims creates a presumption of prosecution history estoppel," this court vacated an earlier infringement verdict in favor of Honeywell and remanded to determine whether Honeywell could rebut the presumption of surrender under Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co, 535 U.S. 722 (2002) (Festo VIII), remanded to 344 F.3d 1359 (Fed. Cir. 2003) (en banc) (Festo IX). Honeywell Int'l Inc. v. Hamilton Sundstrand Corp., 370 F.3d 1131, 1134 (Fed. Cir. 2004) (en banc) (Honeywell II). On remand, the United States District Court for the District of Delaware barred Honeywell from asserting the doctrine of equivalents. Honeywell Int'l Inc. v. Hamilton Sundstrand Corp., No. 99-309, 2006 U.S. Dist. LEXIS 57030, at *2 (D. Del. Aug. 14, 2006) (Honeywell III).

The district court correctly stated that Honeywell could rebut the presumption of surrender by demonstrating that (1) "the alleged equivalent would have been unforeseeable at the time of the narrowing amendment," or (2) "the rationale underlying the narrowing amendment bore no more than a tangential relation to the equivalent in question," or (3) "that there was 'some other reason' suggesting that the patentee could not reasonably have been expected to have described the alleged equivalent." Id. at *14 (quoting Festo IX, 344 F.3d at 1369).

Honeywell conceded the "some other reason" criterion. Honeywell Int'l Inc. v. Hamilton Sundstrand Corp., No 99-309, 2006 WL 2346446 (D. Del. Aug. 14, 2006). Thus, the district court focused on tangentiality and foreseeability.

Because Honeywell did not show that the alleged equivalent was unforeseeable at the time of the narrowing amendment or that the narrowing amendment bore no more than a tangential relation to the alleged equivalent, this court affirms.

A. Foreseeability

On remand from the Supreme Court in Festo, this court explained that the foreseeability 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. Usually, if the alleged equivalent represents later-developed technology (e.g., transistors in relation to vacuum tubes, or Velcro (R) in relation to fasteners) or technology that was not known in the relevant art, then it would not have been foreseeable. In contrast, old technology, while not always foreseeable, would more likely have been foreseeable. Indeed, if the alleged equivalent were known in the prior art in the field of the invention, it certainly should have been foreseeable at the time of the amendment. By its very nature, objective unforeseeability depends on underlying factual issues relating to, for example, the state of the art and the understanding of a hypothetical person of ordinary skill in the art at the time of the amendment. Therefore, in determining whether an alleged equivalent would have been unforeseeable, a district court may hear expert testimony and consider other extrinsic evidence relating to the relevant factual inquiries.

Id. at 1369 (citation omitted). Subsequently, we clarified that "[a]n equivalent is foreseeable if one skilled in the art would have known that the alternative existed in the field of art as defined by the original claim scope, even if the suitability of the alternative for the particular purposes defined by the amended claim scope were unknown." Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 493 F.3d 1368, 1382 (Fed. Cir. 2007) (Festo X).

The principle of foreseeability ties patent enforcement appropriately to patent acquisition. In making this connection, foreseeability reconciles the preeminent notice function of patent claims with the protective function of the doctrine of equivalents. Thus, foreseeability in this context ensures that the doctrine does not capture subject matter that the patent drafter could have foreseen during prosecution and included in the claims. The goal of the principle is to ensure that the claims continue to define patent scope in all foreseeable circumstances, while protecting patent owners against insubstantial variations from a claimed element in unforeseeable circumstances. The foreseeability principle thus relegates the doctrine of equivalents to its appropriate exceptional place in patent enforcement.

To maintain consistency, a court must use the same definition of the equivalent to evaluate both foreseeability and infringement. As we explained in Festo X, adoption of different equivalents for infringement and foreseeability would produce perverse results. Id. at 1381. Under such a paradigm, patentees and accused infringers would reverse roles when arguing whether the equivalent met the test for infringement on the one hand, and foreseeability, on the other. Id. In this instance, the district court found that even the narrow equivalent proposed by Honeywell was foreseeable and thus precluded by estoppel principles. We agree.

B. Tangential Relation

The tangential relation criterion for overcoming the Festo presumption is very narrow. Cross Med. Prods., Inc. v. Medtronic Sofamor Danek, Inc., 480 F.3d 1335, 1342 (Fed. Cir. 2007). As this court provided in its Festo IX opinion on remand from the Supreme Court, the tangential relation criterion focuses on the "patentee's objectively apparent reason for the narrowing amendment." 344 F.3d at 1369. To rebut the estoppel presumption with tangentiality, a patentee must "demonstrate that the rationale underlying the amendment bore no more than a tangential relation to the equivalent in question," or, in other words, that "the narrowing amendment was peripheral, or not directly relevant, to the alleged equivalent." Id. (citation omitted). Additionally, the reason for the narrowing amendment "should be discernible from the prosecution history record . . . ." Id. If the prosecution history reveals no reason for the narrowing amendment, the presumption is not rebutted. See id. at 1371-72 (the patentee did not rebut because the prosecution history revealed no reason for the amendment). Silence does not overcome the presumption.

