The Johns Hopkins University, Baxter Healthcare Corporation and Becton Dickinson and Company v. Cellpro, Inc.

CellPro, Inc. appeals from the decision of the United States District Court for the District of Delaware in favor of Johns Hopkins University, Baxter Healthcare Corporation, and Becton Dickinson and Company (collectively, Hopkins) in their patent infringement suit against CellPro. The court (1) granted Hopkins’ motion for judgment as a matter of law that CellPro infringed claims 1-5 of U.S. Patent B1 4,714,680, see Johns Hopkins Univ. v. CellPro, 931 F.Supp. 303, 319 (D.Del.1996) [hereinafter Hopkins /]; (2) excluded certain evidence allegedly relevant to the obviousness of those claims, see Johns Hopkins Univ. v. Cellpro, Civ. No. 94-105-RRM (D.Del. Oct. 1, 1996); id. (D.Del. Jan. 29, 1997); (3) granted Hopkins’ motion for summary judgment that CellPro infringed claims 1 and 4 of U.S. Patent 4,965,204, see id. (D.Del. Nov. 27, 1996); (4) granted Hopkins’ summary judgment motion concerning CellPro’s enablement and written description defenses, see id. (D.Del. Feb. 24, 1997) (enablement); id. (D.Del. Oct. 31, 1996) (written description); (5) sustained the jury’s verdict of willful infringement and treble damages, see Johns Hopkins Univ. v. CellPro, 978 F.Supp. 184 (D.Del.1997) [hereinafter Hopkins II ]; and (6) ordered certain vials of CellPro’s product to be repatriated to the United States and destroyed, see Johns Hopkins Univ. v. CellPro, Civ. No. 94-105-RRM (D.Del. Jul. 24, 1997). We affirm-in-part, vacate-in-part, and remand.

BACKGROUND

A. The Technology

The ’680 and ’204 patents (the “Civin patents”) issued from continuations of the same parent application 1 and pertain generally to relatively pure suspensions of immature blood cells and monoclonal antibodies used to produce such suspensions. These immature cells, known as “stem” cells, develop into many different forms of mature blood cells, including lymphoid cells (T-cells and B-cells) and myeloid cells (red cells, platelets and granulocytes). See generally Hopkins I, 931 F.Supp. at 308 (discussing the physiology of blood).

Because stem cells are killed by radiation therapy, these cells must be replaced in leukemia patients who have undergone this treatment. While bone marrow transplants can provide a patient with new stem cells, this procedure carries risks. Notably, the presence of mature cells in transplanted bone marrow can give rise to Graft Versus Host Disease (GVHD), a potentially fatal condition. 2 Accordingly, one of the stated objec *1347 tives of the invention of the Civin patents “is to provide a method for preparing a cell population useful for stem cell transplantation that is enriched in immature marrow cells and substantially free of mature myeloid and lymphoid cells.” ’680 patent, col. 2, Il. 1-5; see also Hopkins I, 931 F.Supp. at 309.

In the early 1980s, scientists began making monoclonal antibodies 3 that would recognize and bind to the antigens contained on the surface of blood cells. Once an antibody binds to an antigen on a cell surface, that cell is flagged and can be separated from other cells using known techniques such as the “FACS” method. 4 Monoclonal antibodies, which are uniform in their binding properties, are produced by cloned cells known as hybridomas. 5 Hybridomas grow and reproduce rapidly and can be frozen for later use to produce additional monoclonal antibodies.

Dr. Curt Civin, the inventor named in the ’680 and ’204 patents, discovered an antigen, which he named My-10, that appears on the surface of immature stem cells but not on the surface of mature cells. 6 The patents’ specifications disclose a monoclonal antibody, which Civin named anti-My-10, which recognizes the My-10 antigen and is useful in separating stem cells from mature cells. The patents further disclose how a hybridoma which manufactures the anti-My-10 antibody can be produced and note that a sample of the hybridoma has been deposited with the American Type Culture Collection (ATCC), ATCC Accession No. HB-8483, in Rockville, Maryland.

The ’680 and ’204 patents claim, respectively, a purified cell suspension of stem cells and monoclonal antibodies useful in producing such a suspension. The parties do not draw distinctions between the various claims in the patents, and instead premise their arguments as to each patent solely on independent claim 1 of each patent. These claims are set forth below with the disputed limitations from each claim emphasized:

’680 Claim 1: “A suspension of human cells comprising pluripotent lympho-hema-poietie stem cells substantially free of mature lymphoid and myeloid cells.”

