Full opinion text
MEMORANDUM AND ORDER YOUNG, Chief Judge. INTRODUCTORY NOTE: On September 18, 2003, this Court held that Amgen had successfully rebutted the presumption of prosecution history es-toppel but noted that it might have to revisit the issue if the Federal Circuit’s Festo opinion was published before this Court’s opinion was finished. 9/18/03 Pretrial Conference Tr. at 7, 11. 17-25, and 8,11. 1-5. This Court had scheduled release of this opinion for early October, 2003, pending final proofreading. The Federal Circuit released its opinion in Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd., 344 F.3d 1359 (Fed.Cir.2003) {“Festo III”) on September 26, 2003. Becausé Festo III authoritatively interprets the Supreme Court’s decision in Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd., 535 U.S. 722, 122 S.Ct. 1831, 152 L.Ed.2d 944 (2002) (“Festo II ”), the recent Federal Circuit decision governs here under familiar stare deci-sis principles. As this Court’s interpretation of the Supreme Court decision had proceeded along a somewhat different tack, and since the growth of the law in this area “moves at a lightning pace,” Festo III, 344 F.3d at 1375-76 (Rader, J., concurring), it seems appropriate to set forth this Court’s original analysis of Festo II, noting its confirmation or remediation on a section-by-section basis by the Federal Circuit in Festo III, and identifying and setting forth the revised analysis required by that decision. As will be discussed in further detail below, this Court reasserts its prior holding — in light of Festo III — that Am-gen has successfully rebutted the presumption of prosecution history estop-pel. Therefore, its earlier finding that HMR/TKT infringes claims 2 through 4 of U.S. Patent No. 5,621,080 (issued April 15, 1997) (the “ ’080 patent”) is reaffirmed. I. INTRODUCTION In light of the recent Supreme Court decision in Festo II, 535 U.S. 722,122 S.Ct. 1831, 152 L.Ed.2d 944, the Federal Circuit remanded to this Court its ruling in Amgen, Inc. v. Hoechst Manon Roussel, Inc., 126 F.Supp.2d 69 (D.Mass.2001) (“Amgen I”), that Amgen, Inc. (“Amgen”) was not estopped by the prosecution history from claiming equivalent infringement by the human erythropoietin (“EPO”) product (“HMR 4396”) produced by Hoechst Marion Roussel, Inc. and Transkaryotie Therapies, Inc. (collectively “HMR/TKT”). Amgen Inc. v. Hoechst Manon Roussel, Inc., 314 F.3d 1313, 1345 (Fed.Cir.2003) (“Amgen II ”). Based upon Festo II, the Federal Circuit ruled that a presumption of prosecution history estoppel applied here. Therefore, it vacated this Court’s finding of equivalent infringement and remanded “for an analysis under the narrow ways of rebutting the Supreme Court’s presumption of estoppel” as laid out in Festo II. Amgen II, 314 F.3d at 1345. This opinion addresses the discrete issue of whether Amgen has successfully rebutted the Festo II presumption of prosecution history estoppel held to be present in Amgen II. Id. II. DISCUSSION A. Background and Procedural History In Amgen I, this Court construed the amendment “mature erythropoietin amino acid sequence of FIG. 6” in claims 2-4 of U.S. Patent No. 5,621,080 (issued April 15, 1997) (the “’080 patent”) as requiring an EPO glycoprotein “comprising the fully realized erythropoietin amino acid sequence of Figure 6, which depicts 166 amino acids.” Amgen I, 126 F.Supp.2d at 100. Pursuant to this construction, the Court found that HMR 4396 did not literally infringe claims 2, 3, and 4 of the ’080 patent because HMR 4396 comprised only 165 amino acids. Id. at 101. This Court then turned to the doctrine of equivalents and found that HMR 4396 performed substantially the same function in substantially the same way to obtain substantially the same result as the EPO glycoprotein of claims 2 and 3 of the ’080 patent. Id. at 133. Therefore, it ruled that Amgen’s ’080 patent was equivalently infringed by TKT/HMR’s product. Id. In response to TKT/HMR’s argument that Amgen should be estopped from arguing equivalent infringement, this Court ruled that prosecution history estoppel did not apply because Amgen did not add the “mature amino acid sequence of Figure 6” limitation “in an attempt to overcome a rejection, to avoid prior art,” but, instead, to “demonstrate that ‘same invention’ type double patenting did not apply,” that is, to distinguish the ’080 patent from U.S. Patent No. 5,547,933 (the “ ’933 patent”). Id. at 134-35. The Federal Circuit agreed that the amendment was made for this purpose but made clear that under Festo II, “a narrowing amendment to satisfy any requirement of the Patent Act may give rise to an estoppel.” Amgen II, 314 F.3d at 1345 (emphasis added). Therefore, it held that the presumption of prosecution history es-toppel applied here. The Federal Circuit then vacated this Court’s finding of equivalent infringement and remanded for an analysis based on the “narrow ways of rebutting the Supreme Court’s presumption of estoppel” outlined in Festo II. Id. at 1345. Because the Court’s factual findings (that TKT/HMR’s product performed substantially the same function in substantially the same way to obtain substantially the same result) were not disturbed—or even challenged—on appeal, the Court need only analyze whether Amgen can rebut the presumption of prosecution history estop-pel and pursue an infringement claim based on the doctrine of equivalents. If Amgen can, the Court’s ruling that Am-gen’s ’080 patent was equivalently infringed shall be reaffirmed. On May 16, 2003, Amgen moved for judgment under the Federal Rule of Civil Procedure 52(c) that claims 2-4 of the ’080 patent are equivalently infringed [Document No. 659]. TKT/HMR opposed Am-gen’s motion and moved for judgment that Amgen is estopped from asserting infringement under the doctrine of equivalents [Document No. 678]. Both parties, however, have agreed that the Court summarily can decide this motion based on the current record without further evidentiary presentation. TKT/HMR’s Mem. in Opp’n at 1; Amgen’s Mem. in Support at 5-6. B. Overview Of Festo II As Interpreted By This Court And The Federal Circuit The doctrine of equivalents was created because language is not always sufficiently precise to capture the essence, nuances, and range of an invention in light of unexpected technological advances. Festo II, 535 U.S. at 731, 122 S.Ct. 1831 (“Things are not made for the sake of words, but words for things.” (quoting Autogiro Co. of America v. United States, 181 Ct.Cl. 55, 384 F.2d 391, 397 (1967))). The doctrine of equivalents was designed to provide patent applicants the wiggle room that claim language alone cannot, thus protecting paten-tees from copyists who make insubstantial changes. Festo II, 535 U.S. at 732-33, 122 S.Ct. 1831; Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 607, 70 S.Ct. 854, 94 L.Ed. 1097 (1950). In other words, it was designed to protect the intended invention, even if not adequately or ably described. Prosecution history estoppel, on the other hand, arises when an amendment, by its language, discernibly limits the scope of the invention before the Patent and Trademark Office (the “Patent Office”). The purpose of prosecution history estoppel is to “hold the inventor to the representations made during the application process and the inferences that may reasonably be drawn from the amendment.” Festo II, 535 U.S. at 737-39, 122 S.Ct. 1831. The doctrine of equivalents is premised on