Honeywell International Inc. v. Hamilton Sundstrand Corp.

370 F.3d 1131, 2004 WL 1202997

• Court: Court of Appeals for the Federal Circuit
• Decided: June 2, 2004
• Docket: Nos. 02-1005, 02-1082
• Status: Published

Opinions

Opinion for the court filed by Circuit Judge DYK, in which Chief Judge MAYER and Circuit Judges MICHEL, LOURIE, CLEVENGER, RADER, SCHALL, BRYSON, GAJARSA, LINN, and PROST join. Opinion dissenting in part filed by Circuit Judge NEWMAN.

DYK, Circuit Judge.

Honeywell International Inc. and Honeywell Intellectual Properties, Inc. (collectively “Honeywell”), the assignees of the patents in suit, brought suit against Hamilton Sundstrand Corporation (“Sundstrand”) for infringement of claims 8,10,11,19 and 23 of United States Patent No. 4,380,893 (the “'893 patent”) and claim 4 of Patent No. 4,428,194 (the “'194 patent”). All of the asserted independent claims were originally dependent claims that were rewritten into their present independent form during prosecution. The broader original independent claims were cancelled.

The jury found that the patents in suit were valid and, although not literally infringed, infringed under the doctrine of equivalents. The district court entered judgment against Sundstrand. Honeywell Int’l Inc. v. Hamilton Sundstrand Corp., 166 F.Supp.2d 1008 (D.Del.2001).

Following our recent decisions in Deering Precision Instruments, L.L.C. v. Vector Distribution Systems, Inc., 347 F.3d 1314 (Fed.Cir.2003), and Ranbaxy Pharmaceuticals, Inc. v. Apotex, Inc., 350 F.3d 1235 (Fed.Cir.2003), we hold that the rewriting of dependent claims into independent form coupled with the cancellation of the original independent claims creates a presumption of prosecution history estop-pel. Accordingly we vacate the judgment of infringement and remand for determination of whether Honeywell can rebut the presumption of surrender under Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 122 S.Ct. 1831, 152 L.Ed.2d 944 (2002), remanded to 344 F.3d 1359 (Fed.Cir.2003) (en banc). We affirm the district court’s judgment rejecting Sundstrand’s counterclaims of invalidity.

BACKGROUND

I

The Honeywell patents are directed to an aircraft auxiliary power unit (“APU”), a small gas turbine engine usually located in the tail section of an airplane. The APU generates electricity and incorporates a load compressor to provide compressed air needed both to start the aircraft’s main engines and to control the environment of the aircraft’s cabin during flight. During flight, the amount of compressed air required for these purposes fluctuates substantially. A valve is used to control the amount of air exiting the compressor through the main air duct, which supplies compressed air to the aircraft’s systems. Rapid changes in the demand for compressed air needed can produce “surge,” a flow instability that occurs when pressure builds up in the main air duct. In a surge condition, the air attempting to exit the compressor’s main air duct is unable to do so. Instead the airflow reverses direction, surging back into the compressor and potentially damaging the APU. The APU must therefore be designed in such a way as to control surge. Prior systems controlled surge by drawing in more air than was needed and venting (bleeding) the excess through a surge bleed valve in order to reduce pressure in the main air duct. Such systems maintained sufficient output airflow, effectively controlling surge, but were inefficient in operation and wasteful of energy.

The Honeywell APU is designed to be more efficient by avoiding excess air bleeding in its control of surge. To do this it is necessary to determine when and how far to open the surge bleed valve in order to maintain a level of flow sufficient to avoid surge. To reach this end, Honeywell’s invention establishes a “set point” that represents the minimum flow at which surge can safely be avoided. In the claimed invention, “[ajmbient air ... is drawn through a set of adjustable inlet guide vanes.” '893 patent, col. 3, 11.64-65. The value of the set point is selected “as a function of the position of said inlet guide vanes.” Id., col. 12,11.11-12; see also '194 patent, col. 12, 11.15-16. The set point is compared to a “flow-related parameter” that represents airflow out of the compressor as determined by a sensor. '893 patent, col. 2, 11.47-48; '194 patent, col. 2, 11.48-49. Thus a comparison is made between the actual flow conditions (represented by the flow-related parameter) and the desired flow conditions (represented by the set point). If the system determines that airflow out of the main air duct is too low, the surge bleed valve will be opened to prevent the build up of excess pressure leading to surge.