’204 Claim 1: “A monoclonal antibody which specifically binds to an antigen on nonmalignant, immature human marrow cells, wherein said antigen is stage specific and not lineage depen- ■ dent, and soid antigen is also specifically bound by the antibody produced by the hybridoma deposited under ATCC Accession No. HB-8Í8S- ■ • - ” 7

B. CellPro’s Activities and Accused Products

1. CellPro’s Technology

Four years after the filing date of the parent application of the Civin patents, Dr. *1348 Ronald Berenson, a scientist at the Fred Hutchinson Research Center, developed a method of physically separating stem cells from mature cells that was similar to that disclosed in the Civin patents. The monoclonal antibody developed by Berenson for this purpose was designated the 12.8 antibody. 8

Berenson and others at Hutchinson formed CellPro in 1989 and obtained licenses from Hutchinson for the use of Berenson’s cell separation technology. In July 1990, CellPro produced, by cloning, a master cell bank constituting 100 vials of 12.8 hybridoma. Some of these vials were subsequently thawed and cloned to create a working cell bank to produce the 12.8 antibody. CellPro began to sell two machines, the Ceprate LC and the Ceprate SC, which its customers used in conjunction with the 12.8 antibody to perform Berenson’s cell separation method.

2. CellPro’s Knowledge of the Civin Patents and its Procurement of Legal Opinions

At the time CellPro was formed, representatives of CellPro knew of the ’680 cell suspension patent, which issued on December 12, 1987. They had also monitored the Official Gazette of the Patent and Trademark Office to determine if Civin had been issued any antibody-related patent; the ’204 antibody patent, which issued on October 23, 1990, was so discovered. See Hopkins II, 978 F.Supp. at 187-88. CellPro does not in fact dispute that it was aware of the existence of the Civin patents when it began its allegedly infringing activity.

Ostensibly concerned that CellPro’s activities might fall within the scope of the ’680 patent, Thomas Kiley, a member of CellPro’s Board of Directors and the company’s legal advisor, engaged the law firm of Lyon & Lyon LLP and its partner Coe Bloomberg in early April 1989 to provide an opinion on the validity of the claims of the ’680 patent. Bloomberg apparently reported to the Cell-Pro board in May and September 1989 that he had reviewed the prosecution history of the patent and had concluded that the patent was invalid. Bloomberg’s oral opinion was first reduced to writing on February 27, 1990. That later written opinion concluded that the claims of the ’680 patent were invalid over several pieces of prior art and were unenforceable for inequitable conduct. Cell-Pro used Bloomberg’s opinion letter to assist it in raising an additional $7.5 million from investors. See id.

In the spring of 1991, CellPro’s board asked Bloomberg for an opinion concerning the ’204 patent. Bloomberg apparently prepared a draft opinion and submitted it to Kiley, who reviewed it and provided Bloom-berg with comments. This opinion, like the ’680 opinion, concluded that the claims were invalid and unenforceable. Bloomberg also opined that CellPro did not infringe claims 2, 3, 5, and 6, but was silent as to infringement of claims 1 and 4, the claims asserted in this action. The ’204 opinion letter was also used by CellPro as a mechanism for inducing investment in the company. In the prospectus accompanying CellPro’s public offering, the company reported that “[bjased on the advice of Lyon & Lyon, special patent counsel to the company, Cell-Pro believes that [the Civin] patents are invalid and unenforceable.” Id. at 189 (internal quotations omitted).

By December of 1991, CellPro had set aside $3 million as a reserve for potential litigation involving the Civin patents. Cell-Pro also made provision in its financial forecasts for the possibility that it would litigate and lose, and be forced to pay a “stiff royalty” of 15% as damages. Id.

C. The District Court Litigation

1. Infringement

Hopkins, assignee of the Civin patents, and its licensees, Baxter Healthcare and Becton *1349 Dickinson, sued CellPro on March 8, 1994, alleging infringement of certain claims of the ’204 patent. CellPro, inter alia, counterclaimed for a declaratory judgment of invalidity and noninfringement of certain claims of the ’680 patent, prompting Hopkins to sue CellPro for infringement of that patent as well. 9

The case was tried to a jury beginning on July 24, 1995. The district court reserved construing the claims until after the presentation of evidence. At that time, the court considered but did not provide the jury with instruction concerning the meaning of the disputed limitations, concluding that the language contained therein could be understood according to its ordinary meaning. See Johns Hopkins Univ. v. CellPro, 894 F.Supp. 819, 827-28 (D.Del.1995). The jury returned a verdict entirely favorable to CellPro, concluding that all of the asserted claims of both patents were invalid for obviousness and lack of enablement, and that none of the asserted claims was infringed. See Hopkins I, 931 F.Supp. at 807.

