Court Opinion

ID: 4511901
Source: CourtListenerOpinion
Date Created: 2020-03-02 17:00:40.073661+00
Date Added: 2024-06-11T08:38:26.618123
License: Public Domain

Case: 16-2231   Document: 164    Page: 1    Filed: 03/02/2020

    United States Court of Appeals
        for the Federal Circuit
                 ______________________

           GS CLEANTECH CORPORATION,
                  Plaintiff-Appellant

                            v.

                ADKINS ENERGY LLC,
                Defendant-Cross-Appellant
                 ______________________

                  2016-2231, 2017-1838
                 ______________________

    Appeals from the United States District Court for the
 Northern District of Illinois in No. 1:10-cv-04391, Judge
 Larry J. McKinney.

 --------------------------------------------

   GS CLEANTECH CORPORATION, GREENSHIFT
               CORPORATION,
              Plaintiffs-Appellants

                CANTOR COLBURN LLP
                    Interested Party

                            v.

  BIG RIVER RESOURCES GALVA, LLC, BIG RIVER
       RESOURCES WEST BURLINGTON, LLC,
   LINCOLNLAND AGRI-ENERGY, LLC, IROQUOIS
      BIO-ENERGY COMPANY, LLC, CARDINAL
    ETHANOL, LLC, LINCOLNWAY ENERGY, LLC,
Case: 16-2231   Document: 164   Page: 2   Filed: 03/02/2020

 2                GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  ICM, INC., BUSHMILLS ETHANOL, INC., AL-CORN
       CLEAN FUEL, LLC, CHIPPEWA VALLEY
   ETHANOL COMPANY, LLP, HEARTLAND CORN
   PRODUCTS, GEA MECHANICAL EQUIPMENTUS,
     INC., AS SUCCESSOR-IN-INTEREST TO GEA
    WESTFALIA SEPARATOR, INC. PURSUANT TO
    THE NOTICE OF MERGER FILED ON 4/28/2011,
  ACE ETHANOL, LLC, BLUE FLINT ETHANOL LLC,
   UNITED WISCONSIN GRAIN PRODUCERS, LLC,
    FLOTTWEG SEPARATION TECHNOLOGY, INC.,
   ADKINS ENERGY LLC, AEMETIS, INC., AEMETIS
   ADVANCED FUELS KEYES, INC., LITTLE SIOUX
  CORN PROCESSORS, LLLP, GUARDIAN ENERGY,
      LLC, WESTERN NEW YORK ENERGY, LLC,
   SOUTHWEST IOWA RENEWABLE ENERGY, LLC,
      PACIFIC ETHANOL MAGIC VALLEY LLC,
     PACIFIC ETHANOL STOCKTON, HOMELAND
   ENERGY SOLUTIONS, LLC, PACIFIC ETHANOL,
           INC., DAVID J. VANDER GRIEND,
                   Defendants-Appellees
                  ______________________

                       2017-1832
                 ______________________

    Appeal from the United States District Court for the
 Southern District of Indiana in Nos. 1:10-cv-00180-RLM-
 DML, 1:10-cv-08000-RLM-DML, 1:10-cv-08001-RLM-
 DML, 1:10-cv-08002-RLM-DML, 1:10-cv-08003-RLM-
 DML, 1:10-cv-08004-RLM-DML, 1:10-cv-08005-RLM-
 DML, 1:10-cv-08006-RLM-DML, 1:10-cv-08007-RLM-
 DML, 1:10-cv-08008-RLM-DML, 1:10-cv-08009-RLM-
 DML, 1:10-cv-08010-RLM-DML, 1:10-cv-08011-RLM-
 DML, 1:10-ml-02181-RLM-DML, 1:13-cv-08012-RLM-
 DML, 1:13-cv-08013-RLM-DML, 1:13-cv-08014-RLM-
 DML, 1:13-cv-08015-RLM-DML, 1:13-cv-08016-RLM-
 DML, 1:13-cv-08017-RLM-DML, 1:13-cv-08018-RLM-
Case: 16-2231   Document: 164     Page: 3   Filed: 03/02/2020

 GS CLEANTECH CORP. v. ADKINS ENERGY LLC                 3

 DML, 1:14-cv-08019-RLM-DML, 1:14-cv-08020-RLM-
 DML, Judge Larry J. McKinney.
                ______________________

                  Decided: March 2, 2020
                  ______________________

     STEVEN B. POKOTILOW, Stroock & Stroock & Lavan
 LLP, New York, NY, argued for plaintiffs-appellants. Also
 represented by BINNI N. SHAH.

     JOHN M. WEYRAUCH, Dicke, Billig & Czaja, PLLC, Min-
 neapolis, MN, argued for defendants-appellees Big River
 Resources Galva, LLC, Big River Resources West Burling-
 ton, LLC, Lincolnland Agri-Energy, LLC, Cardinal Etha-
 nol, LLC, Lincolnway Energy, LLC, ICM, Inc., Flottweg
 Separation Technology, Inc., Blue Flint Ethanol, LLC, Da-
 vid J. Vander Griend. Defendants-appellees Big River Re-
 sources Galva, LLC, Big River Resources West Burlington,
 LLC, Lincolnland Agri-Energy, LLC, Cardinal Ethanol,
 LLC, ICM, Inc., Flottweg Separation Technology, Inc., Lit-
 tle Sioux Corn Processors, LLLP, Guardian Energy, LLC,
 Western New York Energy, LLC, Southwest Iowa Renew-
 able Energy, LLC, Pacific Ethanol Magic Valley LLC, Da-
 vid J. Vander Griend also represented by PETER R.
 FORREST.

    MICHAEL BUCHANAN, Patterson Belknap Webb & Tyler
 LLP, New York, NY, argued for defendants-appellees ACE
 Ethanol, LLC, Aemetis Advanced Fuels Keyes, Inc.,
 Aemetis, Inc., Al-Corn Clean Fuel, LLC, Big River Re-
 sources Galva, LLC, Big River Resources West Burlington,
 LLC, Blue Flint Ethanol LLC, Bushmills Ethanol, Inc.,
 Cardinal Ethanol, LLC, Chippewa Valley Ethanol Com-
 pany, LLP, Flottweg Separation Technology, Inc., GEA Me-
 chanical Equipment US, Inc., Guardian Energy, LLC,
 Heartland Corn Products, Homeland Energy Solutions,
 LLC, ICM, Inc., Iroquois Bio-Energy Company, LLC,
Case: 16-2231    Document: 164     Page: 4   Filed: 03/02/2020

 4                  GS CLEANTECH CORP. v. ADKINS ENERGY LLC

 Lincolnland Agri-Energy, LLC, Lincolnway Energy, LLC,
 Little Sioux Corn Processors, LLLP, Pacific Ethanol Magic
 Valley LLC, Pacific Ethanol Stockton, Pacific Ethanol, Inc.,
 Southwest Iowa Renewable Energy, LLC, United Wiscon-
 sin Grain Producers, LLC, David J. Vander Griend, West-
 ern New York Energy, LLC, Adkins Energy LLC.

     KEITH DAVID PARR, Locke Lord LLP, Chicago, IL, for
 defendant-cross-appellant. Also represented by HUGH S.
 BALSAM, WASIM K. BLEIBEL, JAMES THOMAS PETERKA.

    SPIRO BEREVESKOS, Woodard Emhardt Henry Reeves &
 Wagner, LLP, Indianapolis, IN, for defendant-appellee Ir-
 oquois Bio-Energy Company, LLC. Also represented by
 DANIEL JAMES LUEDERS, LISA A. HIDAY.

     GLENN JOHNSON, McKee, Voorhees & Sease, P.L.C.,
 Des Moines, IA, for defendant-appellee Lincolnway En-
 ergy, LLC.

     JOHN DONALD BEST, Michael Best & Friedrich, LLP,
 Madison, WI, for defendants-appellees Bushmills Ethanol,
 Inc., Chippewa Valley Ethanol Company, LLP, Heartland
 Corn Products, United Wisconsin Grain Producers, LLC.
 Also represented by KENNETH M. ALBRIDGE, III, JOHN C.
 SCHELLER.

     MARC ANDRE AL, Stoel Rives LLP, Minneapolis, MN,
 for defendant-appellee Al-Corn Clean Fuel, LLC.

     RUTH RIVARD, Stinson LLP, Minneapolis, MN, for de-
 fendant-appellee Blue Flint Ethanol LLC.

    CAMILLE L. URBAN, Brown, Winick, Graves, Gross, Bas-
 kerville & Schoenebaum, PLC, Des Moines, IA, for defend-
 ants-appellees Aemetis, Inc., Aemetis Advanced Fuels
 Keyes, Inc., Pacific Ethanol Stockton, Homeland Energy
Case: 16-2231    Document: 164     Page: 5    Filed: 03/02/2020

 GS CLEANTECH CORP. v. ADKINS ENERGY LLC                    5

 Solutions, LLC, Pacific Ethanol, Inc. Also represented by
 MICHAEL A. DEE.
                 ______________________

   Before REYNA, WALLACH, and HUGHES, Circuit Judges.
 WALLACH, Circuit Judge.
     The U.S. District Court for the Southern District of In-
 diana (“District Court”) found Appellants GS CleanTech
 Corporation and Greenshift Corporation’s (together,
 “CleanTech”) U.S. Patent Nos. 7,601,858 (“the ’858 pa-
 tent”), 8,008,516 (“the ’516 patent”), 8,008,517 (“the ’517
 patent”), and 8,283,484 (“the ’484 patent”) (together, “the
 Patents-in-Suit”) unenforceable due to inequitable con-
 duct. Corrected Memorandum Opinion & Order after
 Bench Trial, In re: Method of Processing Ethanol Byprod-
 ucts & Related Subsystems (’858) Patent Litig., No. 1:10-
 ml-02181-LJM-DML (S.D. Ind. Sept. 15, 2016), ECF
 No. 1653 (J.A. 236–313) (Opinion and Order); see J.A. 314–
 15 (Judgment).
    CleanTech appeals. We have jurisdiction pursuant to
 28 U.S.C. § 1295(a)(1) (2012). We affirm.
                        BACKGROUND
                   I. The Patents-in-Suit 1
     The Patents-in-Suit are directed to the recovery of oil
 from a dry mill ethanol plant’s byproduct, called thin stil-
 lage. ’858 patent, Abstract. 2 The Patents-in-Suit disclose