II

The '893 and '194 patents resulted from a common application filed February 19, 1981. The specification of both patents is identical. Only claims 8, 10, 11, 19 and 28 of the '893 patent and claim 4 of the '194 patent are at issue in this case. Each of these claims requires the APU to include inlet guide vanes and requires the operation of the surge bleed valve to be a function of inlet guide vane position. Claim 8 is representative of the apparatus claimed in the '893 patent:

8. A gas turbine engine accessory power unit having a fluctuating compressed air supply demand, said accessory power unit comprising:

(a) a compressor having adjustable inlet guide vanes;

(b) duct means for receiving compressed air discharged from said compressor and supplying the received air to the pneumatically-powered apparatus;

(c) surge bleed means operable to exhaust from said duct means a selectively variable quantity of air to assure at least a predetermined minimum flow rate through said duct means and thereby prevent surge of said compressor;

(d) sensing means for sensing the value of a predetermined, flow-related parameter within said duct means and generating an output signal indicative of said value, said value of said flow-related parameter being substantially independent of the temperature of the compressed air;

(e) comparator means for receiving said sensing means output signal and generating an error signal representing the difference between the sensed value of said parameter and a desired value thereof, said comparator means having an adjustable control set point representing said desired value of said parameter;

(f) means for transmitting to said comparator means a reset signal for varying said set point as a junction of the position of said inlet guide vanes in accordance with a predetermined reset schedule; and

(g)control means for receiving said error signal and transmitting to said surge bleed means a control signal to operate said surge bleed means, the magnitude of said control signal having, relative to the magnitude of said error signal, a proportional component and an integral component, whereby said minimum flow rate though said duct means is essentially constant regardless of the compressed air supply demand of the pneumatically-powered apparatus.

'893 patent, col. 11, 1.52 — col. 12, 1.23 (emphases added). Claim 4 of the '194 patent claims a method of controlling surge in an APU:

4. A method of utilizing a compressor of a gas turbine engine to power pneumatically-operated apparatus having a variable inlet air flow demand, the compressor having adjustable inlet guide vanes, said method comprising the steps of:

(a) interconnecting a supply duct between the compressor and the pneumatically-operated apparatus;

(b) flowing discharge air from the compressor through said supply duct to the pneumatically-operated apparatus;

(c) maintaining an essentially constant minimum supply duct flow rate, despite fluctuations in the flow rate of air received by the pneumatically-operated apparatus, by exhausting air from said supply duct in response to variations therein of the value of a predetermined, flow-related parameter, the flow rate of air exhausted from said supply duct being related to the magnitude of said parameter value variations in both a proportional and time-integral manner, said maintaining step including the steps of providing an outlet passage from said supply duct, positioning in said outlet passage a surge bleed valve operable to selectively vary the flow of air outwardly though said outlet passage, generating an integral control signal in response to said variation in said flow-related parameter, generating a proportional control signal in response to said variations in said flow-related parameter, and simultaneously utilizing said integral and proportional control signals to operate said surge bleed valve;

(d) adjusting the relationship between the magnitudes of said integral and proportional control signals and the magnitudes of said parameter variations as a function of the position of the inlet guide vanes.

'194 patent, col. 10, 1.64 — col. 12, 1.16 (emphases added).

Ill

Sundstrand manufactures an APU device, the APS 3200, which also uses an active surge control system that compares a flow-related parameter to a set point and adjusts the surge bleed valve in response. Sundstrand’s device establishes a set point that is dependent upon ambient air temperature, rather than a measurement of inlet guide vane position. This set point is compared to a flow-related parameter called DELPQP. Because of characteristics unique to DELPQP,¹ the APS 3200 blocks control signals used to operate the surge bleed valve during extreme high flow conditions. This prevents unnecessary bleeding of air during such conditions. The determination of whether to block these control signals is based in part on the position of the APS 3200’s inlet guide vanes.

Only infringement under the doctrine of equivalents is at issue in this appeal. Honeywell concedes that the inlet guide vane limitation² is not literally met by the accused device. However, there is substantial disagreement as to the function of the inlet guide vanes required by the claims and whether inlet guide vane position performs an equivalent function in the accused device. Sundstrand contends that the claimed function is to use inlet guide vane position to establish the set point. It urges that the APS 3200 uses inlet guide vane position for a very different function, 1.e., to determine when to block control signals used to operate the surge bleed valve. Honeywell disagrees, arguing that the function of the inlet guide vane limitation “is to incorporate the position of the [inlet guide vanes] into the surge control system.” (Reply Br. for Pls.-Appellants at 23 (claim 4); see also id. at 25 (claim 8).) It argues that this function is met because the APS 8200 uses inlet guide vane position, in addition to temperature, to efficiently control surge. Unfortunately, by agreement of the parties, the district court did not construe the claim language defining the function of inlet guide vane position in the '893 patent, and the court’s construction of step (d) of claim 4 of the '194 patent and its jury instruction were somewhat cryptic.³

IV

Honeywell filed this suit on May 17, 1999, alleging that the APS 3200 infringed both the '893 and '194 patents. Sundst-rand denied that its device infringed the patents.