Hopkins brought a renewed motion for judgment as a matter of law and in the alternative moved for a new trial, asserting, inter alia, that the court had erred in its construction of the disputed claim limitations. The court agreed that its failure to construe the disputed limitations appeared to be in error, see id. at 313, 317, and revisited these and other questions in considering the motion.

a. The ’680 Patent

As to the “substantially free” limitation of the ’680 claims, the district court, in considering the motion, was “reluctant to impose mathematical certainty on an ambiguous term when [the] patent applicant has strenuously avoided doing so.” Id. at 318. However, despite this reluctance, the court adopted a construction that required “a cell suspension of at least 90% purity”; in other words, “the cell suspension must contain no more than 10% mature lymphoid and myeloid cells” in order to be within the scope of the claims. Id. The court noted that its construction was consistent with the patent’s specification and with expert testimony offered at trial. The court observed that while the specification did not explicitly define the meaning of the words “substantially free,” the specification did acknowledge that the techniques used to assess the purity of My-10-positive populations “have not detected any appreciable number (i.e., not significantly above background) of normal mature ... cells.” ’680 patent, col. 3, 11. 64-67. The court, however, found persuasive Civin’s deposition testimony that one of ordinary skill would interpret the words “substantially free” in accordance with the limitations of the disclosed FACS cell separation technique which was capable of producing cell suspensions of 85-90% purity. Finally, the court noted that its construction was consistent with the patent’s disclosure of the production of a stem cell suspension of 90% purity in Table 9. 10 See Hopkins I, 931 F.Supp. at 318.

Following its first real construction of the words “substantially free,” the court granted Hopkins’ motion for judgment as a matter of law on the issue of literal infringement. The court noted that Hopkins could prove' infringement without testing the accused cell suspensions, see id. at 319 (citing Allen Archery, Inc. v. Browning Mfg. Co., 819 F.2d 1087, 1098, 2 USPQ2d 1490, 1498 (Fed.Cir.1987)), and it summarized the documentary evidence that showed that the cell suspen *1350 sions produced by CellPro’s cell separation technique were of greater than 90% purity. This evidence included a CellPro letter and brochure that explained that CellPro’s Cep-rate LC device had “achieved purities of 91.5%, 91.6%, and 98.7% during experimental runs of the device.” Id. Additionally, a clinical study protocol stated that clinicians had “achieved up to 95% purity during experiments with the Ceprate SC.” Id. The court concluded1 that, in light of this evidence, no reasonable jury could conclude that CellPro did not infringe the asserted claims of the ’680 patent. Id.

The court also granted Hopkins’ motion for a new trial on the issue of the obviousness of the asserted claims of the ’680 patent, see id. at 321; 35 U.S.C. § 103 (1994), because, inter alia, the three references upon which Cell-Pro relied to establish obviousness (viz., Civ-in, Koeffler, and Amato) were not listed on CellPro’s pre-trial order and therefore were not properly before the jury. See Hopkins I, 931 F.Supp. at 320. In its subsequent preparation for the new trial on this issue, CellPro attempted to include evidence showing that the claims as finally construed were either anticipated or obvious in light of a publication by Morstyn. 11 The court, however, ruled from the bench that it would not entertain any arguments concerning the Morstyn reference because such arguments were “based on ... prior art that [CellPro] knew about before the prior trial” but failed to then rely upon. See Johns Hopkins Univ. v. CellPro, Civ. No. 94-105-RRM (D.Del. Oct. 1, 1996) (transcript at 24). 12 The court subsequently granted summary judgment of nonobviousness to Hopkins, concluding that CellPro had failed to raise a genuine issue of material fact that warranted a trial on this issue. See Johns Hopkins Univ. v. CellPro, Civ. No. 94-105-RRM (D.Del. Jan. 29, 1997).