     1   The Patents-in-Suit share a specification. For the
 ease of reference here, we will refer to the ’858 patent’s
 specification.
     2   Stillage treatment relates to the process of treating
 “‘whole stillage[,]’” which is the “waste stream comprised of
 byproducts” that is a result of the dry milling process. ’858
 patent col. 1 ll. 35–41. Dry milling is “a popular method of
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 6                   GS CLEANTECH CORP. v. ADKINS ENERGY LLC

 a method of “successful” “recover[y] [of] the valuable oil
 from th[e] [thin stillage] byproduct,” id. col. 1 ll. 52–53, by,
 for example, “evaporating the thin stillage to form a con-
 centrate,” id. col. 2 ll. 23–25, or syrup, and then “separat-
 ing the oil from the concentrate using a disk stack
 centrifuge,” id. col. 2 ll. 25–27.
     Independent claim 8 of the ’858 patent recites:
     A method of recovering oil from thin stillage, compris-
     ing, in sequence: evaporating the thin stillage to create
     a concentrate having a moisture content of greater
     than 30% by weight and less than about 90% by
     weight; and centrifuging the concentrate to recover oil.
 Id. col. 6 ll. 26–30. 3 Independent claims 1, 10, and 16 in-
 clude a separate post-evaporation heating step. Id. col. 5
 l. 65–col. 6 l. 7 (Independent Claim 1), col. 6 ll. 34–42 (In-
 dependent Claim 10), col. 6 ll. 59–64 (Independent
 Claim 16). All dependent claims recite various combina-
 tions of temperature, pH, or moisture content ranges for
 the syrup or the use of the centrifuge. Id. col. 6 ll. 8–33,
 43–58. Independent claim 30 of the ’484 patent similarly
 recites a “method of recovering oil from thin stillage[,]” ex-
 cept it is by “mechanically processing the thin stillage con-
 centrate” instead of centrifugation. ’484 patent col. 8
 ll. 29–37.

 producing ethanol . . . [and] is typically practiced using
 corn.” Id. col. 1 ll. 35–37. Whole stillage, which has com-
 monly been treated as waste, “may be further separated
 into products known as distillers wet grains and ‘thin stil-
 lage.’” Id. col. 1 ll. 41–43.
     3    Independent claim 8, which is illustrative, broadly
 recites the claimed invention. The remaining claims recite
 additional limitations beyond those recited in independent
 claim 8.
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 GS CLEANTECH CORP. v. ADKINS ENERGY LLC                    7

      Independent claim 1 of the ’516 patent provides the ad-
 ditional step of “evaporating water from the thin stillage to
 form a thin stillage concentrate.” ’516 patent col. 6 ll. 11–
 19. Independent claim 7 includes the additional step of
 “separating distiller wet grains and thin stillage from the
 whole stillage” and using a disk stack centrifuge to sepa-
 rate the “oil from the thin stillage concentrate.” Id. col. 6
 ll. 34–42. Independent claim 1 of the ’517 patent also re-
 cites the creation of the thin stillage concentrate, within a
 broader moisture content range. ’517 patent col. 6 ll. 32–
 37.
                     II. Factual History 4
    A. Development of the Ethanol Oil Recovery System
     In 2000, David Cantrell founded Vortex Dehydration
 Technology (“VDT”), J.A. 117, with the purpose of selling
 products and methods of processing factory waste for re-
 sale, J.A. 118. In 2002, David Winsness joined VDT as its
 Chief Technology Officer. J.A. 117. Later in 2002, Messrs.
 Cantrell and Winsness (collectively, “the Inventors”) met
 Greg Barlage, a “market unit manager for equipment
 sales” at the company Alfa Laval AB, which sold animal
 and vegetable oil processing equipment. J.A. 117, 118.
 Mr. Barlage approached the Inventors with the proposal
 that VDT use Alfa Laval oil processing equipment—such
 as evaporators and centrifuges—in its processes. J.A. 119.
 Soon, the Inventors began developing an oil recovery prod-
 uct specifically designed for animal processing waste prod-
 ucts, using centrifuges provided by Alfa Laval. J.A. 119.
     Relevant here, VDT maintained a business relation-
 ship with Agri-Energy LLC (“Agri-Energy”), J.A. 121,
 which operated a dry-mill ethanol plant in Minnesota,

     4   We will rely on the District Court’s factual recita-
 tion where it is uncontested by the parties. Where certain
 facts are disputed, we will refer to the record evidence.
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 8                  GS CLEANTECH CORP. v. ADKINS ENERGY LLC

 J.A. 120. 5    Starting sometime before June 2003,
 Mr. Cantrell shifted his focus from meat and fish byproduct
 processing to the creation of an ethanol oil recovery system
 and hired employees from Alfa Laval and Agri-Energy, as
 well as a marketing team. J.A. 122. In June 2003,
 Mr. Cantrell sent an email to two Agri-Energy employees,
 including one named George Winter, that included infor-
 mation about how VDT’s oil recovery system for processed
 animal waste might be applicable in an ethanol plant, as
 well as an image of an oil recovery system with a centrifuge
 and an operational cost spreadsheet. J.A. 123. Subse-
 quently, Mr. Cantrell informed Mr. Barlage that Agri-En-
 ergy would send Mr. Barlage a sample of its “thin stillage

     5    The District Court discounted testimony provided
 by Mr. Cantrell at the bench trial, determining that
 Mr. Cantrell’s testimony “on any topic [to be] of little cred-
 ible value.” J.A. 242. The District Court noted that
 Mr. Cantrell made “inconsistent statements,” “had some
 difficulty staying focused,” and “was argumentative and
 unclear about facts when questioned by [Appellees’] coun-
 sel.” J.A. 242–43. The District Court stated that this was
 in sharp contrast to Mr. Cantrell’s “fortuitously remem-
 ber[ing] when events took place and recall[ing] the ‘real’
 meaning of documents when questioned by CleanTech’s
 lawyers.” J.A. 243. The District Court concluded that
 “[Mr.] Cantrell’s testimony sounded carefully scripted ra-
 ther than genuine and generally dismissive of the contem-
 poraneous documentary evidence.” J.A. 243. Accordingly,
 the District Court determined that it would “rel[y] primar-
 ily on the documents and testimony from other witnesses
 about the relationship between Agri-Energy and inventors
 during this period[.]” J.A. 243. “[We] give[] great deference
 to the district court’s decisions regarding [the] credibility
 of witnesses.” Ecolochem, Inc. v. S. Cal. Edison Co., 227
F.3d 1361, 1378–79 (Fed. Cir. 2000) (internal quotation
 marks and citation omitted).
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 GS CLEANTECH CORP. v. ADKINS ENERGY LLC                   9

 and syrup” for oil recovery testing using a centrifuge.
 J.A. 124. 6
     In June 2003, Mr. Barlage performed oil recovery tests
 on the Agri-Energy samples by heating each sample to a
 temperature of 176 ºF and running them through an Alfa
 Laval centrifuge. J.A. 125. The syrup had a pH of “approx-
 imately 4” and a “moisture content between 70% and 80%.”
 J.A. 125. Based on the tests, Mr. Barlage concluded that it
 was easier to divest oil from syrup than from thin stillage.
 J.A. 125. In his report (“June 2003 Report”), Mr. Barlage
 concluded that “[s]omething in the evaporation process al-
 lows for the product to breakdown to a level where the oil
 can be taken out easily[,]” and recommended additional
 testing at a plant. J.A. 110092.
      In early July 2003, Mr. Barlage traveled to Agri-En-
 ergy and tested VDT’s oil recovery system, including a cen-
 trifuge, with Agri-Energy’s ethanol syrup (“July 2003
 Test”). J.A. 128–29. Again, the test included a syrup with
 a pH of around 4, with a moisture content between 70% and
 80%, and the test was conducted at a temperature of
 180 ºF. J.A. 128–29. During the test, the centrifuge sepa-
 rated the oil from the syrup, but the centrifuge repeatedly
 clogged. J.A. 129. Around this time, Mr. Winsness di-
 rected a VDT employee to prepare a drawing of the ethanol
 oil recovery system, J.A. 130–31, which was completed by
 the end of July 2003, J.A. 132; see J.A. 110044 (Ethanol Oil
 Recovery System Diagram). The employee understood that
 the Ethanol Oil Recovery System Diagram “was intended
 to become a sales drawing.” J.A. 17278.
     On August 1, 2003, Mr. Cantrell emailed several Agri-
 Energy employees (“August 2003 Email”) and attached a
 proposal, dated July 31, 2003.         J.A. 132–33; see