Sundstrand further pointed out that all of the asserted claims were originally dependent on other claims in Honeywell’s patent applications (application claims 16 and 32 of the '893 patent and application claims 48 and 49 of the '194 patent) that did not contain the inlet guide vane limitation. These claims were rejected as obvious in light of the prior art during the prosecution of Honeywell’s patents. Application claims 17 and 35 of the '893 patent and application claim 51 of the '194 patent, which further included the inlet guide vane limitation,⁴ were not allowed only because they were dependent on the rejected independent application claims.⁵ The examiner indicated that application claims 17, 35 and 51 would be allowable if rewritten into independent form. In response, the rejected independent claims were cancelled and application claims 17, 35 and 51 were amended to expressly incorporate the limitations of the rejected independent claims. The amended application claims issued respectively as claims 8 and 19 of the '893 patent and claim 4 of the '194 patent, which are the only independent claims found to be infringed by the jury and at issue in this dispute. Claims 10, 11 and 23 of the '893 patent, also found to be infringed, are dependent on claims 8 and 19 and thus include the inlet guide vane limitation.

Before the district court, Sundstrand urged that claims 8 and 19 of the '893 patent and claim 4 of the '194 patent were narrowed by amendment and that prosecution history estoppel barred all equivalents for the inlet guide vane limitation under Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 234 F.3d 558 (Fed.Cir.2000) (en banc). In the alternative, Sundstrand argued that there was no infringement under the doctrine of equivalents because the APS 3200 used inlet guide vane position for a “completely different function” (i.e., to determine when to block the control signal operating the surge bleed valve, as opposed to using inlet guide vane position to determine when and how much to open that valve). Affirmative defenses and counterclaims urging that the '893 and '194 patents were invalid as anticipated, obvious in view of the prior art, and barred by the on-sale bar of 35 U.S.C. § 102(b) were also asserted. Finally, Sundstrand argued that damages, if any, were limited to those incurred after February 3, 1999, the date it received actual notice of Honeywell’s infringement allegations, because the patentee had. failed to mark its products in accordance with 35 U.S.C. § 287. Sundstrand moved for summary judgment on each of these arguments.

On January 8, 2001, the district court, while acknowledging that Sundstrand’s argument had “superficial appeal,” rejected its motion for summary judgment on prosecution history estoppel. Honeywell Int’l Inc. v. Hamilton Sundstrand Corp., No. 99-309 GMS, slip op. at 10, 2001 WL 66348 (D.Del. Jan. 8, 2001). The court held that because the claims were merely rewritten into independent form, the “elements at issue were not amended” and “Honeywell did not give up an embodiment of the invention with the inlet guide vane” limitation. Id. at 10-11. Sundstrand’s other summary judgment motions for invalidity and infringement were denied because genuine issues of material fact remained. However, the district court granted Sundstrand’s summary judgment motion on the marking issue and limited damages to those incurred after February 3, 1999. Honeywell Int’l Inc. v. Hamilton Sundstrand Corp., No. 99-309 GMS, 2001 WL 66345 (D.Del. Jan. 4, 2001). Subsequently, the district court clarified its decision to limit damages, holding that Honeywell could not recover damages on sales pursuant to contracts made prior to February 3, 1999, even if delivery occurred after that date. Honeywell Int’l Inc. v. Hamilton Sundstrand Corp., No. 99-309 GMS (D.Del. Feb. 8, 2001).

In February 2001 the case was tried before a jury. The jury found that all of the asserted claims of the '893 and '194 patents were not invalid. It rejected Honeywell’s contention that Sundstrand had literally infringed the '194 patent, but found claims 8, 10, 11, 19 and 23 of the '893 patent and claim 4 of the '194 patent infringed under the doctrine of equivalents. The jury further found willfulness, and awarded $1,578,065 in reasonable royalty compensation and $45,000,000 in price erosion damages. Judgment in accordance with the jury verdict was entered on February 20, 2001. On September 27, 2001, the court denied Sundstrand’s motions for judgment as a matter of law (“JMOL”) and a new trial. The court also denied Honeywell’s motion for JMOL on literal infringement and its motion for enhanced damages, attorneys’ fees and costs, including expert witness costs.

Honeywell timely appealed the district court’s decisions limiting its actual damages. Honeywell did not appeal the judgment of no literal infringement. Sundstrand cross-appealed, challenging the district court’s determinations of infringement under the doctrine of equivalents and the decision rejecting its claims of invalidity. We have jurisdiction pursuant to 28 U.S.C. § 1295(a)(1).⁶ This case was originally heard by a panel of this court on August 7, 2002. The court sua sponte ordered en banc review on February 5, 2004.

DISCUSSION

We review the district court’s denial of a motion for JMOL without deference, applying the same standard employed by the district court. Ericsson, Inc. v. Harris Corp., 352 F.3d 1369, 1373 (Fed.Cir.2003). That standard requires us to “determine whether viewing the evidence in the light most favorable to the non-moving party, and giving the non-movant the benefit of all reasonable inferences, there is sufficient evidence of record to support a jury verdict in favor of the nonmovant.” Id. (internal quotation marks omitted). ‘We review the denial of a motion for a new trial for an abuse of discretion.” Hewlett-Packard Co. v. Mustek Sys., Inc., 340 F.3d 1314, 1318 (Fed.Cir.2003). Whether a patentee is presumptively estopped from asserting equivalents for an amended claim element is a question of law that we review without deference. Ranbaxy, 350 F.3d at 1240.

