Court Opinion

ID: 4361522
Source: CourtListenerOpinion
Date Created: 2019-01-24 16:00:58.343181+00
Date Added: 2024-06-11T14:48:18.877608
License: Public Domain

United States Court of Appeals
      for the Federal Circuit
                ______________________

                  MARK A. BARRY,
                   Plaintiff-Appellee

                           v.

                 MEDTRONIC, INC.,
                 Defendant-Appellant
                ______________________

                      2017-2463
                ______________________

   Appeal from the United States District Court for the
Eastern District of Texas in No. 1:14-cv-00104-RC, Chief
Judge Ron Clark.
                 ______________________

               Decided: January 24, 2019
                ______________________

    DAVID CLAY HOLLOWAY, Kilpatrick Townsend &
Stockton LLP, Atlanta, GA, argued for plaintiff-appellee.
Also represented by COURTNEY DABBIERE; ADAM HOWARD
CHARNES, Dallas, TX; ERWIN CENA, San Diego, CA; DARIO
ALEXANDER MACHLEIDT, Seattle, WA; SEAN PAUL
DEBRUINE, Law Office of Sean DeBruine, Menlo Park,
CA.

   SETH P. WAXMAN, Wilmer Cutler Pickering Hale and
Dorr LLP, Washington, DC, argued for defendant-
appellant. Also represented by BRITTANY BLUEITT AMADI;
MARK CHRISTOPHER FLEMING, Boston, MA; MARY-OLGA
2                                   BARRY v. MEDTRONIC, INC.

LOVETT, Greenberg Traurig LLP, Houston, TX; JULIE
PAMELA BOOKBINDER, SCOTT JOSEPH BORNSTEIN, ALLAN A.
KASSENOFF, RICHARD CHARLES PETTUS, New York, NY.
               ______________________

        Before PROST, Chief Judge, MOORE and TARANTO,
                      Circuit Judges.
    Opinion for the court filed by Circuit Judge TARANTO.
    Opinion dissenting in part filed by Chief Judge PROST.
TARANTO, Circuit Judge.
     Dr. Mark Barry brought this action against Medtron-
ic, Inc., alleging that Medtronic induced surgeons to
infringe U.S. Patent Nos. 7,670,358 and 8,361,121, which
Dr. Barry owns and which name him as the sole inventor.
The jury found infringement of method claims 4 and 5 of
the ’358 patent and system claims 2, 3, and 4 of the ’121
patent, rejected Medtronic’s several invalidity defenses,
and awarded damages. In post-trial rulings on the jury
issues, Barry v. Medtronic, Inc., 230 F. Supp. 3d 630 (E.D.
Tex. 2017) (Barry), the district court upheld the verdict as
relevant here—rejecting challenges as to induced in-
fringement and associated damages for domestic conduct,
id. at 640–47, 650–51, invalidity of the asserted ’358
patent claims under the public-use and on-sale bars, id. at
653–59, and invalidity of all asserted claims due to anoth-
er’s prior invention, id. at 659–63. The district court then
rejected Medtronic’s inequitable-conduct challenge, Barry
v. Medtronic, Inc., 245 F. Supp. 3d 793, 823 (E.D. Tex.
2017) (Inequitable Conduct Op.), and, in a ruling not
separately challenged on appeal, enhanced damages by
twenty percent while denying attorney’s fees to Dr. Barry,
Barry v. Medtronic, Inc., 250 F. Supp. 3d 107, 111, 119
(E.D. Tex. 2017) (Enhancement Op.). Medtronic appeals
on numerous grounds, principally concerning the public-
use and on-sale statutory bars, but also concerning prior
BARRY v. MEDTRONIC, INC.                                    3