b. The ’WJp Patent

The district court agreed with Hopkins that the “wherein” clause of the ’204 claims referred to an antigen that was now more simply understood by those of ordinary skill in the field as the “CD34 antigen,” 13 and adopted a claim construction that reflected this understanding. Hopkins I, 931 F.Supp. at 314. The court noted that its construction was “unorthodox” because it “defined a large number of words in the claim with reference to a single alphanumeric reference, CD34,” but that this shorthand was warranted in light of the “difficulty of describing the antigen to which the ’204 patent refers.” Id. at 313. In rejecting CellPro’s argument that the court’s claim construction should not refer to CD34, but instead My-10, the antigen disclosed in the patent’s specification, the court noted that:

Those skilled in the art of making monoclonal antibodies, however, clearly under *1351 stand that My-10 and CD34 are the same. The attorney prosecuting the application for the ’204 patent argued that My-10 was becoming known in the art as CD34 as a result of the International Leukocyte Workshops. The examiner recognized this when she observed that claim 1 “limits the claimed monoclonal antibodies to species that react with a particular antigen (now identified as CD-34).”

Id. at 314. Accordingly, the court concluded that the “wherein” clause was an “attempt to describe a specific physical entity, which those skilled in the art now call the CD34 antigen,” and furthermore that any antibody which binds to this antigen would infringe the asserted claims. Id.

In light of this construction, the court granted Hopkins’ motion for a new trial on the issue of literal infringement. The court concluded that “[t]he evidence offered at trial, including [that] through CellPro’s own experts, establishes that the 12.8 antibody binds to the CD34 antigen.” Id. at 316. Rather than grant Hopkins’ renewed motion for judgment as a matter of law, the court at first allowed CellPro to attempt to establish a foundation to support its theories of nonin-fringement, which mostly hinged upon proof that the 12.8 antibodies bind to mature baso-phils. See id. at 316, 317. However, the court soon thereafter granted Hopkins’ motion for summary judgment on the issue of literal infringement, essentially concluding that the evidence that the 12.8 antibody binds to different species was irrelevant given that it binds to the CD34 antigen. See Johns Hopkins Univ. v. CellPro, Civ. No. 94-105-RRM (D.Del. Nov. 27, 1996).

The court also granted Hopkins’ motion for a new trial concerning lack of enablement of the claims of the ’204 patent. See Hopkins I, 931 F.Supp. at 322; 35 U.S.C. § 112, ¶ 1 (1994). In support of its defense, CellPro had argued that the specification does not teach one skilled in the art to make antibodies which bind to the CD34 antigen other than the disclosed anti-My-10 antibody, and accordingly that the full breadth of the asserted claims was not enabled. The court disagreed and concluded that:

the weight of the evidence suggests that the ’204 patent is enabled. Despite the fact that CellPro’s experts claim that the ’204 patent i[s] not enabling, none of them can identify anything that is missing from the specification. By contrast, the specification states that Civin’s' hybridoma is on deposit for others to utilize. In addition, the specification describes the entire fusion process, including' the immuno-gen, which is also on deposit, the specific type of mice immunized, and the use of the methodology utilized by Kohler and Mil-stein. [ 14 ]

Hopkins I, 931 F.Supp. at 324. Hopkins subsequently moved for summary judgment. See Johns Hopkins Univ. v. CellPro, Civ. No. 94-105-RRM (D.Del. Feb. 24, 1997). To rebut Hopkins’ motion, CellPro offered evidence purporting to show that various experts either could not produce another antibody using the teachings of the patent or otherwise could do so only through undue experimentation. See id.; Hybritech, Inc. v. Monoclonal Antibodies, Inc., 802 F.2d 1367, 1384, 231 USPQ 81, 94 (Fed.Cir.1986) (noting that enablement “is not precluded even if some experimentation is necessary, although the amount of experimentation needed must not be unduly excessive.”). The court did *1352 not find that CellPro’s evidence raised any genuine issue of material fact, and granted Hopkins’ summary judgment motion. The court concluded that those “experts” to whom CellPro referred in support of its argument either were not experts, did not follow the teachings of the patent, or otherwise did not engage in undue experimentation. As to those experts that only had success in producing a suitable antibody after several attempts, the court concluded that “[rjoutine repetition of a patent’s specification to achieve a desired experimental result does not constitute undue experimentation.” Johns Hopkins Univ. v. CellPro, Civ. No. 94-105-RRM, at 5 (D.Del. Feb. 24, 1997) (citing PPG Indus., Inc. v. Guardian Indus. Corp., 75 F.3d 1558, 1564, 37 USPQ2d 1618, 1623-24 (Fed.Cir.1996)).