I. Prosecution History Estoppel A

At the outset, this case requires us to determine first whether a narrowing amendment to a patent claim that adds an additional claim limitation creates a presumptive surrender of equivalents under the Supreme Courts decisions in Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17, 117 S.Ct. 1040, 137 L.Ed.2d 146 (1997), and Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 122 S.Ct. 1831, 152 L.Ed.2d 944 (2002) (“Festo ”), and under our recent decision in Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 344 F.3d 1359 (Fed.Cir.2003) (en banc) (“Festo II ”), following the Supreme Courts remand. We hold that it does.

“The doctrine of equivalents allows the patentee to claim those insubstantial alterations that were not captured in drafting the original patent claim but which could be created through trivial changes.” Festo, 535 U.S. at 733, 122 S.Ct. 1831. An element in the accused device is equivalent to a claim limitation if the only differences between the two are insubstantial. Eagle Comtronics, Inc. v. Arrow Communication Labs., Inc., 305 F.3d 1303, 1315 (Fed.Cir.2002) (citing Warner-Jenkinson, 520 U.S. at 40, 117 S.Ct. 1040). However, prosecution history estoppel may bar the patentee from asserting equivalents if the scope of the claims has been narrowed by amendment during prosecution. Festo, 535 U.S. at 733-34, 122 S.Ct. 1831. “Estoppel arises when an amendment is made to secure the patent and the amendment narrows the patents scope.” Id. at 736, 122 S.Ct. 1831. The basic theory is that:

[w]hen ... the patentee originally claimed the subject matter alleged to infringe but then narrowed the claim in response to a rejection, he may not argue that the surrendered territory comprised unforeseen subject matter that should be deemed equivalent to the literal claims of the issued patent.... [H]is decision to ... submit an amended claim is taken as a concession that the invention as patented does not reach as far as the original claim.

Id. at 733-34, 122 S.Ct. 1831. However, as we recently explained en banc following the Supreme Courts remand in Festo, the presumption of surrender may be rebutted if the patentee can demonstrate that: (1) “the alleged equivalent would have been unforeseeable at the time ... the narrowing amendment” was made; (2) “the rationale underlying the narrowing amendment bore no more than a tangential relation to the equivalent” at issue; or (3) “there was ‘some other reason’ suggesting that the patentee could not reasonably have been expected to have described the alleged equivalent.” Festo II, 344 F.3d at 1368 (quoting Festo, 535 U.S. at 741, 122 S.Ct. 1831).

The Supreme Court addressed the effect of a narrowing amendment on the scope of equivalents in Warner-Jenkinson and Fes-to. These decisions make clear that a narrowing amendment may occur when either (1) a preexisting claim limitation is narrowed by amendment or (2) a new claim limitation is added by amendment. These decisions make no distinction between the narrowing of a preexisting limitation and the addition of a new limitation. Either amendment will give rise to a presumptive estoppel if made for a reason related to patentability.

That the addition of a claim limitation constitutes a narrowing amendment is manifest in the language of both Warner-Jenkinson and Festo. In both of these decisions the Supreme Court indicated that amending to “introduce a new element,” Warner-Jenkinson, 520 U.S. at 33, 117 S.Ct. 1040, or “add[ ] a new limitation,” Festo, 535 U.S. at 728, 122 S.Ct. 1831, may give rise to a presumption of surrender. This language is not dictum. Both Warner-J enkinson and Festo directly held that amendments that added new limitations could give rise to an estoppel. For example, in Wamer-Jenkinson, the paten-tee claimed an “ultrafiltration” process for purifying dye. 520 U.S. at 22, 117 S.Ct. 1040. Originally the claims at issue required “ultrafiltration through a membrane having nominal pore diameter of 5-15 Angstroms under a hydrostatic pressure of approximately 200 to 400 p.si.g .... to thereby cause separation of said impurities from said dye.” Id. During prosecution, the inventors added a new limitation, which narrowed the scope of the claimed invention from processes conducted at any pH to those occurring “at a pH from approximately 6.0 to 9.0.” Id. The Supreme Court expressly treated this amendment as “introducing] a new element” to the claims at issue, further holding that “application of the doctrine of equivalents as to that [added] element” would be barred unless the patentee could show a reason for the amendment sufficient to avoid estoppel. Id. at 33-34, 117 S.Ct. 1040.