invention, inequitable conduct, and induced infringement
and associated damages. We affirm.
                              I
                             A
     Both patents at issue are entitled “System and Meth-
od for Aligning Vertebrae in the Amelioration of Aberrant
Spinal Column Deviation Conditions.” The patents claim
methods and systems for correcting spinal column anoma-
lies, such as those due to scoliosis, by applying force to
multiple vertebrae at once. ’358 patent, col. 2, line 63,
through col. 3, line 6; ’121 patent, col. 3, line 53, through
col. 4, line 2. The ’358 issued in 2010 from an application
that Dr. Barry filed on December 30, 2004. The ’121
patent issued in 2013 from an application—a continuation
of an August 2005 application that was a continuation-in-
part of the December 30, 2004 application—that Dr.
Barry filed in 2010.
    The asserted claims of the ’358 patent are method
claims 4 and 5. They depend ultimately on independent
claim 1, which reads:
    1. A method for aligning vertebrae in the ame-
    lioration of aberrant spinal column deviation con-
    ditions comprising the steps of:
      selecting a first set of pedicle screws, said pedi-
      cle screws each having a threaded shank seg-
      ment and a head segment;
      selecting a first pedicle screw cluster derotation
      tool, said first pedicle screw cluster derotation
      tool having first handle means and a first group
      of pedicle screw engagement members which
      are mechanically linked with said first handle
      means, each pedicle screw engagement member
      being configured for engaging with, and trans-
      mitting manipulative forces applied to said first
4                                BARRY v. MEDTRONIC, INC.

    handle means to said head segment of each
    pedicle screw of said first set of pedicle screws,
    implanting each pedicle screw in a pedicle re-
    gion of each of a first group of multiple verte-
    brae of a spinal column which exhibits an
    aberrant spinal column deviation condition;
    engaging each pedicle screw engagement mem-
    ber respectively with said head segment of each
    pedicle screw of said first set of pedicle screws;
    and
    applying manipulative force to said first handle
    means in a manner for simultaneously engag-
    ing said first group of pedicle screw engage-
    ment members and first set of pedicle screws
    and thereby in a single motion simultaneously
    rotating said vertebrae of said first group of
    multiple vertebrae in which said pedicle screws
    are implanted to achieve an amelioration of an
    aberrant spinal column deviation condition;
    selecting a first length of a spinal rod member;
    wherein one or more of said pedicle screws of
    said first set of pedicle screws each includes:
      a spinal rod conduit formed substantially
      transverse of the length of said pedicle screw
      and sized and shaped for receiving passage
      of said spinal rod member therethrough; and
      spinal rod engagement means for securing
      said pedicle screw and said spinal rod mem-
      ber, when extending through said spinal rod
      conduit, in a substantially fixed relative po-
      sition and orientation;
    extending said first length of said spinal rod
    member through said spinal rod conduits of one
BARRY v. MEDTRONIC, INC.                                    5

      or more of said pedicle screws of said first set of
      pedicle screws; and
      after applying said manipulative force to said
      first handle means, actuating said spinal rod
      engagement means to secure said vertebrae in
      their respective and relative positions and ori-
      entations as achieved through application of
      said manipulative force thereto.
’358 patent, col. 6, lines 7–56. Claim 2, which depends on
claim 1, adds steps requiring a second set of pedicle
screws and a second derotation tool with a second group of
engagement members and a second “handle means.” Id.,
col. 6, line 57, through col. 7, line 15. Claim 3, which
depends on claim 2, adds steps requiring a second spinal
rod. Id., col. 7, line 16, through col. 8, line 11. Claim 4,
which depends on claim 3, adds that the steps of applying
“manipulative force” to the first and second handle means
“are carried out substantially simultaneously to coopera-
tively achieve an amelioration of an aberrant spinal
column deviation condition.” Id., col. 8, lines 12–17.
Claim 5 adds the same requirement to claim 2 (on which
it depends). Id., col. 8, lines 18–23.
    The asserted claims of the ’121 patent are system
claims 2–4. Claim 2, an independent claim, reads:
   2. A system for aligning vertebrae in the amelio-
   ration of aberrant spinal column deviation condi-
   tions comprising:
      a first set of pedicle screws, each pedicle screw
      having a threaded shank segment and a head
      segment; and
      a first pedicle screw cluster derotation tool, said
      first pedicle screw cluster derotation tool hav-
      ing a first handle means for facilitating simul-
      taneous application of manipulative forces to
6                                BARRY v. MEDTRONIC, INC.