     6   Ethanol syrup is concentrated thin stillage.
 J.A. 124.
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  10                  GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  J.A. 110021–22 (“July 2003 Proposal”). The July 2003 Pro-
  posal stated that VDT “would like to offer Agri-Energy a
  No-Risk trial [of the] ‘Oil Recovery System.’” J.A. 110021.
  The proposal stated that “[t]he test module is designed to
  process 18,000 [pounds] per hour of evaporator condensate
  and recovers 16,000 [pounds] of oil per day adding annual
  profits of $312,000 to $530,000 per year.” J.A. 110021 (em-
  phasis omitted). The proposal went on to detail the “No-
  Risk Trial,” which “allow[ed] Agri-Energy [sixty] days to
  operate the unit and confirm its value[,]” at which point
  Agri-Energy could “purchase the system” for $423,000 or
  “return the skid to [VDT] (no questions asked).”
  J.A. 110021 (emphasis omitted). According to the Inven-
  tors, the purpose of the letter was to seek an opportunity to
  run in-plant tests and obtain data on how the test module
  ran. J.A. 31418–19. Agri-Energy understood the July
  2003 Proposal as an offer for purchase. J.A. 248.
      On August 18, 2003, Mr. Cantrell traveled to Agri-En-
  ergy and, the following day, presented his proposal to the
  Agri-Energy Board of Directors. J.A. 135. In the meeting,
  Mr. Cantrell described VDT’s ethanol extraction system as
  “a process where the corn oil is pulled off[,]” and he asserted
  that the system “worked” and that it “would generate ad-
  ditional income[.]” J.A. 135–36. On the same day, Mr.
  Winsness informed VDT shareholders that Mr. Cantrell
  was “meeting with an ethanol plant” and the Inventors “ex-
  pect[ed] to have an order in the near future ($400K).”
  J.A. 136. On August 27, 2003, Mr. Cantrell informed
  VDT’s chairman that “‘we have made an offer to Agri-En-
  ergy.’” J.A. 136. Agri-Energy did not accept the July 2003
  Proposal, and no centrifuge system was installed at Agri-
  Energy’s facility at that time. J.A. 137; see J.A. 70656 (Tes-
  timony by Mr. Cantrell) (stating that Agri-Energy did not
  accept the July 2003 Proposal). In early 2004, Agri-Energy
  and VDT again communicated regarding the installation of
  an oil recovery system, J.A. 137, and in May 2004, a centri-
  fuge was installed in the Agri-Energy plant, J.A. 139.
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  GS CLEANTECH CORP. v. ADKINS ENERGY LLC                       11

                 B. Patent Prosecution History
       In February 2004, the Inventors contacted attorney
  Andrew Dorisio about preparing a patent application for,
  inter alia, their method of separating corn oil from concen-
  trated thin stillage using a centrifuge. J.A. 251–52. Spe-
  cifically, the Inventors sought to patent a method whereby
  “[a]n evaporator would be used to concentrate thin stillage”
  to a syrup with “a moisture content between 60% and 85%,”
  and the syrup would then be mechanically processed to
  separate out the oil, using a disk stack centrifuge. J.A. 251.
  The temperature and pH of the thin stillage—150 ºF to
  212 ºF and with a pH range from 3 to 6—would be the
  standard values of thin stillage in an ethanol plant.
  J.A. 251. Mr. Dorisio informed the Inventors about the on-
  sale bar of 35 U.S.C. § 102 (2000), which required that the
  claimed invention not be sold or offered for sale more than
  one year before the application filing date, and inquired if
  such an offer had been made. J.A. 252; see J.A. 111059; see
  also 35 U.S.C. § 102(b) (“A person shall be entitled to a pa-
  tent unless . . . the invention was . . . on sale . . . more than
  one year prior to the date of the application for patent in
  the United States[.]”). 7       Contemporaneous to their

      7   Congress amended 35 U.S.C. § 102 when it passed
  the Leahy-Smith America Invents Act (“AIA”), and AIA
  § 4(e) made those changes applicable to “any patent appli-
  cation that is filed on or after” September 16, 2012. Pub.
  L. No. 112-29, § 4(e), 125 Stat. 284, 297 (2011). Because
  the application that led to the Patents-in-Suit was filed be-
  fore September 16, 2012, pre-AIA § 102 applies. Under
  pre-AIA § 102, a person shall be entitled to a patent unless
  the claimed invention was on sale more than one year be-
  fore the application’s filing date. 35 U.S.C. § 102(b). A pa-
  tent is invalid under the on-sale bar if, before the filing
  date, the invention was both (1) the subject of a commercial
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  12                  GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  discussion with Mr. Dorisio, the Inventors also conducted
  research on the U.S. Patent and Trademark Office’s
  (“USPTO”) website, which included information about pro-
  visional patent applications and the on-sale bar. J.A. 252.
       Subsequently, the Inventors provided Mr. Dorisio with
  test results from June 2003 and described the July 2003
  Tests. J.A. 255. Mr. Dorisio, apparently without being told
  about the July 2003 Proposal or the Ethanol Oil Recovery
  System Diagram, filed U.S. Provisional Patent Application
  No. 60/602,050 (“the ’050 provisional application”) on Au-
  gust 17, 2004, with the USPTO, J.A. 140, 151; see J.A. 900,
  setting the critical date for the on-sale bar at August 17,
  2003, J.A. 164. See Helsinn Healthcare S.A. v. Teva
  Pharm. USA, Inc., 855 F.3d 1356, 1360 (Fed. Cir. 2017)
  (“The critical date for the on-sale bar is one year earlier[.]”),
  aff’d, 139 S. Ct. 628 (2019). In May 2005, Mr. Dorisio filed
  a non-provisional application, U.S. Patent Application
  No. 11/122,859 (“the ’859 application”). The’859 applica-
  tion included a letter stating that a separate patent appli-
  cation, entitled “Substantially Fat Free Products From
  Whole Stillage Resulting from the Production of Ethanol
  from Oil-Bearing Agricultural Products,” U.S. Patent Ap-
  plication No. 10/619,833 (“Prevost”), “may be found to claim
  the same invention as at least one claim of the instant ap-
  plication.” J.A. 256 (internal quotation marks omitted).
      In July 2005, Mr. Dorisio provided the Inventors with
  a draft clearance opinion, based on his understanding that
  the Inventors had reduced their claimed invention to prac-
  tice in June 2003, and argued that the Inventors could
  swear behind Prevost, which was filed on July 15, 2003.
  J.A. 256; see J.A. 111060–74 (Draft Clearance Opinion); see
  also J.A. 111065 (“Past correspondence indicates [the] ac-
  tual reduction to practice of the [claimed invention] during

  sale or offer for sale and (2) “ready for patenting.” See Pfaff
  v. Wells Elecs., Inc., 525 U.S. 55, 67 (1998).
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  GS CLEANTECH CORP. v. ADKINS ENERGY LLC                    13

  experiments conducted in early to mid-June 2003. If accu-
  rate, this date of invention precedes the filing date
  of . . . [Prevost] by at least one month[.]”), 18286 (Prevost)
  (providing a filing date of July 15, 2003). In 2006, the In-
  ventors joined CleanTech, J.A. 35686, which acquired
  VDT’s ethanol oil recovery method applications, J.A. 8–10. 8
      In March 2008, Mr. Winsness transferred the prosecu-
  tion of CleanTech’s ethanol oil recovery method applica-
  tions from Mr. Dorisio to the law firm Cantor Colburn LLP
  (“Cantor Colburn”). J.A. 257. An attorney at Cantor Col-
  burn, Peter Hagerty, explained to at least one of the Inven-
  tors the on-sale bar and the Inventors’ obligation of candor
  toward the USPTO. J.A. 54666. In June 2008, a USPTO
  patent examiner rejected the ’859 application, based in
  part on Prevost. J.A. 258. Cantor Colburn amended the
  ’859 application’s claims. J.A. 258. By at least Septem-
  ber 2008, Cantor Colburn was aware of Mr. Barlage’s test-
  ing in June and July 2003. J.A. 111075; see J.A. 111075
  (Mr. Winsness’s Email to Mr. Hagerty) (explaining that the
  “testing we did in June 2003” showed that “a sequence of
  evaporation followed by centrifugation allows for oil recov-
  ery”).
      In May 2009, a potential investor in CleanTech con-
  ducted due diligence and sought information on the com-
  pany’s pending patent applications; specifically, the
  potential investor requested from the Inventors “‘pre-filing
  disclosures of the inventions’” or “‘pre-filing offers for
  sale[,]’” among other information.         J.A. 261; see
  J.A. 111023. The Inventors denied having any such

      8   The ’858 patent issued from the ’859 application,
  J.A. 900, and all the remaining patents of the Patents-in-
  Suit issued from applications that were continuations of
  the ’859 application, J.A. 910, 921, 953. The Patents-in-
  Suit claim effective filing dates of August 17, 2004.
  J.A. 900, 910, 921, 953.
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  14                 GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  information, although, in 2010, “Mr. Cantrell had retained
  a ‘signed version’ of the July 2003 Proposal in his ‘home
  files,’ and ‘an unsigned version was on [Mr.] Winsness’[s]
  computer[.]’” J.A. 262; see J.A. 63882. In June 2009, Can-
  tor Colburn withdrew the pending ’859 application from is-
  sue. J.A. 264; see J.A. 71338.
       On the same day as the withdrawal, Cantor Colburn
  filed a letter with the USPTO in the ’859 application file
  disclosing that “[s]ometime in May 2004, feasibility testing
  of a process and system for recovering oil from thin stillage
  was performed[.]” J.A. 110380. The letter was also filed
  with the USPTO in the prosecution of the ’516, ’517, and
  ’484 patents. J.A. 264–65; see J.A. 110371–78, 110697–99.
  No reference was made to Mr. Barlage’s June and
  July 2003 testing, the June 2003 Report, the Ethanol Oil
  Recovery System Diagram, or the July 2003 Proposal. See
  generally J.A. 110371–74, 110375–78, 110379–81, 110697–
  99. In October 2009, the USPTO issued the ’858 patent.
  J.A. 900.
                C. The Two Cantrell Declarations
      In March 2010, Mr. Winsness provided a signed copy of
  the July 2003 Proposal to Cantor Colburn. J.A. 267; see
  J.A. 63882. 9 Around June 2010, Mr. Hagerty drafted a