Festo too involved amendments that added new limitations to the claims. There two patents were at issue, the Stoll and Carroll patents. During prosecution an additional limitation was added to the Stoll patent requiring that the claimed invention include “a cylindrical sleeve made of a magnetizable material.” Festo II, 344 F.3d at 1371 (emphasis omitted). An additional limitation requiring “a pair of resilient sealing rings” was also added during reexamination to claim 1 of the Carroll patent, which previously “made no reference to sealing rings.” Id. at 1372. The Supreme Court referred to both of these amendments as “add[ing] a new limitation,” 535 U.S. at 728, 122 S.Ct. 1831, and held that they gave rise to a presumptive surrender of equivalents. Id. at 741, 122 S.Ct. 1831; see also, e.g., I.T.S. Rubber Co. v. Essex Rubber Co., 272 U.S. 429, 443, 47 S.Ct. 136, 71 L.Ed. 335 (1926); Shepard v. Carrigan, 116 U.S. 593, 597, 6 S.Ct. 493, 29 L.Ed. 723 (1886) (“Where an applicant for a patent ... is compelled by the rejection of his application ... to narrow his claim by the introduction of a new element, he cannot after the issue of the patent broaden his claim by dropping the element which he was compelled to include in order to secure his patent.” (emphasis added)).

It is therefore clear that the addition of a new claim limitation can give rise to a presumption of prosecution history estoppel, just like an amendment that narrows a preexisting claim limitation. In either case, the narrowing amendment, if made for a reason related to patentability, will give rise to a presumption of surrender. If only narrowing amendments to preexisting claim limitations could give rise to the presumption, the purpose of preventing patentees from recapturing subject matter conceded during prosecution would be undermined. Astute practitioners could, through clever claim drafting, elect to treat most, if not all, amendments as merely adding new claim limitations rather than narrowing preexisting ones. For these reasons, we hold that an amendment adding a new claim limitation constitutes a narrowing amendment that may give rise to an estoppel.

B

We must next address whether rewriting a dependent claim into independent form, coupled with the cancellation of the original independent claim, constitutes a narrowing amendment when the dependent claim includes an additional claim limitation not found in the cancelled independent claim or circumscribes a limitation found in the cancelled independent claim.

In this case there is no question that the original independent claims (application claims 16 and 32 of '893 patent and application claims 48 and 49 of the '194 patent) were rejected for reasons related to pat-entability. All of the original independent claims were rejected as obvious in view of the prior art. The original independent claim upon which application claim 35 depended was also rejected as indefinite under 35 U.S.C. § 112, paragraph two. These rejected independent claims were can-celled and the dependent claims (application claims 17 and 35 of the '893 patent and claim 51 of the '194 patent) were rewritten into independent form in order to secure their allowance.

A presumption of surrender therefore arises if rewriting the dependent claims into independent form, along with canceling the original independent claims, constitutes a narrowing amendment. Honeywell argues that prosecution history estoppel cannot occur where a dependent claim is merely rewritten into independent form. Honeywell contends that, although it surrendered its broader independent claims, there is no presumption of surrender because the scope of the rewritten claims themselves has not been narrowed. We disagree.

In Festo the Supreme Court held that the proper focus is whether the amendment narrows the overall scope" of the claimed subject matter. See 535 U.S. at 736-37, 122 S.Ct. 1831. There the United States in its amicus curiae brief cited the district court’s opinion in this very case. Honeywell itself notes that the government in Festo urged the Court to adopt the position that rewriting a dependent claim into independent form cannot give rise to a presumption of surrender.⁷ (Reply Br. for Pls.-Appellants at 16-17.) The Supreme Court, while approvingly citing the government’s positions with respect to other issues, see, e.g., Festo, 535 U.S. at 740, 122 S.Ct. 1831, rejected the position of the government in this respect, stating that rewriting a dependent claim in independent form creates a presumptive surrender if the amendment is “made to secure the patent,” id. at 736. The Court held that:

The PTO might require the applicant to clarify an ambiguous term, to improve the translation of a foreign word, or to reunite a dependent claim as an independent one. In these cases, petitioner argues, the applicant has no intention of surrendering subject matter and should not be estopped from challenging equivalent devices. While this may be true in some cases, petitioner’s argument conflates the patentee’s reason for making the amendment with the impact the amendment has on the subject matter.

Estoppel arises when an amendment is made to secure the patent and the amendment narrows the patent’s scope. If a § 112 amendment is truly cosmetic, then it would not narrow the patent’s scope or raise an estoppel. On the other hand, if a § 112 amendment is necessary and narrows the patent’s scope — even if only for the purpose of better description-estoppel may apply. A patentee who narrows a claim as a condition for obtaining a patent disavows his claim to the broader subject matter, whether the amendment was made to avoid the prior art or to comply with § 112. We must regard the patentee as having conceded an inability to claim the broader subject matter or at least as having abandoned his right to appeal a rejection. In either case estoppel may apply.