    said first set of pedicle screws and a first group
    of three or more pedicle screw engagement
    members which are mechanically linked with
    said first handle means, said first handle
    means having a handle linked to each pedicle
    screw engagement member of the first group of
    three or more pedicle screw engagement mem-
    bers and a linking member to join together the
    handles linked to the pedicle screw engagement
    members, wherein the handle means is config-
    ured to move simultaneously each pedicle screw
    engagement member; wherein each pedicle
    screw engagement member is configured to en-
    gage respectively with said head segment of
    each pedicle screw of said first set of pedicle
    screws; and wherein each pedicle screw en-
    gagement member is configured to transmit
    manipulative forces applied to said first handle
    means to said head segment of each pedicle
    screw of said first set of pedicle screws;
    a second set of pedicle screws, each pedicle
    screw having a threaded shank segment and a
    head segment;
    a second pedicle screw cluster derotation tool,
    said second pedicle screw cluster derotation tool
    having a second handle means for facilitating
    simultaneous application of manipulative forces
    to said second set of pedicle screws and a sec-
    ond group of three or more pedicle screw en-
    gagement members which are mechanically
    linked with said second handle means, said
    second handle means having a handle linked to
    each pedicle screw engagement member of the
    second group of three or more pedicle screw en-
    gagement members and a handle linking mem-
    ber to join together the handles linked to the
BARRY v. MEDTRONIC, INC.                                 7

      pedicle screw engagement members, wherein
      the handle means is configured to move simul-
      taneously each pedicle screw engagement
      member; wherein each pedicle screw engage-
      ment member is configured to engage respec-
      tively with said head segment of each pedicle
      screw of said second set of pedicle screws; and
      wherein each pedicle screw engagement mem-
      ber is configured to transmit manipulative forc-
      es applied to said second handle means to said
      head segment of each pedicle screw of said sec-
      ond set of pedicle screws;
      a cross-linking member that links the first
      handle means to the second handle means.
’121 patent, col. 7, line 57, through col. 8, line 45. The
parties have highlighted the “cross-linking member”
element in identifying the advance of the ’121 patent
claims over those of the ’358 patent. Claim 3, which
depends on claim 2, and claim 4, which depends on claim
3, add requirements that have had no material role in the
arguments made to this court. Id., col. 8, lines 46–58.
                            B
    The following facts form the core of the background
needed to understand the issues before us. Dr. Barry
began working in late 2002 or early 2003 on trying to link
derotation components (which grab screws in vertebrae to
move the vertebrae) of devices for ameliorating spinal
column deviation conditions. During 2003 he worked
with a sales representative from the DePuy medical-
device company, Mr. Pfefferkorn, to adjust standard
DePuy tools for Dr. Barry’s purposes and in accordance
with Dr. Barry’s ideas. Dr. Barry also spoke about his
ideas with representatives from another company, Spine-
Vision. By July 2003, Dr. Barry had a tool that allowed
8                                   BARRY v. MEDTRONIC, INC.

him to link the        screw-grabbing,    vertebrae-moving
wrenches together.
    Dr. Barry used that tool in three surgeries—on Au-
gust 4, August 5, and October 14. Dr. Barry testified,
without contradiction by any evidence the jury had to
credit, that the three surgeries represent the three most
common types of scoliosis-caused spinal deviation condi-
tions that surgeons typically see. Between August 2003
and January 2004, the patients in those surgeries re-
turned to Dr. Barry several times for follow-up appoint-
ments. During the follow-up appointments, Dr. Barry
viewed x-rays of the patients’ spines, after they had been
able to stand up and walk following the three-month
acute phase of recovery, to determine if the curvature
conditions had been successfully ameliorated by the
surgery.
     According to Dr. Barry’s testimony at trial, it was only
in January 2004, after the three-month follow-up for the
October 14, 2003 surgery, that he felt confident that his
invention functioned for its intended purpose and was
ready to publicize it in a professional forum. J.A. 1161–
65, 1195–96. He prepared an abstract summarizing the
development of his methods and submitted it, by Febru-
ary 1, 2004, for inclusion in the materials to be presented
at a July 2004 International Meeting of Advanced Spinal
Techniques—the selection committee for which accepted
it in April. On December 30, 2004, he filed the applica-
tion for what issued as the ’358 patent, making December
30, 2003, the critical date for that patent for purposes of
the public-use and on-sale bar issues under 35 U.S.C.
§ 102(b) (2002). 1