       9  At trial, evidence showed that Mr. Winsness pro-
  vided Cantor Colburn with two letters in March 2010: an
  ink-signed original dated July 31, 2003, and an ink signed
  original dated August 19, 2003. J.A. 63882. The two let-
  ters differed from the electronic versions sent by
  Mr. Cantrell to Agri-Energy, such as by presenting a dif-
  ferent letterhead. J.A. 266–67. The parties presented evi-
  dence about when each letter was signed, but the District
  Court “f[ound] the results of the experts’ analyses inconclu-
  sive with respect to the dating” of the two letters. J.A. 267.
  Additionally, the District Court concluded that “[i]f it had
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  GS CLEANTECH CORP. v. ADKINS ENERGY LLC                    15

  two-page Information Disclosure Statement (“IDS”) to be
  submitted to the USPTO, attaching the July 2003 Pro-
  posal. J.A. 110793–95; see J.A. 270. In the IDS, Mr.
  Hagerty claimed that the ’858 patent’s method was “never
  disclosed, carried out, or performed” more than one year
  before the filing date and that the July 2003 Proposal was
  irrelevant. J.A. 110793–95.
      In May and June 2010, Mr. Winsness met with a com-
  pany that stated that it had reason to believe the ’858 pa-
  tent, as well as the other Patents-in-Suit, were invalid due
  to an offer in violation of the on-sale bar. J.A. 268. In late
  June 2010, Mr. Winsness made an “unannounced” trip to
  Agri-Energy and offered to provide Agri-Energy with a roy-
  alty-free license for CleanTech’s ethanol oil recovery sys-
  tem, which Agri-Energy refused. J.A. 146–47. Agri-
  Energy’s maintenance manager testified that he felt that
  Mr. Winsness was offering “a royalty-free license in ex-
  change for admitting the patent was valid.” J.A. 146.
  Mr. Winsness testified that he had offered a royalty-free
  system to Agri-Energy in 2004 and an “early adopter ad-
  vantage” at an unspecified point in time. J.A. 269. Subse-
  quently, in July 2010, Cantor Colburn attorney Michael
  Rye provided Agri-Energy with a letter, asking Agri-En-
  ergy to “confirm” certain facts, including that VDT had not
  provided Agri-Energy with drawings or diagrams “for the

  not questioned [Mr.] Winsness’[s] veracity on other issues,
  the [District] Court could certainly conclude from this that
  [Mr.] Winsness has a propensity to evade the truth.”
  J.A. 266. For the purposes of our analysis, this point is an-
  cillary—albeit concerning regarding the candor of counsel
  and their clients—to the significant fact that Mr. Cantrell
  provided Agri-Energy with a version of the July 2003 Pro-
  posal by email on August 1, 2003, a fact that is now not
  disputed. J.A. 155; see J.A. 110274 (Second Cantrell Dec-
  laration).
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  16                 GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  proposed system in 2003” and that the system proposed to
  Agri-Energy was for testing purposes. J.A. 147; see
  J.A. 110322–23. Agri-Energy refused to verify the asser-
  tions, as it believed most of them to be “untrue.” J.A. 148.
  Soon after, Mr. Cantrell claimed to Cantor Colburn that he
  hand-delivered the July 2003 Proposal to Agri-Energy on
  August 18, 2003, despite the letter bearing a date weeks
  earlier. J.A. 148; see J.A. 70601.
      In November 2010, Cantor Colburn filed a declaration
  executed by Mr. Cantrell with the USPTO for the ’516 and
  ’517 patent applications and attached a copy of the
  July 2003 Proposal. The declaration explained that Mr.
  Cantrell had hand delivered the July 2003 Proposal to
  Agri-Energy on August 18, 2003. J.A. 148; see J.A. 110016–
  19 (First Cantrell Declaration). Cantor Colburn informed
  the USPTO that the July 2003 Proposal did not violate the
  on-sale bar, as it occurred less than a year before the appli-
  cation filing date. J.A. 148. Omitted from the disclosure
  was Mr. Barlage’s Test Report, the Ethanol Oil Recovery
  System Diagram, and Mr. Barlage’s June and July 2003
  testing. See generally J.A. 110016–19. The USPTO issued
  the ’516 and ’517 patents on August 30, 2011. See J.A. 910,
  921.
      In September 2011, Mr. Cantrell was deposed regard-
  ing the infringement lawsuit of the instant case. J.A. 148;
  see J.A. 20185–249. Mr. Cantrell was shown the July 2003
  Proposal emailed to Agri-Energy on August 1, 2003, and
  Mr. Cantrell testified that the email was not authentic.
  J.A. 278; see J.A. 20207–08. Mr. Cantrell later admitted
  that it was “possible” that he sent the August 1 email.
  J.A. 70601. Mr. Hagerty, when deposed in 2011, stated
  that “‘it sent a chill up his spine’” when he learned that the
  letter was sent on August 1, 2003. J.A. 278. The parties,
  however, had stipulated during the March to August 2010
  timeframe that Cantor Colburn was working under the im-
  pression that the July 2003 Proposal was sent on or near
  August 1, 2003. J.A. 278–79. Mr. Hagerty testified that he
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  GS CLEANTECH CORP. v. ADKINS ENERGY LLC                  17

  was unconcerned about the July 2003 Proposal because it
  did not “disclose anything or amount to an offer.” J.A. 279.
      In July 2012, Cantor Colburn withdrew the ’484 patent
  application, which also contained the First Cantrell Decla-
  ration, and filed a second declaration from Mr. Cantrell
  with the USPTO, which stated that Mr. Cantrell had for-
  gotten about sending the August 2003 Email with the
  July 2003 Proposal attached. J.A. 155, see J.A. 110274
  (Second Cantrell Declaration).        Notably, the Second
  Cantrell Declaration did not provide any retractions of the
  false information provided in the First Cantrell Declara-
  tion—that it misstated that the first delivery of the
  July 2003 Proposal was on August 18, 2003—and did not
  explain the significance of the email in the Second Cantrell
  Declaration, which indicated a pre-critical date offer for
  sale. See generally J.A. 110274. In October 2012, the ’484
  patent issued. J.A. 953.
                   III. Procedural History
     Starting in 2009 and continuing through 2014, Clean-
  Tech filed lawsuits against the Appellees 10 and Adkins

      10  The Appellees are: Big River Resources Galva,
  LLC; Big River Resources West Burlington, LLC; Lincoln-
  land Agri-Energy, LLC; Iroquois Bio-Energy Company,
  LLC; Cardinal Ethanol, LLC; Lincolnway Energy, LLC;
  ICM, Inc.; Bushmills Ethanol, Inc.; Al-Corn Clean Fuel,
  LLC; Chippewa Valley Ethanol Company, LLP; Heartland
  Corn Products; GEA Mechanical Equipment US, Inc., as
  Successor-in-Interest to GEA Westfalia Separator, Inc.;
  Ace Ethanol, LLC; Blue Flint Ethanol, LLC; United Wis-
  consin Grain Producers, LLC; Flottweg Separation Tech-
  nologies, Inc.; Aemetis, Inc.; Aemetis Advanced Fuels
  Keyes, Inc.; Little Sioux Corn Processors, LLLP; Guardian
  Energy, LLC; Western New York Energy, LLC; Southwest
  Iowa Renewable Energy, LLC; Pacific Ethanol Magic
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  18                 GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  Energy, LLC (“Adkins”) for infringement of the Patents-in-
  Suit and CleanTech’s U.S. Patent No. 8,168,037 (“the ’037
  patent”) in a number of actions that were subsequently
  combined into a multidistrict litigation case. In 2013,
  CleanTech moved for summary judgment. J.A. 1, 4–5. The
  Appellees and Adkins moved for, inter alia, summary judg-
  ment on invalidity. J.A. 3–5. The District Court found
  there was no infringement. J.A. 83, 86–87, 88, 90–91, 96.
  The District Court determined that specified claims in the
  lawsuit were invalid because of the on-sale bar, J.A. 174;
  anticipation, J.A. 181; obviousness, J.A. 192, 217; incorrect
  inventorship, J.A. 202; inadequate written description,
  J.A. 195; lack of enablement, J.A. 197, 219; and indefinite-
  ness, J.A. 205. 11
      Relevant here, the District Court determined that “un-
  disputed contemporaneous evidence supports only one con-
  clusion, the on-sale bar applies and invalidates the
  [Patents-in-Suit] because,” first, “the July [2003] Proposal
  was the culmination of a commercial offer for sale and,”
  second, “the method described in the [Patents-in-Suit] had
  either or both been reduced to practice or/and there was
  sufficient description of the patented method” by the criti-
  cal date to allow for the implementation of the patent.
  J.A. 167. 12 The District Court explained that the July 2003

  Valley LLC; Pacific Ethanol Stockton; Homeland Energy
  Solutions, LLC; Pacific Ethanol, Inc.; and David J. Vander
  Griend.
      11   Notably, the August 2003 Email and the accompa-
  nying July 2003 Proposal were not produced during discov-
  ery in the infringement litigation before the District Court.
  J.A. 134.
      12   The District Court initially determined that the on-
  sale bar did not apply to the ’484 patent, J.A. 174, but later
  clarified its ruling, explaining that independent claim 30 of
  the ’484 patent was invalid under the on-sale bar because
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  Proposal contained the “major elements of a contract for
  the sale of a system that could perform the patented
  method . . . : [namely] all items necessary to recover oil
  and the price.” J.A. 167. The District Court stated that the
  “dealing between the parties” leading up to the July 2003
  Proposal evidences both parties’ understanding that it was
  an offer for sale. J.A. 168. The District Court relied upon
  the communications between VDT and Agri-Energy, as
  VDT had advised Agri-Energy about the system, how it
  would work, what it was comprised of, where it should be
  placed, what it would accomplish, and the cost of operation.
  J.A. 168–69. The District Court concluded that, under the
  Uniform Commercial Code (“UCC”), the signed proposal
  would have constituted a commercial contract. J.A. 169.
  Further, the District Court explained that other evidence
  regarding VDT and Agri-Energy’s contact surrounding the
  July 2003 Proposal corroborated its conclusion. J.A. 169–
  70 (referencing the creation of the Ethanol Oil Recovery
  System Diagram and Mr. Winsness’s announcement to
  shareholders that VDT had made an offer to sell and that
  the sale would lead to other sales). The District Court ex-
  plained that a reasonable jury would not have concluded
  that the July 2003 Proposal was an offer to test its claimed
  invention as the Inventors knew the method could be suc-
  cessfully reduced to practice, J.A. 170–71 (listing evidence),
  and had been reduced to practice, J.A. 172 (citing Mr. Bar-
  lage’s two instances of practicing the method in 2003); see
  J.A. 172–73 (referencing other communications between
  the Inventors, Agri-Energy, and others implicating a re-
  duction to practice). Accordingly, the District Court inval-
  idated all of the claims of the ’859, ’516, and ’517 patents,

  it required the same steps as the claims of the ’859, ’516,
  and ’517 patents that were also invalid, J.A. 234–35.
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  20                  GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  and independent claim 30 of the ’484 patent pursuant to
  the on-sale bar. 13
      Following its summary judgment determinations, the
  District Court held an inequitable conduct bench trial.