Id. at 736-37, 122 S.Ct. 1831 (emphases added). Thus, the fact that the scope of the rewritten claim has remained unchanged will not preclude the application of prosecution history estoppel if, by canceling the original independent claim and rewriting the dependent claims into independent form, the scope of subject matter claimed in the independent claim has been narrowed to secure the patent.⁸

This is the rule we have consistently-applied in our post-Festo decisions. First, in Deeñng we held that canceling a broader independent claim and replacing it with a dependent claim rewritten into independent form was a “clear surrender of the broader subject matter” that presumptively barred application of the doctrine of equivalents. 347 F.3d at 1325. There the patentee’s original claim 1 defined a portable scale including a sliding weight that moved along a beam to indicate the weight of a load placed on the opposite end. Id. at 1317. Dependent claim 3 added a “Zero Position Limitation” requiring that the zero position of the sliding weight be “in an imaginary plane containing the fulcrum of the beam.” Id. at 1318-19 (emphasis omitted). Claim 1 was rejected as obvious during prosecution. Id. at 1319. The pat-entees canceled claim 1 and rewrote claim 3 (new application claim 11) in independent form. Id. Following the rule announced by the Supreme Court in Festo, we rejected the argument that the amendment was merely “cosmetic.” Id. at 1326. We held that this was a narrowing amendment because “the patentees clearly disclaimed the territory between the original claim 1 and new claim 1 as issued [application claim 11].” Id. at 1325. Consequently, the “addition of independent claim 11, coupled with the clear surrender of the broader subject matter of the deleted original independent claim presumptively” barred the patentee from arguing equivalents related to the zero position of the sliding weight. Id.

So too, in Ranbaxy the patentee’s original independent claim was for a chemical process that involved dissolving starting material into “a highly polar organic solvent.” 350 F.3d at 1237. Dependent claims 3, 5 and 7 further limited the highly polar organic solvent limitation of claim 1 to narrower categories of solvents, ie., sulfoxides, amides and formic acid respectively. Id. The examiner rejected claim 1 as obvious and indefinite in the first office action, but indicated that claims 3, 5 and 7 would be allowable if rewritten into independent form. Id. at 1238. The patentee responded by canceling claims 1, 3, 5 and 7 and adding new claim 11, which was identical to claim 1 except that it limited the highly polar organic solvent limitation to “the group consisting of a sulfoxide, an amide and formic acid,” ie., the patentee rewrote the dependent claims into a single, new independent claim. Id. While noting that the question of whether there was a presumption of estoppel “is best dealt with on a case-by-case basis,” id. at 1240, we held that if the amendment “surrendered subject matter that was originally claimed for reasons related to patentability,” there is a presumption of estoppel, id. (quoting Deeñng, 347 F.3d at 1325). Relying on Festo and Deeñng, we held that there was a clear surrender of subject matter because the narrower rewritten claim had been substituted for the broader original independent claim. Id. As a result, the patentee was presumed to have “surrendered the equivalents that may have been encompassed by ‘highly polar solvent’ ” as originally claimed. Id. at 1241.

The approach of these cases is consistent not only with the language of Festo, but also with its theory. In Festo the Supreme Court explained that “[a] paten-tee’s decision to narrow his claims through amendment may be presumed to be a general disclaimer of the territory between the original claim and the amended claim.” 535 U.S. at 740, 122 S.Ct. 1831. When the scope of the patent claim is narrowed to secure the patent, the court “must regard the patentee as having conceded an inability to claim the broader subject matter.” Id. at 737, 122 S.Ct. 1831. The scope of the patentee’s concession is determined on a limitation-by-limitation basis. See Festo II, 344 F.3d at 1367. It necessarily follows that the presumption of surrender applies only to the amended or newly added limitation; there is no surrender of territory as to unamended limitations that were present in the original claim. Thus, when a claim is rewritten from dependent into independent form and the original independent claim is cancelled, “the correct focus is on whether [the] amendment surrendered subject matter.” Ranbaxy, 350 F.3d at 1240 (quoting Deering, 347 F.3d at 1325) (alteration in original). 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.

In this case there is a presumptive surrender of all equivalents to the inlet guide vane limitation. The only independent claims asserted in this case, claims 4, 8 and 19, were originally dependent on independent application claims 16, 32, 48 and 49, which did not include the inlet guide vane limitation. Claims 4, 8 and 19 included the inlet guide vane limitation. Claims 4, 8 and 19 were rewritten into independent form, and the original independent claims were cancelled, effectively adding the inlet guide vane limitation to the claimed invention. Honeywell is presumptively es-topped from recapturing equivalents to the inlet guide vane limitation.

C

This however is not the end of the matter. In our first en banc decision in Festo, 234 F.3d 558, we held that narrowing a claim element results in a complete surrender of equivalents with respect to that element. Id. at 574. The Supreme Court disagreed. While holding that under such circumstances there was a presumptive surrender as to the entire limitation, the Court held that this presumption could be rebutted in one of three ways. See Festo, 535 U.S. at 740-41, 122 S.Ct. 1831. As made clear in Festo II, the patentee can rebut the presumption of surrender by showing either:

that the alleged equivalent would have been unforeseeable at the time of the narrowing amendment, that the rationale underlying the narrowing amendment bore no more than a tangential relation to the equivalent in question, or that there was some other reason suggesting that the patentee could not reasonably have been expected to have described the alleged equivalent.