    1   We refer throughout this opinion to the Title 35
provisions in effect before the changes made by the
Leahy-Smith America Invents Act (AIA), Pub. L. No. 112-
BARRY v. MEDTRONIC, INC.                                   9

    Around the same time, Dr. Lawrence Lenke, a sur-
geon who works with Medtronic, was also working on a
spinal derotation project. His work began in 2002. Med-
tronic contends that Dr. Lenke, through that work, was a
prior inventor and that Dr. Barry’s patents are therefore
invalid under 35 U.S.C. § 102(g).
    By 2006, Medtronic introduced its Vertebral Column
Manipulation (VCM) kit, which is used in conjunction
with Medtronic’s CD Horizon Legacy and Solera spinal-
surgery systems. Dr. Barry alleges that surgeons’ use of
that combination infringes the asserted claims of the two
patents at issue and that Medtronic has induced such
infringement through its extensive training materials and
instructions relating to its VCM kit. As to the latter,
instructions appear on the lid of each kit. Medtronic
employees have trained surgeons in how to use the VCM
kit. Medtronic has included instructions for using the
VCM kit in surgical guides, which Dr. Barry’s expert, Dr.
Walid Yassir, testified Medtronic “put . . . out all of the
time.” J.A. 1782. And Dr. Lenke testified that he used
the VCM kit when performing derotations, even after
2010, the year the ’358 patent issued.
     In this case, the jury found for Dr. Barry, and specifi-
cally did so on the key issues contested by Medtronic in
this appeal—involving whether Dr. Barry’s ’358 invention
was in public use or on sale before December 30, 2003;
whether Dr. Lenke was a prior inventor for both patents;
and whether, and to what extent, Medtronic induced
infringement. As relevant here, the jury awarded Dr.
Barry $15,095,970 for domestic infringement of the ’358
patent and $2,625,210 for domestic infringement of the

29, 125 Stat. 284 (2011), took effect. As the parties agree,
the pre-AIA provisions apply here.
10                                 BARRY v. MEDTRONIC, INC.

’121 patent. J.A. 135. 2 The district court denied Med-
tronic’s post-trial challenges regarding induced infringe-
ment, Barry, 230 F. Supp. 3d at 640–47; domestic in-
infringement damages, id. at 650–51; invalidity under
§ 102(b), id. at 653–59; and invalidity under § 102(g), id.
at 659–63. The district court also rejected Medtronic’s
charge of inequitable conduct by Dr. Barry in his interac-
tions with the Patent and Trademark Office, based on an
admitted mistake in identifying Figure 6 in both patents,
finding absent the intent required for unenforceability on
that ground in a case like this. Inequitable Conduct Op.
at 797–98.
    On appeal, Medtronic raises issues involving the § 102
statutory bars as to the ’358 patent, Br. of Appellant at
26–41; inequitable conduct as to both patents, id. at 44–
48; prior invention as to both patents, id. at 48–58; and
induced infringement and associated damages as to both
patents, id. at 58–67 (infringement), 67–69 (damages).
We have jurisdiction under 28 U.S.C. § 1295(a)(1).
                             II
     We review the denial of judgment as a matter of law
de novo, and we review the denial of a new trial as well as
rulings on jury instructions for abuse of discretion. i4i
Ltd. P’ship v. Microsoft Corp., 598 F.3d 831, 841 (Fed. Cir.
2010) (following Fifth Circuit law), aff’d on other issues,
564 U.S. 91 (2011). We review evidentiary rulings for an
abuse of discretion. Summit 6, LLC v. Samsung Elecs.