CellPro further argued in the district court that the asserted claims of the ’204 patent were invalid for failure to satisfy the written description requirement of 35 U.S.C. § 112, ¶ 1 (1994). The court, from the bench, granted CellPro permission to assert this defense, but then granted summary judgment to Hopkins’ on the merits. See Johns Hopkins Univ. v. CellPro, Civ. No. 94-105-RRM (D.Del. Oct. 31, 1996) (transcript at 12-13).

2. Damages and Willful Infringement

With CellPro’s liability for infringement decided by the grant of Hopkins’ various motions, the issues of damages and willful infringement were tried to a jury beginning March 4, 1997. See Hopkins II, 978 F.Supp. at 186. The jury assessed over $2.3 million dollars in damages and found CellPro’s infringement to be willful. See id. at 191-92. Hopkins then moved for enhanced damages pursuant to 35 U.S.C. § 284. 15 The court, noting that enhanced damages under section 284 are punitive in nature, see, e.g., Beatrice Foods Co. v. New England Printing & Lithographing Co., 923 F.2d 1576, 1580, 17 USPQ2d 1553, 1556 (Fed.Cir.1991), applied the factors enumerated in Read Corp. v. Portec, Inc., 970 F.2d 816, 827, 23 USPQ2d 1426, 1435-36 (Fed.Cir.1992), to determine the extent to which enhancement was appro-. priate. 16 Central to the court’s decision to treble damages, the maximum enhancement permissible under the statute, was its conclusion that Bloomberg’s opinion letters were:

so obviously deficient, one might expect a juror to conclude that the only value they had to CellPro in the world outside the courtroom would have been to file them in ' a drawer until they could be used in a cynical effort to try and confuse or mislead what CellPro, its Board, and counsel must have expected would be an unsophisticated jury.

Hopkins II, 978 F.Supp. at 193. The district court was not convinced that the opinion letters provided CellPro with a good faith belief that the patents were invalid. See note 16, supra (second factor). Specifically, the court found the opinions to be untimely, not competent, and not relied upon by CellPro. See Hopkins II, 978 F.Supp. at 193.

• 3. The Repatriation Order

As part of the district court’s permanent injunction order, Johns Hopkins Univ. v. CellPro, Civ. No. 94-105-RRM (D.Del. Jul. 24, 1997), the court ordered CellPro to repatriate to the United States “all clones or subclones of the 12.8 hybridoma cell line previously exported by it, as well as any further clones or subclones produced therefrom,” and any antibodies produced there *1353 from. Id. at 3-4. This order encompassed six vials of 12.8 hybridoma from CellPro’s United States cell bank which CellPro sent to its Canadian business partner, Biomira, Inc., and cloned vials and antibodies produced therefrom in Canada. These six vials, like the other vials in the cell bank, were created prior to the issuance of the ’204 patent, the only patent that is relevant to the 12.8 hybri-doma, but were sent to Canada during the term of that patent. The six vials were never thawed or used in any manner prior to their export. One of the six vials was cloned in Canada to produce a working Canadian cell bank of 32 vials of 12.8 hybridoma. Under CellPro’s contract with Biomira, Biomira thawed and used the hybridoma from the Canadian cell bank to make 12.8 antibodies for the performance of the Berenson cell separation technique in Canada. Title to the hybridoma, however, remained with CellPro.

In its memorandum opinion supporting its repatriation order, the court did not find compelling CellPro’s argument that none of its activities concerning the six vials exported to Canada were infringing uses under 35 U.S.C. § 271 and that they were thus free of the court’s equitable power to order repatriation:

CellPro argues that because it shipped cells that were part of the original batch of noninfringing cells — rather than those that were cloned [after the issuance of the ’204 patent in the United States] — it did not run afoul of § 271(a). The court finds this distinction to be immaterial. CellPro created the 12.8 hybridoma with the intention of developing a bank of identical cells to produce a monoclonal antibody — the 12.8 antibody. Thus, by using some cells in the [United States cell] bank for the purpose of cloning or testing, it is committing an infringing “use” with respect to the bank as a whole.