344 F.3d at 1368 (quoting Festo, 535 U.S. at 741, 122 S.Ct. 1831). As was the case in Festo II, we think the issue of whether the patentee can overcome the presumption is best addressed, in the first instance, by the district court, and we remand for that purpose.

We do not address Sundstrands other challenge to the verdict of infringement since it is conceded that the jury verdict cannot stand if Honeywell is not entitled to equivalents with respect to the inlet guide vane limitation. In view of our disposition vacating the judgment of infringement, we also need not address Honeywells challenges to the district courts rulings limiting damages.

II. Invalidity

We turn now to the issue of Sundst-rand’s counterclaims for invalidity. Sundstrand argues that the asserted claims of the '893 and '194 patents are invalid under the on-sale bar, anticipated and obvious. Since the ultimate issue of validity was submitted to the jury, we assume that all underlying factual issues were resolved in favor of the verdict winner. Hewlett-Packard, 340 F.3d at 1325. We review the jury’s factual determinations for substantial evidence. Id.; Minn. Mining & Mfg. Co. v. Chemque, Inc., 303 F.3d 1294, 1305 (Fed.Cir.2002).

Substantial evidence supports the jury’s conclusion that the claims at issue were not invalid under the on-sale bar. Under Pfaff v. Wells Electronics, Inc., 525 U.S. 55, 119 S.Ct. 304, 142 L.Ed.2d 261 (1998), the on-sale bar cannot arise unless the invention was (1) the subject of a commercial offer for sale and (2) “ready for patenting” prior to the critical date. Id. at 67, 119 S.Ct. 304. An invention is ready for patenting if it was “re-ducted] to practice before the critical date; or [if] prior to the critical date the inventor had prepared drawings or other descriptions of the invention that were sufficiently specific to enable a person skilled in the art to practice the invention.” Id. at 67-68, 119 S.Ct. 304. Here Sundstrand urges that certain drawings, substantially identical to those in the '893 and '194 patents, prove that Honeywell’s invention was ready for patenting prior to the critical date. Honeywell disagrees. Its expert, Mr. Muller, testified that the drawings relied upon by Sundstrand would not allow “any engineer that [he] kn[ew] of with any amount of experience, to simply take [those drawings] and go off and design a surge control system” because “the details and the operation of the figures themselves are of little or no use in being able to discern how the system operates.” (J.A. at 16613-14.) The jury was entitled to resolve the conflicting evidence in favor of Honeywell, Bio-Tech. Gen. Corp. v. Genentech, Inc., 267 F.3d 1325, 1330-31 (Fed.Cir.2001), particularly given the heavy burden to establish invalidity by clear and convincing evidence. Thus, we agree with the district court that substantial evidence supports the jury’s verdict that the claimed invention was not ready for patenting prior to the critical date and not invalid under the on-sale bar.⁹

The jury’s findings that the '893 and '194 patents are not anticipated or obvious are also supported by substantial evidence. On the issue of anticipation, Sundstrand argues that one reference in particular, the Warnoek article, anticipates all of the asserted claims. Not surprisingly, the expert testimony presented at trial took opposing views on whether the War-nock article disclosed a system capable of maintaining an essentially constant minimum flow rate, as the claims require. In view of this evidence, we agree with the district court that there was substantial evidence to support the jury’s finding of no anticipation. Sundstrand contends that, even if not anticipating, the prior art renders claims 8, 10, and 11 of the '893 patent obvious. However Honeywell’s expert, Mr. Muller, testified that the patented invention differs in both function and structure from that described by the prior art. He testified that the prior art did not “have a proportional and integral controller, but only ... a proportional controller” and that as a result the prior art “var[ied] the flow in order to get away from surge” whereas the patented invention was able to “maintain a constant flow.” (J.A. at 16,612.) Evidence of commercial success and copying was also introduced. In light of this evidence, we again agree with the district court that there is substantial evidence to support the jury’s finding of non-obviousness. We further conclude that the district court did not abuse its discretion in denying Sundstrand’s motion for a new trial on any of the asserted grounds for invalidity.

CONCLUSION

For the foregoing reasons, we conclude that the amendments made during prosecution give rise to a presumptive surrender of equivalents for the inlet guide vane limitation. Consequently, we vacate the judgment of infringement under the doctrine of equivalents and remand to the district court to consider whether Honeywell can rebut that presumption under the Festo criteria. We affirm the district court’s judgment that the asserted claims of the '893 and '194 patents are not invalid. Because the judgment on liability has been vacated, we do not reach Sundst-rand’s argument regarding the sufficiency of evidence supporting the verdict of infringement, nor do we reach Honeywell’s arguments on damages.