language’s inability to capture the essence of innovation, but a prior application describing the precise element at issue undercuts that premise. In that instance, the prosecution history has established that the inventor turned his attention to the subject matter in question, knew the words for both the broader and narrower claim, and affirmatively chose the latter. Id. at 734-35, 122 S.Ct. 1831. Prosecution history estoppel, therefore, takes root in the virtues of public notice and the reduction of uncertainty that is sometimes created by the doctrine of equivalents. Tony Caliendo, Foreseeable Trouble: How Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co. Offends Fundamental Policies of the U.S. Patent System by Making Prosecution History Estoppel Depend Upon Foreseeability, 2003 BYU L.Rev. 309, 314 (2003). Competitors “rely on [prosecution history] estoppel to ensure that their own devices will not be found to infringe by equivalence.” Festo II, 535 U.S. at 727, 122 S.Ct. 1831. An obvious tension exists between the doctrine of equivalents and prosecution history estoppel. The doctrine of equivalents provides protection for more than just the literal claims, but this added protection creates uncertainty. Caliendo, supra, at 314. In other words, competitors are not provided notice of the breadth of the patent. Prosecution history estoppel, on the other hand, can provide such certainty and notice. The Supreme Court in Festo II tried to balance the competing interests of public notice and protection of patents by rejecting the Federal Circuit’s complete bar approach and further defining which amendments give rise to a presumption of estoppel, what equivalents are subsequently barred by such estoppel, and how the “presumption” of estoppel can be overcome. Festo II, 535 U.S. at 736-42, 122 S.Ct. 1831. 1. How Does The “Presumption” Work? a. The Court’s Original Analysis: The “presumption” of estoppel is not really a presumption at all, but rather a burden-shifting device similar to the “presumption” of patent validity. The Supreme Court in Festo II made clear that a “presumption” of prosecution history estoppel arises when an amendment is made to secure the patent and the amendment narrows its scope. Festo II, 535 U.S. at 736, 122 S.Ct. 1831. The “presumption,” however, does not completely bar the inventor from asserting infringement against any equivalents to the narrowed element. Id. at 738-39, 122 S.Ct. 1831. The inventor can overcome the “presumption” by showing that the amendment does not surrender the particular equivalent in question. Id. at 740, 122 S.Ct. 1831. Thus, this “presumption” shifts to the inventor not only the burden of production but also the burden of persuasion to get out from under the “presumption” of prosecution history estoppel outlined in Festo II. Once the patentee meets these burdens, prosecution history estoppel no longer applies and the paten-tee may allege equivalent infringement of the narrowed element. Accord Festo III, 344 F.3d at 1367-68. b. The Federal Circuit’s Analysis: CONFIRMS THIS COURT’S ANALYSIS. Neither the Federal Circuit nor the Supreme Court addressed whether the “presumption” outlined in Festo II is a true presumption. The Federal Circuit’s description of the “presumption,” however, confirms this Court’s analysis. Festo III, 344 F.3d at 1367-68. 2. What Quantum Of Evidence Is Necessary To Rebut The Presumption? a. The Court’s Original Analysis: Proof by a fair preponderance of the evidence is sufficient to rebut a “presumption” of prosecution history estoppel. While the Supreme Court made clear that the burden of overcoming the “presumption” lies with the patentee, it did not define the quantum of evidence necessary to meet such a burden. In other words, the Supreme Court did not lay out whether the patentee must make a showing by a fair preponderance of the evidence, clear and convincing evidence, or some other standard, nor has any other court yet addressed this quandary in a published opinion. Important in determining the requisite standard is the surrounding legal landscape. Here, that landscape—patent litigation concerning both the doctrine of prosecution history estoppel and the doctrine of equivalents—is riddled with uncertainty. Festo II, 535 U.S. at 732, 122 S.Ct. 1831 (“It is true that the doctrine of equivalents renders the scope of patents less certain.”). Nevertheless, the Supreme Court purposely preserved the doctrine of equivalents in Festo II; it made clear that there was value to the doctrine. Festo II, 535 U.S. at 732, 122 S.Ct. 1831 (“Each time the [Supreme] Court has considered the doctrine of equivalents, it has acknowledged this uncertainty as the price of ensuring the appropriate incentives for innovation ....”); Warner-Jenkinson, 520 U.S. at 28, 117 S.Ct. 1040 (reaffirming that the doctrine is a secure part of a paten-tee’s settled rights and stating that it was up to Congress — not the Supreme Court— to discard the doctrine). With this landscape in mind, the Court holds that the standard for overcoming the “presumption” of prosecution history estoppel is proof by a fair preponderance of the evidence for the following reasons. Instituting anything other than the most familiar standard — a fair preponderance of the evidence — would add yet another layer of uncertainty and cause litigation over prosecution history estoppel to proceed inconsistently. See John H. Strong, McCormick on Evidence § 340 (5th ed.1999) (explaining that the clear and convincing standard “has not become as standardized as is the ‘preponderance’ formula”); see also Kevin Casey, et al., Standards of Appellate Review in the Federal Circuit: Substance and Semantics, 11 Fed.Cir. B.J. 279, 323 (2001) (noting that the clear and convincing standard is “not susceptible to precise definition”). Such a result is contrary to the purpose of prosecution history estoppel and, therefore, should be avoided. Moreover, a burden of proof that is too exacting could result, de facto, in that which the Supreme Court in Festo II was trying to avoid — death of the doctrine of equivalents. Cf Note, Estopping the Madness at the PTO: Improving Patent Administration Through Prosecution History Estoppel, 116 Harv. L.Rev. 2164, 2184 (2003) (noting that the Federal Circuit could make the burden of overcoming the presumption more stringent by requiring that patentees produce clear and convincing evidence). Proof by a fair preponderance of the evidence is less exacting than proof by clear and convincing evidence, thereby enabling the “presumption” outlined in Festo II to be one that practically can be rebutted — which in turn preserves the doctrine of equivalents. See Strong, supra, at § 340 (noting that the clear and convincing standard of proof is a “more exacting measure of persuasion” than preponderance of the evidence). Furthermore, the fair preponderance of the evidence standard generally is the one that is applied in patent law. David W. Okey, Issued Patents and the Standard of Proof: Evidence Clear and Convincing or Merely Ponderous?, 17 J. Marshall J. Computer & Info. L. 557, 587 (1999). In civil litigation, the clear and convincing standard is saved for special situations in which “a particular type of claim should be disfavored on policy grounds.” Strong, supra, at § 840. Accordingly, in patent law, it is applied to challenges regarding validity because of the statutory provision found at 35 U.S.C. § 282, that a patent is “presumed” valid. Casey, supra, at 324. It is also applied when a patentee claims willful infringement of a patent, Pall Corp. v. Micron Separations, Inc., 66 F.3d 1211 (Fed.Cir.1995), or violation of the duty of disclosure. Casey, supra, at 324. While there are indeed public policy issues implicated in the doctrine of prosecution history estoppel, the “presumption” itself vindicates the public notice function of patent law. Thus, as already noted, to apply an overly exacting standard to a patentee’s ability to overcome the “presumption” would unravel the balance the Supreme Court sought between protecting the true scope of a patent and honoring a competitor’s reliance on the public record. Based on this reasoning, the Court holds that the burden of proof most appropriate for overcoming the “presumption” of prosecution history estoppel is proof by a fair preponderance of the evidence. b. The Federal Circuit’s Analysis: DID NOT ADDRESS THIS ISSUE. Neither the Federal Circuit nor the Supreme Court has discussed the quantum of evidence required to rebut the presumption. 