Accordingly, because CellPro created and maintained its hybridoma in Canada as a result of infringing activities in the United States, the court finds that it will be acting within its equitable powers under 35 U.S.C. § 283 by ordering CellPro to repatriate the hybridomas stored at Biomira. Doing so would tend to reestablish the status quo as it existed before CellPro willfully infringed the asserted claims of the ’204 patent.

Id. at 27 (memorandum opinion).

CellPro appealed numerous points of error to this court. We have jurisdiction pursuant to 28 U.S.C. § 1295(a)(1) (1994).

DISCUSSION

A. Standard of Review

Judgment as a matter of law (JMOL) is appropriate when “a party has been fully heard on an issue and there is no legally sufficient evidentiary basis for a reasonable jury to find for that party on that issue.” Fed.R.Civ.P. 50(a)(1). We review a district court’s decision on a motion for JMOL de novo, reapplying the JMOL standard. See Markman v. Westview Instruments, Inc., 52 F.3d 967, 975, 34 USPQ2d 1321, 1326 (Fed.Cir.1995) (in banc), aff'd, 517 U.S. 370, 116 S.Ct. 1384, 134 L.Ed.2d 577, 38 USPQ2d 1461 (1996). Summary judgment is appropriate when there are no genuine issues of material fact and the moving party is entitled to judgment as a matter of law. Fed.R.Civ.P. 56(c). We similarly review a district court’s grant of summary judgment de novo, reapplying the summary judgment standard. See Conroy v. Reebok Int'l, Ltd., 14 F.3d 1570, 1575, 29 USPQ2d 1373, 1377 (Fed.Cir.1994).

“[T]he determination whether a claim has been infringed requires a two-step analysis: First, the claim must be properly construed to determine its scope and meaning. Second, the claim as properly construed must be compared to the accused device or process.” Carroll Touch, Inc. v. Electro Mechanical Sys., Inc., 15 F.3d 1573, 1576, 27 USPQ2d 1836, 1839 (Fed.Cir.1993). The first step, claim construction, is a question of law, which we review de novo. See Cybor Corp. v. FAS Techs., Inc., 138 F.3d 1448, 1456, 46 USPQ2d 1169, 1174 (Fed.Cir.1998) *1354 (in banc). The second step is factual. See North Am. Vaccine, Inc. v. American Cyanamid Co., 7 F.3d 1571, 1574, 28 USPQ2d 1333, 1335 (Fed.Cir.1993). When construing a claim, a court principally consults the evidence intrinsic to the patent, viz., the claims themselves, the written description portion of the specification, and the prosecution history. See Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582-83, 39 USPQ2d 1573, 1576-77 (Fed.Cir.1996). Whether making and using an invention would have required undue experimentation, and thus whether a disclosure is enabling under 35 U.S.C. § 112, ¶ 1 (1994), is a legal conclusion based upon underlying factual inquiries. See In re Wands, 858 F.2d 731, 735, 736-37, 8 USPQ2d 1400, 1402, 1404 (Fed.Cir.1988).

Because courts have broad discretion in determining the scope of injunctive relief under 35 U.S.C. § 283 (1994), we review the scope of a district court’s permanent injunction for an abuse of discretion. See Ortho Pharm. Corp. v. Smith, 959 F.2d 936, 945, 22 USPQ2d 1119, 1127 (Fed.Cir.1992). Likewise, the propriety of an evidentiary ruling by the district court is reviewed for an abuse of discretion. See Kearns v. Chrysler Corp., 32 F.3d 1541, 1547, 31 USPQ2d 1746, 1750 (Fed.Cir.1994); In re Merritt Logan, 901 F.2d 349, 359 (3rd Cir.1990).

Whether infringement was willful is a question of fact, and we will not reverse a jury determination on this issue unless it was unsupported by substantial evidence. See Hoechst Celanese Corp. v. BP Chems. Ltd., 78 F.3d 1575, 1583, 38 USPQ2d 1126, 1132 (Fed.Cir.1996). A district court’s decision to enhance damages for willful infringement and the extent of the enhancement is reviewed for an abuse of discretion. See SRI Int’l, Inc. v. Advanced Tech. Labs., Inc., 127 F.3d 1462, 1468, 44 USPQ2d 1422, 1427 (Fed.Cir.1997).