The record shows that the examiner simply instructed that the dependent claims would be allowed if rewritten into independent form. Those instructions, however, must be placed in their proper context. As this court explained in Festo IX, "whether an amendment was merely tangential to an alleged equivalent necessarily requires focus on the context in which the amendment was made . . . ." 344 F.3d at 1370.

The sharpest tack in the box, Judge Newman dissented, pointing out the flawed logic, that, under the current CAFC guidelines, presumptive surrender has "no outer limit." To Newman, an unamended claim, including a dependent, surrenders nothing.

The court today applies its new presumption of surrender to all equivalents of the claim elements and limitations that originated in dependent claims that were never amended and that were not the subject of prosecution history estoppel. The court held in its previous opinion, Honeywell Int'l, Inc. v. Hamilton Sundstrand Corp., 370 F.3d 1131 (Fed. Cir. 2004) that "the surrendered subject matter is defined by the cancellation of independent claims that do not include a particular limitation and the rewriting into independent form of dependent claims that do include that limitation." Id. at 1144. Thus, although the limitation at issue (the inlet guide vanes used to control surge) had not been the subject of amendment, argument, or any other form of restriction, the court held that all equivalent guide vanes were presumed surrendered, not simply equivalents presumptively barred by prosecution history estoppel. Id. My colleagues held that since there was no narrowing amendment or limiting argument during prosecution of the Honeywell dependent claims, surrender of the entire universe of potential equivalents is presumed when the original independent claim is cancelled. I have previously pointed out the flaws in these generalizations, id. at 1146 (Newman, J., dissenting in part), for neither precedent nor logic requires the presumption of unlimited surrender when the prosecution history does not support unlimited surrender. See Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S.722 (2002):

The complete bar [] is inconsistent with the purpose of applying the estoppel in the first place -- to hold the inventor to the representations made during the application process and to the inferences that may reasonably be drawn from the amendment. By amending the application, the inventor is deemed to concede that the patent does not extend as far as the original claim. It does not follow, however, that the amended claim becomes so perfect in its description that no one could devise an equivalent. After amendment, as before, language remains an imperfect fit for invention. The narrowing amendment may demonstrate what the claim is not; but it may still fail to capture precisely what the claim is.

This court, after creating its new presumption of surrender, did not apply it to the Honeywell-Sundstrand issues on appeal, instead remanding to the district court. Indeed, the district court remarked on the absence of guidance, stating that it was "entering uncharted waters" in which it must "knock the rust off the old sextant and hope for the best." Honeywell Int'l Inc. v. Hamilton Sundstrand Corp., No. 99-309, 2006 WL 2346446 , at *6 n.3 (D. Del. Aug. 14, 2006). Now my colleagues, apparently unsatisfied with the district court's analysis, offer their own, presenting a new rationale whereby they find that Honeywell engineers were indeed capable of solving the Sundstrand "double solution" problem using inlet guide vanes, although Honeywell did not do so, and therefore that the Sundstrand equivalent was "foreseeable" to Honeywell and should have been patented by Honeywell in 1983. On this theory, my colleagues hold that this equivalent (as the jury found) cannot be reached under the doctrine of equivalents. The flawed sweep of this new rule is illustrated as my colleagues apply the rebuttal criteria of "foreseeability" and "tangentialness" to a presumptive surrender with no outer limit, for there is no prosecution history that narrowed the claim element at issue.

My colleagues not only broaden the grounds of presumptive estoppel to estop all equivalents to any of the elements and limitations that were presented in the dependent claims, but they also restrict the grounds of rebuttal by holding that "foreseeability" is established by other than the "readily known equivalents" contemplated by the Court in Festo, 535 U.S. at 740.

Rebuttal of the presumption of surrender -- foreseeability

[M]y colleagues apply the Festo rebuttal criteria in significantly more restrictive ways than were established by the Supreme Court. The Court had explained that "[t]hough prosecution history estoppel can bar a patentee from challenging a wide range of alleged equivalents made or distributed by competitors, its reach requires an examination of the subject matter surrendered by the narrowing amendment." Id. at 737. However, my colleagues do not examine the surrendered subject matter, and indeed they can not, for there is no narrowing amendment to define surrendered subject matter. The dependent claims were not rejected on any ground; they were simply "objected to" because they were in dependent form. There was no prosecution for this issue based on prior art. Unlike the Court's Festo presumption of prosecution history estoppel, which is limited by narrowing amendment, the panel majority's presumption of surrender is without limit. Honeywell, 370 F.3d at 1144 ("Under such circumstances, the surrendered subject matter is defined by the cancellation of independent claims that do not include a particular limitation and the rewriting into independent form of dependent claims that do include that limitation. Equivalents are presumptively not available with respect to that added limitation.").