3. What Is The Role Of The Judge And The Jury? a. The Court’s Original Analysis: Anomalous as it may seem, the jury plays no role in any of this. Although it is clear that the equitable doctrine of prosecution history estoppel is for the court to decide, see, e.g., Pioneer Magnetics, Inc. v. Micro Linear Corp., 330 F.3d 1352, 1356 (Fed.Cir.2003); CAE Screenplates Inc. v. Heinrich Fiedler GmbH & Co. KG, 224 F.3d 1308, 1319 (Fed.Cir.2000), the Supreme Court in Fes-to II did not provide guidance as to whether the determination that the patentee has rebutted the “presumption” is a question for the court or the jury. Though the bench trial in this case moots the issue here, the question generally remains. Placing these fact questions before the jury could indeed work against the goals of consistency and predictability since the Federal Circuit would be required to defer to findings of fact made at the trial court level. See Raymond G. Areaux and Theodore S. Owers, III, Festo’s Doctrine of Equivalents: Vitality Reaffirmed in View of New and Old Hurdles, 48 Loy. L.Rev. 551, 576-78 (2002). On the other hand, determining whether the presumption has been rebutted is not purely technical in nature and involves the kinds of issues— foreseeability, intent, purpose, and reasonableness—normally reserved for a jury. Cf. Arti K. Rai, Engaging Facts and Policy: A Multi-Institutional Approach to Patent System Reform, 103 Colum. L.Rev. 1035, 1096-97 (2003) (noting that “juries often decide questions of reasonableness even when facts are not in serious dispute.”). Thus, unlike the circumstances in Markman v. Westview Instruments, Inc., 517 U.S. 370, 388-90, 116 S.Ct. 1384, 134 L.Ed.2d 577 (1996), where the Court concluded, with respect to claim construction, that “history and precedent provide no clear answers,” here history and precedent do provide answers. These are matters historically resolved by American juries. For the reasons already expressed in Control Resources, however, this Court predicts that litigation over the existence of prosecution history estoppel will be taken from the jury. But see Arthur R. Miller, The Pretrial Rush to Judgment: Are the “Litigation Explosion,” “Liability Crisis,” and Efficiency Cliches Eroding Our Day in Court and Jury Trial Commitments?, 78 N.Y.U. L.Rev. 982, 1087 (2003) (criticizing the decision in Markman v. Westview Instruments, Inc., 517 U.S. 370, 116 S.Ct. 1384, 134 L.Ed.2d 577 (1996), which embodies this trend in patent law). For the larger implications of marginalizing the jury’s historic role, see William G. Young, An Open Letter to United State District Judges, Fed. Lawyer (2003). See generally Ellen E. Sward, The Decline of the Civil Jury (2003). b. The Federal Circuit’s Analysis: CONFIRMS THIS COURT’S PREDICTION BUT WITH A STRIKINGLY DIFFERENT ANALYSIS. While the Federal Circuit characterizes the rebuttal question as it relates to the foreseeability criterion as involving mixed fact-law issues, Festo III, 344 F.3d at 1368-69, it treats the issue as one for the district court (not a jury) to decide in the first instance. Id. at 1367-68. This can be interpreted to mean that determining whether the “presumption” has been rebutted should be decided by the court because it arises in the context of an equitable defense and involves nuanced questions of mixed fact and law. This is the reading of Festo III that makes the most sense. It is fully supported by the cases cited by the Federal Circuit in this portion of the Festo III decision. Id. at 1367-68 (citing Loctite Corp. v. Ultraseal Ltd., 781 F.2d 861, 871 n. 7 (Fed.Cir.1985), overruled on other grounds by Nobelpharma AB v. Implant Innovations, Inc., 141 F.3d 1059, 1068 (Fed.Cir.1998); Black & Decker, Inc. v. Hoover Serv. Ctr., 886 F.2d 1285, 1295 (Fed.Cir.1989); Builders Concrete, Inc. v. Bremerton Concrete Prods. Co., 767 F.2d 255, 258 (Fed.Cir.1985)). In other words, as the entire concept of prosecution history estoppel is a judicially created equitable doctrine, it makes prefect sense for the district court to do equity in the premises and make the necessarily nuanced fact finding subject to deferential appellate review. The analysis above comports with prior Federal Circuit decisions and, moreover, is logical and practical. Unfortunately, it appears not to be what the Federal Circuit intends — “[T]he 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 III, 344 F.3d at 1368 (emphasis added). One could hope that the Federal Circuit meant only that the factual issues were reserved for the court given their equitable antecedents and that the phrase “of law” crept in during drafting without much thought. Such comforting yearnings are dashed, however, by the incisive dissent of Judge Newman who points out: This court now denies Festo the opportunity to present evidence as to the two criteria of tangentialness and some other reason, establishing these criteria as questions of law, not fact, and decides these questions of first impression without development and without evidence. Id. at 1383 (Newman, J., concurring in part and dissenting in part). In the face of this language, it would strain credulity to conclude that the majority intended something other than pure rulings of law, reviewed de novo on appeal. 