       13  In addition to the Patents-in-Suit, the District
  Court addressed the ’037 patent, which was not included in
  the subsequent inequitable conduct bench trial. J.A. 237–
  38. The District Court determined that the ’037 patent was
  obvious over Prevost and the Patents-in-Suit. J.A. 215–16;
  see J.A. 214 (explaining that it was undisputed that the Pa-
  tents-in-Suit served as prior art to the ’037 patent). Spe-
  cifically, the District Court explained that Prevost and the
  Patents-in-Suit teach the oil recovery method for concen-
  trated thin stillage, which is used with evaporators, as is
  disclosed by the ’037 patent. J.A. 215–16. Compare ’858
  patent col. 5 ll. 28–30, with ’037 patent col. 10 ll. 56–67.
  The District Court stated that a person having ordinary
  skill in the art (“PHOSITA”) would have been “familiar
  with the prior art ethanol plant processes,” like Prevost,
  that “includ[e] evaporation of thin stillage to reduce the
  moisture content before mixing it with wet distiller
  grains[.]” J.A. 215. The District Court explained that the
  Patents-in-Suit disclose dryer efficiencies that can be
  achieved from the removal of oil from syrup prior to any
  mixing with wet distiller grains. J.A. 215–16. Compare
  ’858 patent col. 4 ll. 54–56, col. 5 ll. 28–30, with ’037 patent
  col. 10 ll. 61–67. Because Prevost and the Patents-in-Suit
  disclose the drying of syrup after the oil extraction process
  but before it is added back to the dried distiller wet grains,
  we conclude that the District Court properly determined
  that a PHOSITA would have been motivated to lower the
  moisture content of the syrup, as disclosed in the ’037 pa-
  tent. See Regents of Univ. of Cal. v. Broad Inst., Inc., 903
F.3d 1286, 1291 (Fed. Cir. 2018); see also 35 U.S.C.
  § 103(a).
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  GS CLEANTECH CORP. v. ADKINS ENERGY LLC                     21

  J.A. 237. Following the bench trial, in which the Inventors
  and attorneys from Cantor Colburn testified, the District
  Court concluded that additional evidence at trial supported
  the District Court’s previous determination that the Pa-
  tents-in-Suit were ready for patenting when the Inventors
  provided the July 2003 Proposal to Agri-Energy. J.A. 294.
  The District Court concluded that CleanTech committed
  inequitable conduct through a “complete lack of regard for
  their duty to the [USPTO].” J.A. 261. Moreover, the Dis-
  trict Court determined that “the [I]nventors made a mis-
  take” by “offer[ing] their invention for sale to Agri-Energy”
  in “July/August 2003,” and “[l]ater, they took affirmative
  steps to hide that fact from their lawyers, then, later [from]
  the [US]PTO when they learned that it would prevent
  them from profiting from the [Patents-in-Suit].” J.A. 299.
  The District Court stated that the Inventors “purposefully
  withheld the information about their dealings with Agri-
  Energy[,]” J.A. 263, and that they “acted to deceive the
  [US]PTO about the facts of the discovery process of the in-
  vention[,]” J.A. 261. In discussing the Inventors’ “inten[t]
  to deceive the [US]PTO,” the District Court stated that the
  conclusion was evidenced by the fact that the Inventors “al-
  lowed [Mr.] Hagerty to file the feasibility testing letter dur-
  ing prosecution of the [’]858 patent, but [did] not tell the
  whole story about their 2003 successes and the [July 2003
  Proposal].” J.A. 292. Moreover, “[w]ith respect to the
  [’]516, the [’]517, and the [’]484 patents,” the District Court
  determined that “the [I]nventors allowed [Mr.] Hagerty to
  file a false affidavit notwithstanding their knowledge that
  [Mr.] Barlage had practiced the method in June 2003 and
  they had made an offer to sell the method to Agri-Energy
  in July or early August of 2003.” J.A. 292–93.
      Additionally, the District Court concluded that Cantor
  Colburn either “purpose[fully] eva[ded]” disclosing or failed
  to seek out relevant information and so participated in the
  inequitable conduct, J.A. 264, “cho[o]s[ing] advocacy over
  candor[,]” J.A. 308. The District Court explained that Mr.
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  22                  GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  Hagerty “never asked the [I]nventors key questions about
  their invention or the meaning of contemporaneous docu-
  ments and, after the litigation started, [Mr. Hagerty] relied
  on the litigation team to do all the investigation.” J.A. 296.
  The District Court stated that Cantor Colburn’s focus on
  “pre-critical date documents” “was purposefully and, in
  [the District] Court’s view improperly narrow.” J.A. 300
  (internal quotation marks omitted). The District Court
  also found that “[i]n the face of [Mr.] Cantrell’s poor health,
  [Mr.] Winsness’[s] and Cantor Colburn’s reliance on [Mr.]
  Cantrell’s recollection of the events surrounding the
  [July 2003 Proposal] . . . , as well as their lackluster inves-
  tigation of events is solid evidence of purposeful behavior.”
  J.A. 307. The District Court determined that Cantor Col-
  burn “ignored the red flags [waving] before them[,]” such
  as the fact that Mr. Winsness “threatened Agri-Energy
  with legal action if it did not corroborate his and
  [Mr.] Cantrell’s story[,]” which Cantor Colburn supported
  by sending Agri-Energy a “thinly-veiled threat[.]” J.A. 307,
  308. 14 The District Court concluded that “[t]he only rea-
  sonable inference is that [Cantor Colburn] believed the
  [I]nventors had made an offer and, with the feasibility test-
  ing letter already before the [US]PTO in both

       14 At the bench trial, Mr. Hagerty testified that he
  had learned about the Inventors’ interactions with Agri-
  Energy around September 2008, including, significantly,
  the occurrence of the July 2003 testing. J.A. 263. When
  asked why he failed to provide the potential CleanTech in-
  vestor with that information, Mr. Hagerty “seemed per-
  plexed that [the] request should have covered the 2003
  testing because [Mr.] Hagerty had determined it was irrel-
  evant to patentability.” J.A. 263. We conclude, as the Dis-
  trict Court found, “[t]his conclusion is problematic in light
  of the fact that the written information [Mr.] Hagerty re-
  ceived from [Mr.] Winsness about the 2003 bench test
  stated that it worked[.]” J.A. 263.
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  GS CLEANTECH CORP. v. ADKINS ENERGY LLC                   23

  prosecutions, . . . which implied a later reduction to prac-
  tice date, they chose advocacy over candor.” J.A. 308. The
  District Court held the Patents-in-Suit unenforceable due
  to inequitable conduct. J.A. 313.
                          DISCUSSION
          I. Standard of Review and Legal Standard
       “Inequitable conduct is an equitable issue committed to
  the discretion of the trial court and is, therefore, reviewed
  by this court under an abuse of discretion standard.” En-
  ergy Heating, LLC v. Heat On-The-Fly, LLC, 889
F.3d 1291, 1299 (Fed. Cir. 2018) (citations omitted). We
  leave undisturbed the trial court’s inequitable conduct de-
  cision unless the appellant establishes “that the ruling is
  based upon clearly erroneous findings of fact or a misappli-
  cation or misinterpretation of applicable law or that the
  ruling evidences a clear error of judgment on the part of the
  [trial] court.” Kingsdown Med. Consultants, Ltd. v. Hollis-
  ter Inc., 863 F.2d 867, 876 (Fed. Cir. 1988) (citation omit-
  ted) (en banc in relevant part).
       To prevail on a claim of inequitable conduct in a patent
  case, the accused infringer must prove by clear and con-
  vincing evidence that the patentee: (1) “knew of the refer-
  ence” or prior commercial sale; (2) “knew that it was
  material”; and (3) “made a deliberate decision to withhold
  it.” See Therasense, Inc. v. Becton, Dickinson & Co., 649
F.3d 1276, 1290 (Fed. Cir. 2011) (en banc). “Proving that
  the [patentee] knew of a reference, should have known of
  its materiality, and decided not to submit it to the [US]PTO
  does not prove specific intent to deceive.” Id. Instead, “the
  specific intent to deceive must be the single most reasona-
  ble inference able to be drawn from the evidence.” Id. (in-
  ternal quotation marks and citation omitted).
      The inequitable conduct claim here relates to whether
  the patentee failed to disclose information that would have
  implicated the on-sale bar under 35 U.S.C. § 102(b). A
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  24                  GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  patent is invalid under the on-sale bar if, before the critical
  date, the invention was: (1) the subject of a commercial
  sale or offer for sale; and (2) “ready for patenting.” Pfaff,
525 U.S. at 67. First, whether the claimed invention was
  the subject of an offer for sale is an inquiry based on “con-
  tract law principles.” Linear Tech. Corp. v. Micrel, Inc., 275
F.3d 1040, 1048 (Fed. Cir. 2001). “It also involves an as-
  sessment of whether the circumstances surrounding the
  transaction show that the transaction was not primarily for
  purposes of experimentation.” Allen Eng’g Corp. v. Bartell
  Indus., Inc., 299 F.3d 1336, 1352–53 (Fed. Cir. 2002). “A
  use may be experimental only if it is designed to (1) test
  claimed features of the invention or (2) . . . determine
  whether an invention will work for its intended purpose[.]”
  Clock Spring, L.P. v. Wrapmaster, Inc., 560 F.3d 1317, 1327
  (Fed. Cir. 2009) (involving a question of public use and not
  the on-sale bar but stating that “[t]hough a prior commer-
  cial sale and not a prior public use was at issue in Allen
  Engineering, the factors explicated are equally relevant to
  an analysis of experimental use”). To determine if a trans-
  action was conducted primarily to experiment, a district
  court may look to the Allen factors to assess the transac-
  tion’s experimental nature. See Allen Eng’g, 299 F.3d
  at 1352–53. These factors include: “(1) the necessity for
  public testing, . . . (3) the nature of the invention,
  [and] . . . (10) whether the invention reasonably requires
  evaluation under actual conditions of use[.]” Id. (citation
  omitted). If a prior commercial sale was primarily for pur-
  poses of experimentation, the sale will not serve as a bar.
  See Clock Spring, 560 F.3d at 1327. “In making this pa-
  tentability determination, the [trial] court should apply the
  preponderance of the evidence standard[.]” Therasense,
649 F.3d at 1291–92.
      Second, “[a]n invention is ‘ready for patenting’ when
  prior to the critical date: (1) the invention is reduced to
  practice; or (2) the invention is depicted in drawings or de-
  scribed in writings of sufficient nature to enable a
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  GS CLEANTECH CORP. v. ADKINS ENERGY LLC                   25