     2  The district court eliminated non-domestic in-
fringement and damages from the judgment, a ruling not
on appeal here. Barry, 230 F. Supp. 3d at 647–49. The
court also enhanced the domestic damages by twenty
percent (while denying Dr. Barry attorney’s fees), a ruling
not on appeal here. Enhancement Op. at 111, 119; see
J.A. 309 (final judgment).
BARRY v. MEDTRONIC, INC.                                 11

Co., 802 F.3d 1283, 1294–95 (Fed. Cir. 2015) (following
Fifth Circuit law).
                             A
    We begin with Medtronic’s argument for judgment as
a matter of law that the ’358 patent’s asserted claims are
invalid under § 102(b)’s statutory bar on patenting of
inventions in “public use” in the United States more than
one year before the application for the patent was filed.
Here, the application was filed on December 30, 2004, so
the critical date for an invalidating domestic public use is
December 30, 2003. We reject Medtronic’s challenge.
    “The public use bar is triggered where, before the crit-
ical date, the invention is in public use and ready for
patenting.” Polara Eng’g Inc v. Campbell Co., 894 F.3d
1339, 1348 (Fed. Cir. 2018) (emphasis added) (internal
quotation marks omitted); see also Pfaff v. Wells Elecs.,
Inc., 525 U.S. 55, 67 (1998); Invitrogen Corp. v. Biocrest
Mfg., L.P., 424 F.3d 1374, 1379 (Fed. Cir. 2005). “[T]he
determination of whether a patent is invalid for public
use is a question of law that we review de novo,” but “the
disputed facts found to support that determination are
reviewed for substantial evidence.” Polara, 894 F.3d at
1348; Manville Sales Corp. v. Paramount Sys., Inc., 917
F.2d 544, 549 (Fed. Cir. 1990). “We treat the jury’s ver-
dict of no invalidating public use as a resolution of all
genuinely disputed underlying factual issues in favor of
the verdict winner”—here, Dr. Barry. Polara, 894 F.3d at
1348 (internal quotation marks omitted).
    We discuss “ready for patenting” first, then “in public
use.” We conclude that Medtronic’s § 102(b) public-use
challenge fails on two grounds, which are substantively
related. First, the invention was not ready for patenting
before the critical date. Second, there was no public use
except for an experimental use, and “[p]roof of experi-
mental use serves as a negation of the statutory bars,”
Polara, 894 F.3d at 1348 (internal quotation marks omit-
12                                 BARRY v. MEDTRONIC, INC.

ted); see New Railhead Mfg., L.L.C. v. Vermeer Mfg. Co.,
298 F.3d 1290, 1297–98 (Fed. Cir. 2002); EZ Dock, Inc. v.
Schafer Sys., Inc., 276 F.3d 1347, 1352 (Fed. Cir. 2002).
     We place our discussion of experimental use within
our discussion of the “public use” element. This place-
ment fits the facts that commercial exploitation may
sometimes satisfy that element, Invitrogen, 424 F.3d at
1380, and “[t]he law has long recognized the distinction
between inventions put to experimental use and products
sold commercially,” Pfaff, 525 U.S. at 64; id. at 64–65
(discussing Elizabeth v. American Nicholson Pavement
Co., 97 U.S. 126, 133–37 (1877)). But this placement is
not inevitable: we have observed that “evidence of exper-
imental use may negate either the ‘ready for patenting’ or
‘public use’ prong [of the public-use-bar standard]” and
“recogniz[ed] an overlap of the experimental use negation
and the ready for patenting standard.” Invitrogen, 424
F.3d at 1379–80 (citing EZ Dock, 276 F.3d at 1352). The
overlap is reflected in the fact that the timing of
knowledge that the invention will “work for its intended
purpose” is important to both experimental use and
readiness for patenting. Polara, 894 F.3d at 1348 (de-
scribing such an inquiry for both the “ready for patenting”
and “experimental use” standards); see EZ Dock, 276 F.3d
at 1356–57. In any event, whatever the best doctrinal
organization, experimental use negates invalidity under
the public use bar. We discuss both readiness for patent-
ing and experimental use because they are related and
because the dissent, agreeing with Medtronic about the
first, addresses the second to complete its reasoning to
support its conclusion of invalidity under § 102(b). 3

     3 The dissent proposes several changes to the legal
standards stated in governing case law, such as a change
to impose a (high) burden of persuasion on the patent
owner to establish experimental use. Dissent at 14–19.
BARRY v. MEDTRONIC, INC.                                  13