4. Did The Supreme Court Define One Over-Arching Standard Or Three Distinct Criteria For Rebutting The Presumption? a. The Court’s Original Analysis: Festo II provides one broad, overarching standard for rebutting the “presumption” of prosecution history estoppel. While Amgen and TKT/HMR agree that Amgen bears the burden of showing that the “presumption” of prosecution history estoppel is rebutted by a fair preponderance of the evidence, they disagree about what the evidence must show; that is, they interpret the Supreme Court’s decision in Festo II differently. TKT/HMR asserts that Festo II depicts a single rebuttal standard: whether “at the time of the amendment one skilled in the art could not reasonably be expected to have drafted a claim that would have literally encompassed the alleged equivalent.” TKT/ HMR’s Mem. in Support at 2 (quoting Festo II, 535 U.S. at 741, 122 S.Ct. 1831.) Amgen, on the other hand, argues that Festo II outlines three independent methods (described below) in which to rebut the “presumption” of estoppel. Amgen’s Mem. in Opp’n re: ’080 [Document No. 716] at 3, 7. Upon reflection it appears that both parties are partly correct. Amgen is correct in asserting that Festo II lays out more than one way in which to rebut the “presumption” of estoppel. See, e.g., Schwing GmbH v. Putzmeister Aktiengesellschaft, 305 F.3d 1318, 1329 (Fed.Cir.2002) (citing various methods in which to rebut and remanding to the district court); Sound-Tube Entertainment, Inc. v. Brown Innovations, Inc., 233 F.Supp.2d 188, 196-97 (D.Mass.2002) (Saris, J.) (applying the various methods of rebutting the presumption); see also Amgen II, 314 F.3d at 1345 (referring to Festo II’s “narrow ways” of rebuttal and citing the page in Festo II that sets out rebutting circumstances) (emphasis added). Indeed, in Festo II, the Supreme Court described three situations in which an amendment cannot reasonably be viewed as surrendering the equivalent in question: (1) when the equivalent was unforeseeable; (2) when the rationale underlying the amendment bears no more than a tangential relation to the equivalent in question; or (3) when some other reason exists that suggests that the patentee could not reasonably be expected to have described the insubstantial substitute in question. Festo II, 535 U.S. at 740-41, 122 S.Ct. 1831. TKT/HMR, however, is also correct in asserting that the Supreme Court in Festo II made clear that to rebut the “presumption” of prosecution history es-toppel, a patentee must “show that at the time of the amendment one skilled in the art could not reasonably be expected to have drafted a claim that would have literally encompassed the alleged equivalent.” Festo II, 535 U.S. at 741, 122 S.Ct. 1831. Upon careful review, it seems that this latter standard is a broad, over-arching one that embraces the three situations described above. When any of the three situations exist, the broad, over-arching standard necessarily is met. In other words, if the equivalent was unforeseeable, it would not have been reasonable to expect the patentee to have drafted the claim otherwise. Likewise, if the reason for the amendment was only tangentially related to the equivalent, it would not have been reasonable to expect the patentee to have drafted the claim so that it literally included the equivalent in question; that is, while the patentee perhaps could have drafted the claim otherwise to include the equivalent, it would not be reasonable to have expected it to have done so if the amendment was not even remotely related to the equivalent in question. Finally, the third example simply illustrates that the Supreme Court recognized that the first two rebuttal methods were not exhaustive, that is, that there may yet be another reason why it would be unreasonable to expect the patentee to have drafted the claim to have encompassed the alleged equivalent. This interpretation is also supported by the language of the opinion itself. The Supreme Court, in describing the third rebuttal standard, used the words “some other reason suggesting that the patentee could not reasonably be expected to have described the insubstantial substitute in question,” Festo II, 535 U.S. at 741, 122 S.Ct. 1831 (emphasis added). In using the words “some other reason,” the Supreme Court indicated that the first two methods are merely specific ways to rebut the same broad presumption. Thus, the proper interpretation of the Supreme Court’s language is that the first two methods are included within the broad, over-arching standard and the third is that Court’s way of recognizing that other circumstances may also suffice to rebut the Festo II “presumption.” This reading finds further support in the concluding sentence of this section of the opinion, wherein the Supreme Court summarizes the standard: “[t]he patentee must show that at the time of the amendment one skilled in the art could not reasonably be expected to have drafted a claim that would have literally encompassed the alleged equivalent.” Id. The fact that the Supreme Court summarized its analysis in this way suggests that one broad standard encompasses the three situations previously outlined. Most of the cases that have applied the holdings of Festo II also support this interpretation. In Bosch v. Japan Storage Battery Co., Ltd., 223 F.Supp.2d 1159, 1170 (C.D.Cal.2002), the court listed the three examples that the Supreme Court provided in Festo II and then summarized them by stating “[i]n short, ‘[t]he patentee must show that at the time of the amendment one skilled in the art could not reasonably be expected to have drafted a claim that would have literally encompassed the alleged equivalent.’ ” In Vardon Golf Co., Inc. v. Karsten Mfg. Corp., the court explained that the Supreme Court put the burden of showing that an amendment has not surrendered a particular equivalent on the patentee and implicitly indicated that this burden was “showing] at the time of the amendment one skilled in the art could not reasonably be expected to have drafted a claim that would have literally encompassed the alleged equivalent.” Vardan Golf, 2002 WL 1424567, at *4 (N.D.Ill.2002). Later, when describing specific cases in which this burden was met, it stated that the Supreme Court’s foreseeability example met the broad over-arching standard: “If for example the equivalent was unforeseeable at the time of the application, then the paten-tee could not reasonably be expected to have described the insubstantial substitute in question.” Id. at *4; see also SoundTube, 283 F.Supp.2d at 197 (summarizing the patentee’s argument as “[the patentee] could not have foreseen the SoundTube system during the prosecution of the patent and thus ‘one skilled in the art could not reasonably have been expected to draft claim limitations to literally encompass’ the SoundTube devices”) (emphasis added); Glaxo Wellcome Inc. v. Impax Labs. Inc., 220 F.Supp.2d. 1089, 1098 (N.D.Cal.2002) (summarizing the standard as a single broad, over-arching standard); Conmed Corp. v. Ludlow Corp., 235 F.Supp.2d 109, 122 (N.D.N.Y.2002) (applying the broad, over-arching standard and concluding that the patentee failed to meet its burden); SmithKline Beecham Corp. v. Excel Pharms., Inc., 214 F.Supp.2d 581, 591 (E.D.Va.2002) (stating that, to meet its burden, the patentee must satisfy the broad, over-arching standard); but see Schwing GmbH 305 F.3d at 1329 (stating that the Supreme Court “discussed several ways in which the patentee could overcome [the] presumption” and listing the three examples from Festo II without connecting them to a single, broad, over-arching standard). Thus, this Court interprets Festo II as providing a single standard — albeit a difficult one to satisfy — to determine whether the “presumption” of estoppel has been overcome and as offering three situations in which the articulated standard would be satisfied. b. The Federal Circuit’s Analysis: DIFFERS FROM THIS COURT’S ANALYSIS BUT DOES NOT CHANGE THIS COURT’S ULTIMATE HOLDING. The Federal Circuit holds that there are three separate “criteria” which the paten-tee may meet to rebut the “presumption.” Festo III, 344 F.3d at 1365-66, 1368-70 (“Specifically, the Court enumerated the three ways in which the patentee may overcome the presumption.”). As mentioned above, whether the standard is viewed as three separate criteria or as one over-arching standard, will not, in most cases, change the end-result because the three criteria work in tandem with what this Court viewed as the over-arching standard. In other words, if the equivalent was unforeseeable, or if the reason for the amendment was no more than tangentially related to the equivalent, it would not have been reasonable to expect the patentee to have drafted the claim to have literally encompassed the equivalent. The Federal Circuit’s interpretation nevertheless may make a significant difference in the outcome of cases because it states that the third — the “some other reason” — criterion is to be narrowly construed. Id. at 1368-69. Aside from stating that “a patentee may not rely on the third rebuttal criterion if the alleged equivalent is in the prior art .... ” and that the “shortcomings of language” may satisfy the criterion, the Federal Circuit left to another day further exposition of this third criterion. Id. at 1369-70. 