  [PHOSITA] to practice the invention.” Hamilton Beach
  Brands, Inc. v. Sunbeam Prods., 726 F.3d 1370, 1375 (Fed.
  Cir. 2013) (citation omitted) (emphases added).
  II. The District Court Did Not Abuse Its Discretion in De-
    termining that the Patents-in-Suit Are Unenforceable
                 Due to Inequitable Conduct 15
     After a bench trial, the District Court concluded that
  CleanTech and its attorneys at Cantor Colburn engaged in

      15   Despite CleanTech’s arguments to the contrary, see
  Appellant’s Reply Br. 4, we will address the issue of ineq-
  uitable conduct without first conducting a de novo review
  of the District Court’s summary judgment on-sale bar de-
  termination. A finding of a reference’s or prior sale’s ma-
  teriality is required for an inequitable conduct
  determination, see Therasense, 649 F.3d at 1290, which is
  reviewed for abuse of discretion, see Energy Heating, 889
F.3d at 1299. CleanTech contends that materiality may
  not be reviewed in the context of the inequitable conduct
  claim, as materiality was not properly raised before and
  addressed by the District Court during the inequitable con-
  duct bench trial. Appellant’s Reply Br. 4–5. This argument
  is jejune. The District Court held an eight-day bench trial
  in which materiality was squarely before it. In addition to
  incorporating the evidence and findings of materiality that
  had been presented at the summary judgment stage,
  J.A. 237, the District Court admitted other relevant evi-
  dence during the trial, including documents relating to the
  June and July 2003 testing, J.A. 40144–45, 40153–54, and
  previously unheard testimony from the Inventors and at-
  torneys with Cantor Colburn, J.A. 294, all relating to the
  materiality of the July 2003 Proposal. Moreover, following
  the bench trial, the District Court determined that “its con-
  clusion [from the Summary Judgment Order] that [the
  July 2003 Proposal] evidence both elements of the on-sale
  bar” was “confirm[ed]” and, after incorporating “by
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  26                  GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  inequitable conduct in obtaining the Patents-in-Suit, ren-
  dering the patents unenforceable. J.A. 313. On appeal,
  CleanTech argues that the District Court made clearly er-
  roneous findings of fact and misapplied the law with re-
  spect to its on-sale bar determination, as well as its
  conclusions regarding the parties’ knowledge of materiality
  and their intent to deceive. Appellant’s Br. 104, 109–10.
  We disagree with CleanTech.
                         A. On-Sale Bar
      The District Court “conclude[d] that the undisputed
  contemporaneous evidence supports only one conclusion,
  [that] the on-sale bar applies and invalidates the [Patents-
  in-Suit] because” the claimed invention was the subject of
  an offer for commercial sale and it was ready for patenting.
  J.A. 167. We address each determination in turn.
   1. The District Court Did Not Abuse Its Discretion in De-
    termining the Claimed Invention Was the Subject of a
                Pre-Critical Date Offer for Sale
     The District Court concluded that the July 2003 Pro-
  posal constituted a pre-critical-date offer for sale. J.A. 299.

  reference the findings of fact and conclusions of law in the
  Summary Judgment Order,” the District Court determined
  that “[f]urther evidence at trial only buttresse[d] the [Dis-
  trict] Court’s earlier conclusion, particularly with respect
  to the ready for patenting element of the on-sale bar.” J.A.
  294. Additionally, despite CleanTech’s suggestions to the
  contrary, see Appellant’s Br. 105, inequitable conduct’s ma-
  teriality requirement does not provide the patentee with
  the right to a jury and instead must be resolved by the trial
  court, see Am. Calcar, Inc. v. Am. Honda Motor Co., Inc.,
  651 F.3d 1318, 1333 (Fed. Cir. 2011) (“Inequitable conduct
  is equitable in nature, with no right to a jury, and the trial
  court has the obligation to resolve the underlying facts of
  materiality and intent.”).
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  CleanTech contends that it was not an offer as it “did not
  in fact perform the method for Agri-Energy, before the crit-
  ical date, for a promise of future compensation.” Appel-
  lant’s Br. 37 (internal quotation marks and emphasis
  omitted) (citing Plumtree Software, Inc. v. Datamize, LLC,
  473 F.3d 1152, 1162–63 (Fed. Cir. 2006)). We disagree with
  CleanTech.
       The District Court did not abuse its discretion in deter-
  mining that the claimed invention was the subject of an of-
  fer for sale in the summer of 2003. First, relying on the
  UCC, the District Court concluded that the July 2003 Pro-
  posal was a “sale on approval” that was made before the
  critical date. J.A. 169 (citing U.C.C. § 2-326); see U.C.C.
  § 2-326(1)(a) (“[I]f delivered goods may be returned by the
  buyer even though they conform to the contract, the trans-
  action is . . . a ‘sale on approval’ if the goods are delivered
  primarily for use[.]”); see also Linear, 275 F.3d at 1052 (ex-
  plaining “that the [UCC] should inform the [district court’s]
  analysis of the contractual issues[,]” such as the on-sale
  bar). The July 2003 Proposal provides an offer of “all items
  necessary to recover oil and the price,” J.A. 167, and the
  Inventors understood the offer to Agri-Energy was a “first
  sale” that would lead to additional sales, J.A. 170–72. Ac-
  cordingly, the District Court properly concluded that the
  July 2003 Proposal was an “offer for sale.” Pfaff, 525 U.S.
  at 67.
        CleanTech’s primary counterargument is unavailing.
  CleanTech contends that the District Court misconstrued
  the law by failing to apply Plumtree’s requirement that the
  “challenger must prove that the patentee either: (i) ‘made
  a commercial offer to perform the patented method[]’[;] or
  (ii) ‘in fact performed the patented method for a promise of
  future compensation.’” Appellant’s Br. 36. CleanTech,
  however, did not make this argument before the District
  Court and cited to Plumtree only once in its summary judg-
  ment opposition and only for the proposition that the
  July 2003 Proposal was not invalidating because it “did not
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  28                  GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  unambiguously require use of [CleanTech’s] patented
  methods[.]” J.A. 26364 (citing Plumtree, 473 F.3d at 1163).
  Because we apply the law of the regional circuit as to pro-
  cedural matters, see Info-Hold, Inc. v. Muzak LLC, 783
F.3d 1365, 1371 (Fed. Cir. 2015), here the Seventh Circuit,
  we will not decide an issue for the first time on appeal, see
  Scheurer v. Fromm Family Foods LLC, 863 F.3d 748, 755
  (7th Cir. 2017) (“The well-established rule in th[e Seventh]
  Circuit is that a plaintiff waives the right to argue an issue
  on appeal if she fails to raise the issue before a lower court.”
  (internal quotation marks and citation omitted)).
   2. The District Court Did Not Abuse Its Discretion in De-
   termining the Claimed Invention Was Ready for Patent-
                  ing Before the Critical Date
       The District Court determined that the claimed inven-
  tion was ready for patenting prior to the critical date.
  J.A. 167. CleanTech contends that the District Court failed
  to find that the claimed invention was reduced to practice
  “on a claim-by-claim basis” for each of the Patents-in-Suit.
  Appellant’s Br. 46. We disagree with CleanTech.
      The District Court did not abuse its discretion in deter-
  mining the claimed invention was ready for patenting in
  June or July 2003. First, with respect to the reduction to
  practice, the District Court relied upon the two tests con-
  ducted by Mr. Barlage in the summer of 2003 to support its
  determination. J.A. 126–27; see Hamilton Beach Brands,
726 F.3d at 1375 (“An invention is ‘ready for patenting’
  when prior to the critical date: . . . the invention is reduced
  to practice[.]” (emphasis added) (citation omitted)). The
  District Court explained that, in June 2003, Mr. Barlage
  tested an ethanol syrup with a pH, moisture content, and
  temperature within the claimed ranges recited in the Pa-
  tents-in-Suit, compare J.A. 125–26 (describing Mr. Bar-
  lage’s testing, which heated thin stillage to a temperature
  of 176 ºF, with a pH of “approximately 4, and moisture con-
  tent between 70% and 80%”), with J.A. 920 (’516 patent)
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  GS CLEANTECH CORP. v. ADKINS ENERGY LLC                  29