Equivalency is determined as of the time of litigation, while foreseeability for equivalency purposes is determined at the time of the patent application. The Court in Festo explained that foreseeability means "readily known equivalents," 535 U.S. at 740, not unknown equivalents developed a decade later.

In deciding whether the presumption of surrender has been rebutted, the question is whether the technological equivalent is embraced by subject matter that was relinquished during prosecution of the patent. This requires analysis of the prosecution history leading to cancellation of the original independent claim and rewriting of the original dependent claim in independent form. Patent claims are customarily presented in independent and dependent form, a practice encouraged by the Patent and Trademark Office, for it simplifies examination. When an original independent claim is cancelled, it is obligatory that the next dependent claim be placed in independent form. Even on the majority's analysis of the rebuttal criteria of foreseeability and tangentialness, the proper approach is to determine what prompted the cancellation of the independent claim, and whether the element at issue for equivalency was implicated in that cancellation.

Simply presenting claims of varying scope, whether in independent or dependent form, is not a narrowing amendment or argument. The patent examining rules encourage, through lowered fees, the use of dependent claims, for it facilitates examination. It is routine for broader claims to be cancelled and dependent claims to be rewritten in independent form. This protocol has no relevance to whether a claimed element is amended or narrowed or argued during prosecution. It is the narrowing of scope during prosecution that produces the presumptive estoppel; claim elements and limitations that were not the subject of amendment or argument do not raise the Festo presumption, and should not be deemed to raise this court's new presumption. Cancelling an independent claim is not an estoppel-generating act as to elements whose scope was not amended or otherwise restricted during prosecution.

Equivalency is determined element by element, Warner-Jenkinson, 520 U.S. at 29, yet on the panel majority's presumption of surrender, there is no restricting action by which to measure what was surrendered. In Festo the Court was explicit that the burden is to "show[] that the amendment does not surrender the particular equivalent in question." 535 U.S. at 740. My colleagues err in now holding that all equivalents of an element presented by dependent claim are presumed surrendered by simply cancelling the independent claim.

Tangential Relation

The Court explained that when the asserted equivalent related to "aspects of the invention that have only a peripheral relation to the reason the amendment was submitted," the presumption of estoppel would be rebutted. Id. at 738. Precedent illustrates that the "tangential" criterion is rebutted when "[t]here is no indication in the prosecution history of any relationship between the narrowing amendment and [the process] which is the alleged equivalent in this case." Insituform Tech., Inc. v. Cat Contracting, Inc., 385 F.3d 1360, 1370 (Fed. Cir. 2004). That analysis well fits this case, for there is no indication in the prosecution history of any relationship between Honeywell's cancellation of the independent claim and the alleged equivalent Sundstrand apparatus or method.

It does not suffice to say that by narrowing a claim by adding an element, ipso facto the relation to the accused equivalent element is not tangential. This criterion relates to why an amendment was made; it does not become irrebuttable simply when the accused equivalent concerns the same element that was added by amendment.

Exploration of this criterion requires, at a minimum, review of the reason for cancellation of the independent claim and rewriting the dependent claim in independent form. The panel majority makes no mention of the prosecution of the original independent claims, except to state that the examiner rejected them on the ground of obviousness. Although the panel majority states that "the key to this inquiry is the content of the original dependent claims," this obscure statement leads to no analysis. In a situation where an originally dependent claim is asserted against an infringer under the doctrine of equivalents, and the asserted limitation was first introduced in a dependent claim, then according to the panel majority there is always more than a tangential relationship between the reason for the amendment and the accused equivalent, even when there is no finding as to the reason for the amendment. This renders the presumption of estoppel irrebuttable, whatever the reason for the amendment. However, the question is whether the subject matter of the accused equivalent was relinquished by the patentee during prosecution. This question should be resolved on its facts, not converted into a complete bar.

Why does it matter?

The court's holding today takes another step to remove patent issues from the jury, but adds nothing to consistency or stability or predictability of the law. I respectfully dissent.

Posted by Patent Hawk at April 18, 2008 1:04 PM | Claim Construction


Well, Randall, you just buried the DOE forever. Hint: when Pauline disagrees with you, take notice, because she's probably right.

Posted by: Federally Circuitous at April 20, 2008 11:15 AM