5. What Type Of Evidence May Be Used To Rebut The Presumption? a. The Court’s Original Analysis: Extrinsic evidence may be considered if it does not contradict the intrinsic evidence. Although the rebuttal standard is narrow, the inquiry and analysis to determine if it has been met is in some respects intricate and, therefore, requires resort to extrinsic evidence. The Supreme Court made clear in Festo II that a court must examine the subject matter surrendered by the amendment and the reasonable inferences that can be drawn from the amendment. Festo II, 535 U.S. at 737-38, 122 S.Ct. 1831; Schwing GmbH, 305 F.3d at 1329; Bosch, 223 F.Supp.2d at 1170. This examination is more than a peripheral one. There is no reason why a narrowing amendment should be deemed to relinquish equivalents unforeseeable at the time of the amendment and beyond a fair interpretation of what was surrendered. Nor is there any call to foreclose claims of equivalence for aspects of the invention that have only a peripheral relation to the reason the amendment was submitted. Festo II, 535 U.S. at 738, 122 S.Ct. 1831 (emphasis added). To determine what was fairly surrendered by the amendment, the Court needs to, in many instances, understand the rationale for the amendment. Id. Knowing simply that an amendment was made for reasons related to patenta-bility is not enough. The Court needs to understand more specifically why the exact words or limitations were added or deleted and such an understanding is not always immediately evident in the prosecution history. Often patentees change certain aspects of claims in response to an objection. Other times, such as in the case before the Court, patentees voluntarily make changes even when there is neither a Patent Office objection nor rejection and when no prior art threatens the validity of the invention. Given that the “remarks” that accompany the amendments are cursory at best, in the latter case it is even more difficult to discern the particular rationale for the amendment based on the prosecution history. Amgen I, 126 F.Supp.2d at 135 (“This search for purpose is made more difficult where, as here, there is nothing in the file wrapper as of the date of the amendment indicating that the claims were objectionable to the Patent Office”). Moreover, the “state-of-the-art” at the time of the amendment (a key piece of information necessary to determine foreseeability) generally is not something addressed in the prosecution history — nor are the intricacies of the technology always clear. Therefore, there are instances in which reliance on the prosecution history alone would not inform the court in sufficient detail as to why certain additions and deletions to the claims were made. Notwithstanding these concerns, TKT/ HMR relies on Pioneer Magnetics to argue that only the public prosecution history record can be used to demonstrate the purpose of the amendment and that the Court should not consider any extrinsic evidence in determining whether the rationale for the amendment has no more than a tangential relation to the equivalent in question. TKT/HMR’s argument is unavailing here. First, Pioneer Magnetics is distinguishable from the instant case. In Pioneer Magnetics, when the Federal Circuit stated that only the public record could be used to determine the purpose for the amendment, the court was evaluating whether the amendment was made for pat-entability reasons (a determination made prior to the assessment of whether the “presumption” of prosecution history es-toppel has been overcome). Pioneer Magnetics, 330 F.3d at 1356. Thus, this holding is inapposite to the analysis that occurs after the court has decided that the amendment was a narrowing one made for patentability reasons and that the “presumption” therefore applies. Second, neither Pioneer nor Festo II foreclose the use of extrinsic evidence once the “presumption” of estoppel has been triggered and the patentee is trying to rebut it. See, e.g., Areaux & Owers, supra, at 574 (noting that the Supreme Court did not offer any guidance as to whether intrinsic or extrinsic evidence can be used). Moreover, in explaining that the interpretation of the patent begins — but does not end — with the literal claims and the prosecution history, Festo II apparently gave the patentee leeway to rely on extrinsic evidence to prove that “one skilled in the art could not reasonably be expected to have drafted a claim that would have literally encompassed the alleged equivalent.” Festo II, 535 U.S. at 741, 122 S.Ct. 1831; but see Pavan K. Argarwal, Patenting in Line with the Federal Circuit, 12 Fed. Cir. B.J. 395, 413-14 (2003) (“[W]ith the notice function that the Supreme Court previously announced in Warner-Jenkinson Co. v. Hilton Davis Chemical Co., it would seem appropriate to limit the patentee to the public record of the prosecution as the en banc Federal Circuit decided in Festo.”). Third, the United States Amicus Brief— relied on by the Supreme Court to define the rebuttable “presumption” — argued that extrinsic evidence can be used that explains but does not contradict intrinsic evidence. Brief of Amicus Curiae United States at 23, Festo II, 535 U.S. 722, 122 S.Ct. 1831, 152 L.Ed.2d 944 (2002); Ar-eaux & Owers, supra, at 575-6 (noting that the U.S. Amicus Brief was a clue to what type of evidence the Federal Circuit will allow). Moreover, it specifically urged that facts should be drawn from the specific technology involved. Brief of Amicus Curiae United States at 28 n. 4. Even the Federal Circuit in Festo I (which stated that use of extrinsic evidence would undermine the public notice function) explained that a district court can properly consider any argument made by an attorney that is supported by the prosecution history record. Festo I, 284 F.3d at 586 n. 6. Lastly, common sense dictates that extrinsic evidence may be necessary to meet the rebuttal requirements outlined in Festo II. For example, the prosecution history alone would not show whether an invention, discovery, or technique was foreseeable, or whether a person skilled in the art could have drafted the claim differently. See, e.g., Areaux & Owens, supra, at 575 C‘[I]t seems plain that evidence of foreseeability will not reside in the prosecution history”). Furthermore, it is the prosecution history itself that triggers the “presumption” of estoppel; thus, if the paten-tee is limited to the prosecution history in its efforts to rebut that “presumption,” it would likely never be successful. Like a standard of proof that is too exacting, limiting the patentee to the intrinsic record would in essence create a result similar to the complete bar the Supreme Court