AFFIRMED-IN-PART, VACATED-IN-PART, AND REMANDED.

COSTS

Each party shall bear its own costs.

1 . The DELPQP value used in the accused device has an unusual characteristic. In most airflow conditions the value of DELPQP is directly proportional to the amount of airflow. At high levels of flow, however, DELPQP becomes inversely proportional to the amount of flow, i.e., above a certain level of flow DELPQP decreases instead of increases as flow increases. Reliance upon DELPQP under these conditions might incorrectly characterize a safe high flow situation as an unsafe low flow situation, resulting in the surge bleed valve being opened to increase flow unnecessarily, causing excess APU fuel consumption.

2 . "Inlet guide vane limitation” here refers to both the claimed structure of the inlet guide vanes and their claimed function in the surge control system (e.g., "varying said set point as a function of the position of said inlet guide vanes,” '893 patent, claim 8, and "adjusting the relationship between the magnitudes of said ... control signals and ... said parameter variations as a function of the position of the inlet guide vanes,” '194 patent, claim 4).

3 . The district court construed step (d) to mean "the relationship between the magnitudes of the control signals and the magnitudes of the parameter variations, and that relationship is adjusted as a function of the position of the inlet guide vanes.” Honeywell Int'l Inc. v. Hamilton Sunstrand Corp., No. 99-309 GMS, slip op. at 2, 2001 WL 34030812 (D.Del. Feb. 16, 2001).

4 . Claims 17 and 35 of the '893 patent application and claim 51 of the '194 patent application provided:

17. The accessory power unit of Claim 16 wherein said compressor has adjustable inlet guide vanes, the value of said flow-related parameter is substantially independent of the temperature of the compressed air, said comparator means have an adjustable control set point representing said desired value of said parameter, and said accessory power unit further comprises means for transmitting to said comparator a reset signal for varying said set point as a function of the position of said inlet guide vanes in accordance with a predetermined reset schedule.

35. The control system of Claim 32 wherein the compressor has adjustable inlet guide vanes, and said control system further comprises a guide vane position sensor and a function generator coupled in series between the inlet guide vanes and said input portion of said comparator.

51. The method of Claim 49 wherein the compressor has adjustable inlet guide vanes, and said method further comprises the step of adjusting the relationship between the magnitudes of said integral and proportional control signals and the magnitudes of said parameter variations as a function of the position of the inlet guide vanes.

(App. at 18640, 18645, 18730.)

5 .Claim 35 was also rejected as indefinite under 35 U.S.C. § 112. This rejection was overcome by amendment to other claim limitations. Sundstrand does not argue that these other limitations are a basis for overruling the district court’s judgment.

6 . Although the district court's judgment did not expressly dispose of Sundstrand's counter-claims, the special verdict referred to in the court's final judgment specifically rejects each of Sundstrand’s invalidity arguments. Since the district court's intent was clear, we interpret the judgment to be a final rejection of the counterclaims for invalidity. See Pandrol USA, LP v. Airboss Ry. Prods., Inc., 320 F.3d 1354, 1362-63 (Fed.Cir.2003); Enzo Biochem, Inc. v. Calgene, Inc., 188 F.3d 1362, 1378 (Fed.Cir.1999).

7 . The government argued that:

Patent applicants may amend their patent claims for reasons of patentability — such as to clarify an ambiguous term — that do not result in narrowing the claims and surrendering subject matter. Rather, the amendments may state the same — or broader— patent claims in more precise terms. For example, an applicant may amend by rewriting a dependent claim as an independent claim. See Honeywell Int’l Inc. v. Hamilton Sundstrand Corp., No. Civ. A. 99-309 GMS, 2001 WL 66348, at *6 (D.Del. Jan.8, 2001).... Such amendments do not give rise to prosecution history estoppel, which has as its core functions preserving the notice function of the claims and preventing patent holders from recapturing under the doctrine of equivalents subject matter that was surrendered before the Patent Office. Br. for the United States as Amicus Curiae at 16-17, Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 122 S.Ct. 1831, 152 L.Ed.2d 944 (2002) (No. 00-1543) (emphases added and internal quotation marks omitted).

8 . See also Keith v. Charles E. Hires Co., 116 F.2d 46 (2d Cir.1940). In Keith, Judge Learned Hand, writing for the court, stated:

We can see no difference between that situation [where the claim was amended to secure allowance] and one where as here the applicant files a limited and a broader claim at the same time and then cancels the broader one when it has been rejected. The theory of the "estoppel,” as it is called is that, by assenting to the cancellation of the claim and by amending it, the applicant has abandoned it as it stood. Certainly it cannot be necessary to this conclusion that he shall amend the cancelled claim, when he has already filed a claim which contains the necessary differentia.

Id. at 48.

9 . Because we find that substantial evidence supports the jury’s finding that the invention was not ready for patenting prior to the critical date, we do not decide whether the agreement and subsequent papers constituted an offer to sell.