  (Dependent Claim 6) (reciting “[a] method of recovering oil
  from thin stillage” with a temperature between 150 ºF and
  212 ºF, a pH between 3 and 6, and a moisture content of
  greater than 30% and less than 90% by weight), and sepa-
  rated oil from the syrup with a centrifuge, reporting that
  “the oil can be taken out easily,” J.A. 125–26, 171. Indeed,
  the Inventors themselves made statements contemporane-
  ous to the June and July 2003 testing that the claimed in-
  vention was reduced to practice. J.A. 127 (Mr. Cantrell
  stating to Agri-Energy following the July 2003 Test that
  “‘[t]he technology is available to remove the oil, and the
  quick payback from the new revenue stream, make this a
  very viable program’”), 111065 (Mr. Dorisio’s Draft Clear-
  ance Opinion to the Inventors) (“Past correspondence indi-
  cates your actual reduction to practice of the removing oil
  from syrup aspect of the proposed invention during experi-
  ments conducted in early to mid-June 2003.” (emphases
  added)). Moreover, immediately following the July 2003
  Test, Mr. Winsness then directed a VDT employee to pre-
  pare the Ethanol Oil Recovery System Diagram, J.A. 130–
  32; see J.A. 110044 (Ethanol Oil Recovery System Dia-
  gram), which the employee understood “was intended to be-
  come a sales drawing[,]” J.A. 132 (internal quotation marks
  omitted); see J.A. 246 (the VDT employee “understood that
  the drawings would be used for sales purposes by [Mr.]
  Cantrell and [Mr.] Winsness”). The District Court, after
  reviewing the evidence, did not abuse its discretion in de-
  termining that “the method of the patented inven-
  tion . . . had been performed” during June and July 2003.
  J.A. 171.
      CleanTech’s counterarguments are meritless and mis-
  leading. CleanTech disputes the District Court’s determi-
  nation that the June and July 2003 testing was not
  experimental, arguing that there were “genuine factual
  disputes on [its] ‘commercial’ v[ersus] ‘experimental’” na-
  ture. Appellant’s Br. 39 (capitalization modified). Specifi-
  cally, CleanTech argues that “nearly all” of the Allen
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  30                  GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  factors support the experimental nature of the July 2003
  Proposal. Id. at 40. As an initial matter, CleanTech mis-
  represents the Allen factors and supports its arguments
  with testimony that was discredited by the District Court.
  Compare id. (“Allen factors [one] and [ten] ask whether the
  inventors ‘needed’ to experiment with the invention ‘under
  actual conditions of use.’” (internal brackets and emphasis
  omitted)), with Allen Eng’g, 299 F.3d at 1353 (explaining
  that factor one assesses whether there is “the necessity for
  public testing” and factor ten addresses “whether the in-
  vention reasonably requires evaluation under actual condi-
  tions of use”).       CleanTech argues its testing was
  experimental because its claimed invention “clearly”
  “‘needed’ to experiment with the invention ‘under actual
  conditions of use.’” Appellant’s Br. 40 (quoting Allen Eng’g,
299 F.3d at 1353) (internal brackets omitted). The District
  Court did not abuse its discretion in discounting this argu-
  ment, as it explained that a “reduction to practice does not
  require a showing that the method would work acceptably
  in a plant environment, unless the claims require it, and
  the claims here do not.” J.A. 172 (internal quotation marks
  and citation omitted); see In re Cygnus Telecomms. Tech.,
  LLC, 536 F.3d 1343, 1355 (Fed. Cir. 2008) (explaining that
  a system that would not have worked on a “commercial
  scale[,]” but that “embodied the claims” of the “patents at
  issue[,]” satisfied the “‘ready for patenting’ prong” of the on-
  sale bar). The District Court considered the Allen factors
  and concluded that the offer to Agri-Energy was an offer
  for sale and not for purposes of experimentation. J.A. 167;
  see Allen Eng’g, 299 F.3d at 1352–53. For these reasons,
  we conclude that the District Court did not clearly err in
  its determination.
      Second, the District Court found the claimed invention
  was ready for patenting because it had been depicted and
  described in such a way that a PHOSITA would be able to
  practice it. J.A. 172–73; see Hamilton Beach Brands, 726
F.3d at 1375 (“An invention is ‘ready for patenting’ when
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  GS CLEANTECH CORP. v. ADKINS ENERGY LLC                    31

  prior to the critical date . . . the invention is depicted in
  drawings or described in writings of sufficient nature to en-
  able a [PHOSITA] to practice the invention.” (emphasis
  added) (citation omitted)). Despite CleanTech’s argument
  that its expert opined the Inventors had not prepared
  drawings or other descriptions of the invention that were
  sufficiently specific to enable a PHOSITA to practice it, see
  Appellant’s Reply Br. 18 (emphasis omitted), Appellant’s
  Br. 47, the District Court determined that, while there was
  no “single reference that specifically delineate[d]” the
  method “disclosed by the [Patents-in-Suit], the Ethanol
  [Oil Recovery] System Diagram” in combination “with
  [Mr.] Barlage’s lab tests and results” and “communications
  from [Mr.] Cantrell to Agri-Energy . . . would allow a
  [PHOSITA] to practice the invention of the [Patents-in-
  Suit,]” J.A. 173. The District Court explained that “[t]here
  is no mystery or dispute that the pH, moisture content[,]
  and temperature ranges in the claims of the [Patents-in-
  Suit] are those that occur at the standard operating condi-
  tions of a dry mill ethanol plant.” J.A. 173. CleanTech has
  not shown clear error in these factual findings and we re-
  ject the invitation to reweigh the evidence. Accordingly,
  the District Court did not abuse its discretion in its on-sale
  bar determination.
     B. The District Court Did Not Abuse Its Discretion in
   Concluding that CleanTech and Its Lawyers Made a De-
   liberate Decision to Withhold Material Information with
           the Specific Intent to Deceive the USPTO
      The District Court concluded that CleanTech knew of
  the claimed invention’s offer for sale and reduction to prac-
  tice in the summer of 2003, as well as that information’s
  materiality. J.A. 303, 308. The District Court “conclude[d]
  that the [I]nventors and the[ir] attorneys intentionally
  withheld material information from the [US]PTO during
  prosecution” of the Patents-in-Suit, thereby rendering the
  Patents-in-Suit unenforceable due to inequitable conduct.
  J.A. 312; see Therasense, 649 F.3d at 1290 (explaining that
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  32                 GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  inequitable conduct requires a showing of clear and con-
  vincing evidence that the patentee “knew of the reference,
  knew that it was material, and made a deliberate decision
  to withhold it”). CleanTech contends that that District
  Court erred in its materiality and intent to deceive find-
  ings. Appellant’s Br. 104–05. We disagree with Clean-
  Tech.
       The District Court did not abuse its discretion in ren-
  dering unenforceable the Patents-in-Suit for inequitable
  conduct. For the reasons discussed above, see supra Sec-
  tion II.A, we conclude that the District Court did not abuse
  its discretion in concluding that CleanTech and its attor-
  neys were aware that the claimed invention was ready for
  patenting, as evidenced by documents belatedly or not
  turned over to the USPTO, and that they knew of those
  documents’ materiality. In addition to knowledge and ma-
  teriality, inequitable conduct requires a clear and convinc-
  ing showing that CleanTech “made a deliberate decision to
  withhold” the material information. See Therasense, 649
F.3d at 1290. Moreover, “the specific intent to deceive must
  be ‘the single most reasonable inference drawn from the ev-
  idence.’” Id. Here, the District Court did not abuse its dis-
  cretion in determining for numerous reasons that
  CleanTech deliberately withheld material information.
      First, the District Court concluded that CleanTech
  knew the July 2003 Proposal to Agri-Energy threatened its
  chances of patenting its ethanol oil recovery method.
  J.A. 299 (explaining “that the [I]nventors made a mistake
  in July/August 2003 and offered their invention for sale to
  Agri-Energy” and “[l]ater . . . took affirmative steps to hide
  that fact from their lawyers, then, later the [US]PTO when
  they learned that it would prevent them from profiting
  from the patents”). This determination is supported by the
  record. In February 2004, the Inventors sought infor-
  mation from the USPTO website about provisional patent
  applications and the on-sale bar. J.A. 252. Days later, Mr.
  Dorisio informed the Inventors about the on-sale bar.
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  J.A. 252. The District Court did not clearly err in finding
  that CleanTech was aware of the on-sale bar and its re-
  quirements. See Energy Heating, 889 F.3d at 1302–03
  (concluding that the district court did not abuse its discre-
  tion in finding an inventor’s knowledge that sales of the
  claimed invention prior to the critical date were material,
  and the inventor’s failure to disclose the sales was intended
  to deceive the USPTO).
       Second, the District Court found that the Inventors and
  the attorneys at Cantor Colburn withheld evidence of suc-
  cessful testing in 2003 and made false representations by
  implying that the invention was not reduced to practice un-
  til 2004. J.A. 302 (“[N]ot providing information regarding
  the [I]nventors’ dealings with Agri-Energy or [Mr.] Bar-
  lage[’s] bench-top test raises an inference that the patent-
  ees intended to deceive the [US]PTO—it was pre-critical
  date information that had a direct bearing on the ability of
  the [I]nventors to prove that their claims were patenta-
  ble.”). This finding is supported by the record. Cantor Col-
  burn began representing CleanTech in March 2008 and, by
  at least September 2008, were aware of Mr. Barlage’s test-
  ing in June and July 2003. J.A. 111075. Mr. Winsness in-
  formed Cantor Colburn that the “testing we did in
  June 2003” showed that “a sequence of evaporation fol-
  lowed by centrifugation allows for oil recovery[.]”
  J.A. 111075. Moreover, the Inventors informed Cantor
  Colburn that, based on the summer 2003 testing, the In-
  ventors “believe[d] [that] the process would work on a com-
  mercial scale.”     J.A. 263 (internal quotation marks
  omitted). Cantor Colburn was also in possession of the
  Ethanol Oil Recovery System Diagram and the test reports
  themselves. J.A. 301. Despite possessing this information,
  Cantor Colburn did not provide it to the USPTO during the
  prosecution of the Patents-in-Suit and referenced it only to
  assert that the claimed invention predated Prevost.
  J.A. 301–02, 304–06, 309. Moreover, in June 2009, Cantor
  Colburn filed a letter with the USPTO stating that
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  34                 GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  feasibility testing occurred in May 2004, with no mention
  of the documents dated a year earlier. J.A. 303. This letter
  was filed in the prosecutions of each of the Patents-in-Suit.
  J.A. 304–05. The District Court did not clearly err in its
  finding that CleanTech and Cantor Colburn withheld ma-
  terial evidence from the USPTO. See Molins PLC v. Tex-
  tron, Inc., 48 F.3d 1172, 1178 (Fed. Cir. 1995) (“[Patentees]
  who are not ‘up front’ with the [US]PTO run the risk that,
  years later, a fact-finder might conclude they intended to
  deceive. This is what appears to have happened here and
  we must affirm the trial court.”); see also id. (“Applicants
  for patents are required to prosecute patent applications in
  the [US]PTO with candor, good faith, and honesty. . . . This
  duty extends also to the applicant’s representatives.” (in-
  ternal footnote and citations omitted)).
      Third, the District Court determined that CleanTech
  and Cantor Colburn “threatened” Agri-Energy to coerce its
  support regarding the critical date for the Patents-in-Suit,
  after the July 2003 Proposal surfaced and during the pen-
  dency of the ’516 and ’517 patents. J.A. 308. Specifically,
  in June 2009, Mr. Winsness traveled to Agri-Energy and
  “offered Agri-Energy a royalty-free license in exchange for
  Agri-Energy’s willingness to admit that the pending pa-
  tents were valid.” J.A. 269. In July 2009, Cantor Colburn
  sent Agri-Energy an email offering “a release of liability for
  any prior use of an extraction system” and indemnification
  “against any liability” in return “for cooperating with
  [CleanTech] and for clarifying the use of the corn oil system
  in 2004.” J.A. 110322. Moreover, Cantor Colburn re-
  quested a statement “confirming and clarifying” certain
  facts relating to the offer. J.A. 110322–23. Agri-Energy’s
  manager testified that he “did not accept the offer from
  [Cantor Colburn and CleanTech] because the statements
  were not true.” J.A. 271. Notably, Cantor Colburn “failed
  to request that Agri-Energy provide any documents” re-
  garding its interactions with the Inventors. J.A. 271. The
  District Court did not abuse its discretion in concluding
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  that these attempts to threaten Agri-Energy spoke to
  CleanTech’s and Cantor Colburn’s intent to deceive the
  USPTO.
      Fourth, the District Court concluded that the Inventors
  and Cantor Colburn made a “patently false” statement in
  the First Cantrell Declaration, by claiming the July 2003
  Proposal was delivered to Agri-Energy after the critical
  date. J.A. 276; see J.A. 307 (“[T]he [I]nventors and attor-
  neys misrepresented to the [US]PTO that the [July 2003
  Proposal] was immaterial by filing the false [First]
  Cantrell . . . Declaration[.]”). The District Court’s determi-
  nation that the declaration was false is supported by the
  evidence. Specifically, it was not until August 2010 that
  Mr. Cantrell told Cantor Colburn that he recalled he had
  personally delivered the July 2003 Proposal to Agri-Energy
  on August 18, 2003. J.A. 272. The attorneys at Cantor
  Colburn testified that they themselves were skeptical of
  the veracity of the claim, as the date specified by Mr.
  Cantrell would alleviate all concerns about the on-sale bar.
  J.A. 272–73. Nonetheless, Cantor Colburn filed the First
  Cantrell Declaration in November 2010 for the ’516 and
  ’517 patent prosecutions, J.A. 276–77, and in the ’484 pa-
  tent prosecution in July 2011, J.A. 277. This was done not-
  withstanding the Inventors’ knowledge that Mr. Barlage
  had practiced the claimed method in June 2003 and they
  had offered to sell the claimed invention to Agri-Energy in
  July or early August of 2003. J.A. 292–93; see Rohm &
  Haas Co. v. Crystal Chem. Co., 722 F.2d 1556, 1571 (Fed.
  Cir. 1983) (“[T]here is no room to argue that submission of
  false affidavits is not material.”). Moreover, prior to Mr.
  Cantrell’s August 2010 statement, Cantor Colburn had
  prepared a detailed disclosure that included information
  about the June and July 2003 Tests and Report and the
  Ethanol Oil Recovery System Diagram, which the law firm
  had possessed since September 2008. J.A. 308; see
  J.A. 111075–104 (Email from Mr. Winsness to Mr. Hagerty
  Dated September 2008) (providing “some history of testing
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  36                 GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  we did in June 2003 to discover that a sequence of evapo-
  ration followed by centrifugation allows for oil recovery[,]”
  including the June 2003 Report). Following Mr. Cantrell’s
  statements, the disclosure was discarded and never filed in
  any patent prosecution. J.A. 308. Based on this, the Dis-
  trict Court concluded that “[t]he only reasonable inference
  is that [Cantor Colburn] believed the [I]nventors had made
  an offer and, with the feasibility testing letter already be-
  fore the [US]PTO in both prosecutions, . . . which implied a
  later reduction to practice date, they chose advocacy over
  candor.” J.A. 308 (emphases added). The District Court
  did not abuse its discretion in concluding that the “patently
  false” statement in the First Cantrell Declaration was ma-
  terial and supported its intent to deceive determination.
       Fifth, the District Court explained that the Inventors’
  and Cantor Colburn’s failure to correct the false declara-
  tion in the ’484 patent prosecution was “strong evidence of
  intentional deceit[.]” J.A. 309. Specifically, at Mr.
  Cantrell’s September 2011 deposition, where Mr. Cantrell
  and Cantor Colburn “kn[e]w for certain that [Mr.]
  Cantrell’s First Declaration [was] false,” no correction was
  made then or during the following eight months. J.A. 309
  (emphasis added); see J.A 280 (“Most disturbing is that,
  during this period, neither litigation counsel nor [Mr.]
  Hagerty did anything to alert the [US]PTO that [Mr.]
  Cantrell’s First Declaration was false[.]”). In July 2012,
  the Second Cantrell Declaration was filed with the USPTO,
  in which Mr. Cantrell attested that “[a]ttached is an e-mail
  sent from my e-mail account on August 1, 2003” and that
  “[t]he [July 2003 Proposal] attached to the August 1 email
  was unsigned.” J.A. 110274. As the District Court ex-
  plained, the Second Cantrell Declaration provided “the
  false impressions that [Mr.] Cantrell may not have sent the
  [August 2003 Email] and that the unsigned letter had less
  significance than the ‘signed’ one he allegedly hand deliv-
  ered later the same month,” it “repeats false information,”
  and “fails to distinctly point out and/or explain the false
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  GS CLEANTECH CORP. v. ADKINS ENERGY LLC                    37