overruled in Festo II. For these reasons, in determining whether Amgen has rebutted the “presumption” of estoppel, the Court will examine the prosecution history in light of the presentations made during the trial and in the parties’ submissions. Cf. Canton Bio-Medical, Inc. v. Integrated Liner Tech., Inc., 19 F.Supp.2d 22, 32 (N.D.N.Y.1998) (relying in part on expert opinion to determine what was surrendered with the amendment and holding that “[ajfter considering the arguments of the parties, their briefing and submissions, the entire relevant record, and the applicable law, the [c]ourt finds that the Defendant’s accused process does not infringe the Plaintiffs [ ] patent, as a matter of law, based on the application of prosecution history estoppel In other words, the Court will consider extrinsic evidence. It will do so, however, only when that evidence does not contradict the intrinsic evidence — the patent, the specification, and the prosecution history. Such an examination thus cannot dissuade the Court from giving the public record its due weight — a significant policy on which patent law is based. Moreover, the Court will not go so far as to consider the subjective intent of the patentees when such intent is not expressed in or supported by the patent or file wrapper. “Such testimony cannot guide the court to the proper interpretation when the patent documents themselves do so clearly.” Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1584 (Fed.Cir.1996). When, however, such intent is supported by the prosecution history, the Court will consider it because “a full understanding of what the inventors actually invented and intended to envelop with the claim” guides a court to the proper interpretation. Renishaw PLC. v. Marposs Societa’ per Azioni, 158 F.3d 1243, 1250 (Fed.Cir.1998) (discussing claim construction). These limitations on the Court’s consideration of extrinsic evidence strike the proper balance between supporting the notice functions of the patenting process and protecting the true scope of an inventor’s patent despite the ineptness of language to do so on its own. b. The Federal Circuit’s Analysis: RESTRICTS THIS COURT’S APPROACH The Federal Circuit adopts a more restrictive approach to extrinsic evidence than that set out above. Festo III, 344 F.3d at 1368-70. Both this Court and the Federal Circuit interpret Festo II as allowing consideration of extrinsic evidence when determining whether the first criterion, foreseeability, has been met. Id. The Federal Circuit, however, clearly limits the determination under the second criterion, tangentiality, to intrinsic evidence and strongly suggests that the third criterion should be limited in the same way. Id. This is the crucial difference between its analysis and that of this Court. Notwithstanding the revisions necessary to comport with the Federal Circuit’s analysis, the Court’s holding that Amgen has rebutted the presumption has not changed. The basis for this holding, however, rests on different criteria, as will be explained below. 6. Should Foreseeability Be Analyzed At The Time Of The Amendment Or The Time Of The Original Patent Application? a. The Court’s Original Analysis: Foreseeability Should Be Analyzed At The Time Of The Amendment Some scholars and courts have indicated that the Supreme Court was not clear whether foreseeability should be analyzed at the time of the amendment or at the time of the application. See, e.g., Caliendo, supra, at 321; Fu, supra, at 134 (noting that the Supreme Court was unclear with respect to when the foreseeability test should be applied). This Court, however, holds that Festo II defined the relevant time period as the time of the amendment, not the time of the patent application. First, in Festo II the Supreme Court explicitly stated twice that the relevant time period is the time of the amendment. When it first explains why a narrowing amendment should not be deemed to relinquish all equivalents, it considers foreseeability based upon what was known at the time of the amendment. Festo II, 536 U.S. at 738, 122 S.Ct. 1831. Later, when it summarizes the holding of Festo II, the Federal Circuit again states that the “presumption” may be rebutted when the patentee “show[s] that at the time of the amendment one skilled in the art could not reasonably be expected to have drafted a claim that would have literally encompassed the alleged equivalent.” Id. at 741, 122 S.Ct. 1881 (emphasis added). Although the Supreme Court used the word “application” in describing the foreseeability test at one point, see Festo II, 535 U.S. at 740, 122 S.Ct. 1831 (“The equivalent may have been unforeseeable at the time of the application .... ”), the Court was referring to the application process, not the time at which the application was originally filed. Cf. Johnson & Johnston Assoc. Inc. v. R.E. Serv. Co., 285 F.3d 1046, 1059 (Fed.Cir.2002) (Rader, J., concurring) (“In reaching this result, the court suggested that if variation had been unforeseeable during the application process, the doctrine of equivalents would still have been available to the patentee.”). Second, the Federal Circuit and other federal courts have also interpreted the relevant time reference to be the time of the amendment (not the time of the application). See, e.g., Pioneer Magnetics, 330 F.3d at 1357 (analyzing foreseeability based on what was known at the time of the amendment); SmithKline, 214 F.Supp.2d at 592 (same); Masco Corp. v. United States, 56 Fed. Cl. 400, 412 n. 11 (2003) (noting that there is some support for interpreting Festo II as requiring un-foreseeability at the time of the amendment). Third and finally, common sense dictates the same interpretation. Prosecution history estoppel only arises when an amendment has been made that potentially surrenders an equivalent. See Fu, supra, at 134 (noting that the more logical time to apply the foreseeability test is at the time of the amendment). The key inquiry is what was known at the time the patentee added the words now being used to estop it from arguing the equivalent. Amgen strenuously argues that the relevant time period is the time of the application because when amending a patent application, an applicant is limited to the written description and drawings that were in the application at the original filing date and cannot add new matter to an application, even to correct an error in the specification or claims. Amgen’s Post-Hr’g Mem. [Document No. 742] at 5. This argument is unavailing because a patentee certainly can — instead of amending — file a continuation-in-part application if the original written description and drawings do not lend themselves to the desired amendment. See 35 U.S.C. § 120, 112. In other words, if, as Amgen suggests, there is new matter to add that is necessary to complete or correct the patent description and protect the invention, the patentee can and should re-file the application instead of creating a make-shift amendment to patch up the patent’s deficiencies. Therefore, the Court interprets the Supreme Court’s holding in Festo II as requiring foreseeability to be adjudged relevant to the time the amendment was made. b. The Federal Circuit’s Analysis: SUPPORTS THIS COURT’S CONCLUSION Although the Federal Circuit did not explain its conclusion, the recent Federal Circuit opinion in Festo III makes clear that foreseeability should be analyzed at the time of the amendment. Festo III, 344 F.3d