B. Validity and Infringement of the ’680 Patent

1. Claim Construction and Infringement

CellPro asserts that the district court’s construction of the “substantially free” limitation to require no more than 10% mature cells was in error. Instead CellPro believes that this limitation should be construed to mean an immeasurable amount of mature cells. Accordingly, CellPro contends that JMOL of infringement was erroneously granted, because cell suspensions produced by its technique and equipment contained measurable amounts of mature cells numbering in the “millions.”

To support its claim construction, CellPro points to the prosecution history of the ’680 patent, which progressed in relevant part as follows: The examiner rejected the claims as anticipated by two prior art publications by Bodger et al. The applicant responded by noting that Bodger’s antibodies could not be used to produce a cell suspension that was “substantially free” of mature cells as required by the claim language. The examiner was not persuaded and noted that “[t]he metes and bounds of ‘substantially free’ have not been established” by the applicant, to which the applicant responded:

“Substantially free” is defined by its plain meaning and further by the stated characteristics of the anti-My-10 antibody_ At page 5, lines 27-31, of the specification [see ’680 patent, col. 6, 11. 62-67] it is explicitly stated, “Various assay techniques have been employed to test for the presence of the My-10 antigen, and those techniques have not detected any appreciable number (i.e., not significantly above background) of normal, mature human myeloid and lymphoid cells in My-10-positive populations.” For example, when My-10 + cells are incubated with a series of monoclonal antibodies which react with T-lymphocytes [i.e., a type of mature cell], no cells are found to be reactive. Thus, by the means presently available to the art, no T-lymphocytes are found in My-10 + cell populations.

*1355 (emphasis in original). 17 The applicant also noted that “Bodger’s cell population has some T-eells present, but [that] the present invention has none,” and therefore that Bodger’s cell suspension would be ineffective in preventing GVHD.

Hopkins responds that the district court’s claim construction was correct and was consistent with the intrinsic evidence. Hopkins notes that the specification, reflecting the imperfect state of the art and specifically the imperfect nature of cell separation techniques such as the FACS method, teaches that the disclosure concerning preparation of antibodies would enable the creation of only “relatively pure” stem cell suspensions. See ’680 patent, col. 4, 11. 55. Hopkins asserts that the highest disclosed purity for a stem cell suspension created by the disclosed technique, viz. 90%, see ’680 patent, col. 18, tbl. 9, should define the outer bounds of the words “substantially free.” Hopkins argues that CellPro’s proposed claim construction and citation from the prosecution history are inconsistent with Table 9, which describes small but measurable amounts of mature cells.

We agree with Hopkins that the district court’s construction of the words “substantially free” was not in error. Table 9, the only disclosed embodiment of the claimed cell suspension, 18 is highly indicative of the scope of the claims. A patent claim should be construed to encompass at least one disclosed embodiment in the written description portion of the patent specification. This maxim flows from the statutory requirement that “[t]he specification shall contain a written description of the invention,” 35 U.S.C. § 112, ¶ 1 (1994), which requires a patent applicant to disclose in the specification sufficient subject matter to support the breadth of his claim. See Specialty Composites v. Cabot Corp., 845 F.2d 981, 987, 6 USPQ2d 1601, 1604 (Fed.Cir.1988) (noting that what is patented “is defined by the words in the claims if those claims are supported by the specification in the manner required by 35 U.S.C. § 112.”); Pall Corp. v. Micron Separations, Inc., 66 F.3d 1211, 1219, 36 USPQ2d 1225, 1230-31 (Fed.Cir.1995). A claim construction that does not encompass a disclosed embodiment is thus “rarely, if ever, correct and would require highly persuasive eviden-tiary support.” Vitronics, 90 F.3d at 1583, 39 USPQ2d at 1578. Accordingly, CellPro’s claim construction, that the cell suspension of the claims can contain only an immeasurable amount of mature cells, is undermined by Table 9 of the specification, which describes the only embodiment of the invention disclosed in the specification and discloses a cell suspension that contains 3% mature neutro-phils, 6% mature monocytes, and 1% mature lymphocytes, all of which constitute measurable quantities of mature lymphoid cells. See ’680 patent, col. 18, tbl. 9 n.*.

CellPro also notes that in response to the examiner’s request to clarify the “metes and bounds” of the words “substantially free,” the applicant, quoting the specification, noted that “[v]arious assay techniques have been employed to test for the presence of the My-10 antigen, and those techniques have not detected any appreciable number (i.e., not significantly above background) of normal, mature human myeloid and lymphoid cells in My-10-positive populations.” Howe