  information previously provided to the examiner[.]”
  J.A. 283. Based on this evidence, we conclude that the Dis-
  trict Court did not abuse its discretion in concluding that,
  by clear and convincing evidence, the single most reasona-
  ble inference to be drawn from the record was that the In-
  ventors and Cantor Colburn intended to deceive the
  USPTO. See Energy Heating, 889 F.3d at 1302–03.
       CleanTech raises numerous counterarguments, all of
  which are unavailing. First, CleanTech argues that the
  District Court’s review of materiality “exceeded the scope
  of the bench trial, which was only on ‘inequitable conduct.’”
  Appellant’s Br. 105. Materiality is, however, an element of
  the inequitable conduct claim and was squarely before the
  District Court. See Therasense, 649 F.3d at 1290 (“In a case
  involving nondisclosure of information, clear and convinc-
  ing evidence must show that the applicant made a deliber-
  ate decision to withhold a known material reference.”
  (internal quotation marks and citation omitted) (emphasis
  altered)). In fact, CleanTech itself raised materiality in
  pre-trial briefing, contending that the Appellants “will also
  not be able to establish that any of the alleged errors and
  omissions, aside from the misstatements found in [Mr.]
  Cantrell’s first declaration, would have been ‘but-for’ mate-
  rial.” J.A. 63467. Accordingly, the District Court did not
  err in making a materiality determination.
      Second, CleanTech avers that the District Court’s ma-
  teriality finding violated its right to a jury trial. Appel-
  lant’s Br. 105. Given that inequitable conduct is based in
  equity, there is no right to a jury trial. See Am. Calcar, 651
F.3d at 1333 (“Inequitable conduct is equitable in nature,
  with no right to a jury, and the trial court has the obliga-
  tion to resolve the underlying facts of materiality and in-
  tent.”).
      Third, CleanTech contends that the District Court
  “barred CleanTech from re-litigating materiality” by ex-
  cluding some evidence involving the USPTO’s actions
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  38                 GS CLEANTECH CORP. v. ADKINS ENERGY LLC

  permitting “a continuation in the [Patents-in-Suit]” even
  after the USPTO was provided with evidence of the July
  2003 Proposal and related materials. Appellant’s Br. 105–
  06. The evidence was excluded under Federal Rule of Evi-
  dence 403, because the District Court determined that its
  probative value was outweighed by the likelihood that it
  would confuse and prolong the trial. J.A. 71952–53; see
  Fed. R. Evid. 403 (“The court may exclude relevant evi-
  dence if its probative value is substantially outweighed by
  a danger of one or more of the following: unfair prejudice,
  confusing the issues, . . . undue delay, [or] wasting
  time[.]”). To the extent that CleanTech is contesting the
  Rule 403 determination, it did not do so before the District
  Court and so waives the issue here. See Scheurer, 863 F.3d
  at 755. Accordingly, the District Court did not abuse its
  discretion in reaching its inequitable conduct determina-
  tion. 16
                         CONCLUSION
      We have considered the parties’ other arguments and
  each of the remaining issues raised on appeal and cross-
  appeal and find them to be without merit. Accordingly, the
  judgments below are
                         AFFIRMED

       16  As we affirm the District Court’s determination
  that the Patents-in-Suit are unenforceable due to the ineq-
  uitable conduct, we need not address CleanTech’s addi-
  tional arguments regarding the other grounds upon which
  the District Court ruled the Patents-in-Suit invalid. See
  Energy Heating, 889 F.3d at 1308 (concluding that, where
  a trial court’s judgment that a “patent is unenforceable for
  inequitable conduct” is affirmed, this court need “not reach
  the [trial] court’s summary judgment of obviousness, claim
  construction order, or summary judgment of no direct in-
  fringement”).
Case: 16-2231   Document: 164      Page: 39   Filed: 03/02/2020

  GS CLEANTECH CORP. v. ADKINS ENERGY LLC                39

                           COSTS
      Costs to the Appellees and Cross-Appellant.