at 1369 (stating repeatedly that this criterion asks “whether the alleged equivalent would have been unforeseeable to one of ordinary skill in the art at the time of the amendment ”) (emphasis added). C. Has Amgen Rebutted The “Presumption” Of Estoppel? The following analysis is conducted in light of the Federal Circuit’s recent decision in Festo III. Applying the rules laid out in Festo II as interpreted by the Federal Circuit in Festo III, the Court begins with the presumption that Amgen has surrendered all the equivalents that fall within the territory between the original claims of the application for the ’080 patent and the subsequently narrowed claims of the ’080 patent. See Festo II, 535 U.S. at 733-34, 122 S.Ct. 1831; Festo III, 344 F.3d at 1367-68. When the application for the ’080 patent was originally filed, it contained 60 claims. These claims did not limit the invention to human EPO nor did they limit the claims to the amino acid sequence of Figure 6. In the third preliminary amendment, Amgen added the following limitation: the “mature human erythropoietin sequence of Figure 6.” Third Preliminary Amendment, Trial Ex. 2005, TKT/HMR’s App. [Document No. 708J, Tab E at 7. As explained in Amgen I, Figure 6 displays the nucleotide series or DNA sequence of human EPO including both ex-ons (the portions of the sequence that code for the desired protein) and introns (the portions of the sequence that do not code for the protein and are spliced out during transcription). Amgen I, 126 F.Supp.2d at 100. Figure 6 also shows a series of co-dons, sets of three adjacent nucleotides that determine which of the twenty amino acids are incorporated into a protein at a particular location. Id. Each amino acid is identified by its three letter abbreviation representing a codon. Id. Figure 6, therefore, demonstrates the deduced amino acid sequence that is arrived at by reading the codons of the DNA encoding the protein. Id. Figure 6 numbers the amino acids from -27 to a final position of 166, which is labeled arginine. Because the original claims covered all human EPO regardless of the number of amino acids, but the amended claims limited the EPO to Figure 6 (depicting a 166 amino acid sequence), Amgen is presumptively barred from claiming equivalent infringement by a human EPO product containing anything other than that depicted in Figure 6, such as HMR/TKT’s EPO which comprises a 165 amino acid sequence. Amgen attempts to overcome the “presumption” by arguing (1) that HMR 4396, that is, a mature human EPO with a 165 amino acid sequence, was not foreseeable at the time of the application; (2) that the rationale for the amendment bears “no more than a tangential relation to the equivalent in question,” Festo II, 535 U.S. at 740, 122 S.Ct. 1831; and (3) that there is another reason why Amgen could not reasonably be expected to have drafted a claim that encompassed the alleged equivalent. TKT/HMR argues that Amgen cannot meet the requirements of Festo II to rebut the presumption of estoppel because (1) Amgen could have made its claim without specifying the amino acid sequence (Figure 6) in its entirety or at all; and (2) the claims of the original ’080 patent covered all EPOs (including the TKT/HMR product) and by amending the claims to include a reference to Figure 6, Amgen surrendered this broad coverage. TKT/HMR’s Mem. in Support re: ’080 [Document No. 679] at 2. Before addressing these arguments, a review of the prosecution history is necessary. 1. The Prosecution History Of The ’080 Patent In the first preliminary amendment, the original 60 claims were canceled and new claims 61-67 added. June 6, 1995 Amendment, TKT/HMR’s App., Tab E. Of importance to this case are claims 61, 62, 63, and 64. 61. An isolated human erythropoietin glycoprotein product not being isolated from human urinary sources having gly-cosylation which differs from that of human urinary erythropoietin. 62. An isolated human erythropoietin glycoprotein product not being isolated from human urinary sources having a higher molecular weight than human urinary erythropoietin as measured by SDS-PAGE. 63. An isolated human erythropoietin glycoprotein product not being isolated from human urinary sources and free of other human proteins. 64. The in vivo biologically active er-ythropoietin product of the process comprising the steps of: (a) growing, under suitable nutrient conditions, host cells transformed or transfected with an isolated DNA sequence selected from the group consisting of (1) the DNA sequences set out in FIGS 5 and 6, (2) the protein coding sequences set out in FIGS 5 and 6, and (3) DNA sequences which hybridize under stringent conditions to the DNA sequences defined in (1) and (2) or their complementary strands; and (b) isolating said erythropoietin product therefrom. Id. Thereafter, in the Second Preliminary Amendment, Amgen canceled product claims 61-63, amended process claim 64 to specify that it was a non-naturally occurring in vivo biologically active EPO product, and added new “product-by-process” claim 68. Id.; Amgen’s Post-Hr’g Mem. in Support at 12, n. 12; December 20, 1995, Second Preliminary Amendment, Trial Ex. 3, Tab 3 at 119-120. 68. A non-naturally occurring erythro-poietin product of the process comprising the steps of: a) growing, under suitable nutrient conditions, host cells transformed or transfected with an isolated DNA sequence encoding the human erythro-poietin amino acid sequence set out in FIG. 6 or a fragment thereof; and b) isolating an erythropoietin product therefrom. Id. Amgen then amended the claims again. In this third preliminary amendment, Am-gen cancelled claims 64-68 and inserted new claims 69-75. Third Preliminary Amendment, Trial Ex. 2005, TKT/HMR’s App., Tab E. Claims 69, 70, and 71 became claims 1, 2, and 3 of the ’080 patent and are, therefore, the claims of interest here. 69. An isolated erythropoietin glyco-protein having the in vivo biological activity of causing bone marrow cells to increase production of reticulocytes and red blood cells, wherein said erythro-poietin glycoprotein comprises the mature erythropoietin amino acid sequence of Figure 6 and has glycosylation which differs from that of human urinary er-ythropoietin. Claim 70. An isolated erythropoietin glycoprotein having the in vivo biological activity of causing bone marrow cells to increase production of reticulocytes and red blood cells, wherein said eryth-ropoietin glycoprotein comprises the mature erythropoietin amino acid sequence of Figure 6 and is not isolated from human urine. Claim 71. A non-naturally occurring er-ythropoietin glycoprotein having the in vivo biological activity of causing bone marrow cells to increase production of reticulocytes and red blood cells, wherein said erythropoietin glycoprotein comprises the mature erythropoietin amino acid sequence of Figure 6. Third Preliminary Amendment, Trial Ex. 2005, TKT/HMR’s App., Tab E at 8. 2. Was The Equivalent Foreseeable? As discussed supra, foreseeability is one of the bases on which to determine whether the standard for rebutting the “presumption” is met. If the equivalent in question was not foreseeable at the time of the amendment, then the patentee can overcome the “presumption.” Unfortunately for Amgen, it supports its foreseeability argument primarily with expert testimony that addresses knowledge of those skilled in the art at the time of the application, as opposed to the time of the amendment (the relevant time period). Festo II, 535 U.S. at 741, 122 S.Ct. 1831. Amgen claims (and TKT/HMR does not dispute) that it was unknown, at the time of the patent application, that the 166th amino acid cleaved off to leave a 165 amino acid sequence. Accordingly, Amgen argues, it was unforeseeable (at the time of the application) that Figure 6’s depiction of a sequence of 166 amino acids did not cover all mature human EPOs (including TKT/HMR’s HMR 4396). Moreover, it argues that it was unforeseeable that the mature human EPO glycoprotein produced in Example 10 would contain only the 1-165 amino acid sequence. Crucially, Amgen made admissions in its submissions and oral argument that it — as well as those skilled in the art — knew at the time of the amendment that human urinary EPO had a 165 amino acid sequence. Amgen’s Mem. in Support at 10; 7/28/03 Mot. Hr’g Tr. at 71, 11. 11-20; 7/31/03 Mot. Hr’g Tr. at 77,11. 12-18. In fact, on October 30,1987, Amgen explained in its FDA product license application that the 166th arginine (depicted in Figure 6) cleaves off leaving 165 amino acids (instead of the originally believed 166): The Arg 166, coded for by the erythro-poietin gene (Section 2.B) appears to be cleaved post-translationally, resulting in a C-terminus residue of Asp 165. The detailed analysis of the C-terminus of erythropoietin is described later in this Section. Trial Ex. 2024 at AM 57 007747. Therefore, Amgen cannot meet its burden here. Amgen’s argument that this admission does not show that it was foreseeable that the amendment (that incorporated the Figure 6 limitation) would be construed by this Court to exclude human EPO with a 165 amino acid sequence is unavailing at this juncture in the analysis. Simply because the Court’s construction (that resulted in a complete surrender of an equivalent human EPO with a 165 amino acid sequence) was not foreseeable at the time of the amendment does not mean that the equivalent was not itself foreseeable— which is the correct inquiry. See Masco, 56 Fed. Cl. at 413 (finding unavailing pat-entee’s argument that surrender was not foreseeable because it did not have the Court’s claim construction); SmithKline, 214 F.Supp.2d at 592 n. 23 (“[T]he issue before this court is whether the patentee had the scientific ability to redraft the claims more broadly _”). Although this places a “premium on forethought of patent drafting,” this premium is not new to the doctrine. Sage Prods., Inc. v. Devon Indus., Inc., 126 F.3d 1420, 1425 (Fed. Cir.1997); Johnson & Johnston, 285 F.3d at 1057 (Rader, J., concurring) (“A foreseeability bar thus places a premium on claim drafting and enhances the notice function of claims. To restate, if one of ordinary skill in the relevant art would reasonably anticipate ways to evade the literal claim language, the patent applicant has an obligation to cast its claims to provide notice of that coverage. In other words, the patentee has an obligation to draft claims that capture all reasonably foreseeable ways to practice the invention”). Here, given its knowledge of human EPO having 165 amino acids, Amgen had “every incentive to redraft the claims as broadly as possible in an effort [to] surrender no more subject matter than necessary to secure the patent.” SmithKline, 214 F.Supp.2d at 592. For example, Amgen might have deleted the reference to Figure 6 altogether and claimed “mature human EPO” instead of limiting it to a sequence. Indeed, Amgen admits that it “could have sought broader claims that literally encompassed human EPO with a 165 amino acid sequence, and did in fact do so in the ’422 patent [U.S. Patent No. 5,955,422].” Therefore, Amgen cannot prevail under this prong of the analysis. The determinative factor here is that the alleged equivalent was foreseeable. In fact, it was known and could easily have been encompassed in the amendment. Thus, Amgen has not met its burden with respect to the foreseeability criterion. 3. Was The Rationale Underlying The Amendment No More Than Tangentially Related To The Equivalent? Although the Court has determined that the 1-165 amino acid human EPO equivalent was indeed foreseeable, Amgen can rebut the “presumption” of prosecution history estoppel if it can show by a preponderance of the evidence that the rationale underlying the amendment was only tangentially related to the equivalent. Festo II, 585 U.S. at 740, 122 S.Ct. 1881. With respect to this standard, more than the others, the purpose of the amendment comes to the forefront of the analysis. Contrary to some scholars’ views, the correct inquiry is not whether the amendment itself narrows the scope of a claim in a way that affects the equivalent in question. If this were the test, it would be an impassable one — the only reason why the dispute arises is because the equivalent is related to the amendment and thereby affected. The correct inquiry is whether the rationale underlying the amendment, the “reason the amendment was submitted”— not the amendment itself — is more than peripherally related to the equivalent in question. Festo II, 535 U.S. at 738, 740, 122 S.Ct. 1831 (“Nor is there any call to foreclose claims of equivalence for aspects of the invention that have only a peripheral relation to the reason the amendment was submitted.... [T]he rationale underlying the amendment may bear no more than a tangential relation to the equivalent in question ....”) (emphasis added). Thus, the Court must delve deeper to determine whether the rationale underlying the amendment to the ’080 patent was tangential to the equivalent in question. While it is undisputed that the amendment was made to avoid a double patenting objection, the parties disagree about why the amendment was so constructed, that is, why Amgen used the exact language it did to distinguish the ’080 patent from Am-gen’s ’933 patent. Moreover, in light of the Federal Circuit’s mandate that the Court rely only on intrinsic evidence in this criterion, determining the purpose of the amendment is made even more “thorny” because the amendment was not made to address a rejection or objection actually made or described by the Patent Office. Amgen I, 126 F.Supp.2d at 135. Amgen argues primarily that it amended its claim to specify that the ’080 patent referred to the mature human EPO (which can be described as having the amino acid sequence of Figure 6) and not to distinguish or exclude a 165 amino acid human EPO such as TKT/HMR’s HMR 4396. Amgen’s Mem. in Opp’n at 12, The prosecution history supports Am-gen’s contention. Amgen’s ’933 patent issued just before this amendment was made. It claimed human and non-human EPO. When the application for the ’080 patent was filed, it contained 60 claims, none of which limited the EPO protein products to “human” EPO. Amgen’s Pos1>-Hr’g Mem. at 11. As described in detail above, in a preliminary amendment, those original 60 claims were canceled and new claims 61-67 were added. June 6, 1995 Preliminary Amendment, TKT/HMR’s App., Tab E. Claims 61-63, product claims, were indeed limited to a human EPO gly-coprotein product. Id. In a second preliminary amendment, however, all but two claims (which were amended) were can-celled, and a new “product-by-process” claim was added. Amgen’s Post-Hr’g Mem. at 12; Second Preliminary Amendment, Trial Ex. 3, Tab 3 at 119-120. At this point, there is no dispute that the claims, as depicted in the second preliminary amendment were not limited to “human” EPO.