                             1
     The jury could reasonably find facts that support re-
jection of Medtronic’s contention that Dr. Barry’s ’358
invention was ready for patenting before December 30,
2003. Medtronic’s contention required it to prove that,
before that date, the method was “‘shown or known to
work for its intended purpose.’” Polara, 894 F.3d at 1348
(quoting Helsinn Healthcare S.A. v. Teva Pharm. USA,
Inc., 855 F.3d 1356, 1371 (Fed. Cir. 2017), cert. granted on
a different issue, 138 S. Ct 2678 (2018)); see Electromotive
Div. of Gen. Motors Corp. v. Transp. System Div. of Gen.
Elec. Co., 417 F.3d 1203, 1211 (Fed. Cir. 2005); Manville,
917 F.2d at 550–51. But there is substantial evidence
that Dr. Barry’s invention was not ready for patenting
until January 2004 because the final follow-up from the
October surgery was reasonably needed for the determi-
nation that the invention worked for its intended purpose.
    This court has long held that “the Supreme Court’s
‘ready for patenting test’” from Pfaff, involving the on-sale
bar, also “applies to the public use bar under § 102(b).”
Invitrogen, 424 F.3d at 1379. Medtronic accepts in this
appeal that, to show readiness for patenting, it had to
show (a) a reduction to practice or (b) drawings or descrip-
tions enabling an ordinarily skilled artisan to practice the
invention. Pfaff, 525 U.S. at 67–68. 4 Here, Medtronic’s

Medtronic has not argued for such changes. We follow
existing case law. We also note that we see nothing in the
dissent’s proposed changes that would alter our § 102(b)
result—at the least on the sufficient ground that Med-
tronic failed to establish readiness for patenting.
    4    The dissent states that readiness for patenting
might be shown in some other way. Dissent at 7–9. We
have no such alternative before us. Reduction to practice
and enabling drawings or descriptions are the sole bases
on which Medtronic argues for readiness for patenting.
14                                  BARRY v. MEDTRONIC, INC.

ability to support judgment as a matter of law in its favor
under that test depends on its succeeding under the
reduction-to-practice alternative. 5
    Under the test for a reduction to practice, the chal-
lenger must show that “the inventor (1) constructed an
embodiment or performed a process that met all the
limitations and (2) determined that the invention would
work for its intended purpose.” In re Omeprazole Patent
Litig., 536 F.3d 1361, 1373 (Fed. Cir. 2008) (internal
quotations omitted). What testing was in order to deter-
mine whether an invention would work for its intended
purpose is one of the subsidiary fact questions underlying
a determination of whether an invention was in public
use. See Z4 Techs., Inc. v. Microsoft Corp., 507 F.3d 1340,
1352 (Fed. Cir. 2007) (“Because the necessity and suffi-
ciency of such testing [of an invention to determine if it
will work for its intended purpose] are factual issues,

Br. of Appellant at 29–34. The jury instructions, not
challenged here, are similarly limited. J.A. 158–61.
    5    On appeal, Medtronic also points to drawings pre-
pared in November 30, 2003, by a device company, Spine-
Vision, based on conversations with Dr. Barry, and argues
that the drawings show that “prior to the critical date the
inventor [Dr. Barry] had prepared drawings or other
descriptions of the invention that were sufficiently specific
to enable a person skilled in the art to practice the inven-
tion.” Pfaff, 525 U.S. at 67–68 (footnote omitted). But
Medtronic identifies no expert testimony making the
necessary enablement showing. The jury could reasona-
bly find that Medtronic failed to prove that descriptions
by Dr. Barry (leading to the SpineVision-prepared draw-
ings of devices), or even the drawings, enabled a person of
ordinary skill in the art to practice the surgical-procedure
claims. We therefore limit our discussion in text to Med-
tronic’s argument based on reduction to practice.
BARRY v. MEDTRONIC, INC.                                  15

substantial evidence . . . will suffice to support the jury’s
verdict.”); Slip Track Sys., Inc. v. Metal-Lite, Inc., 304
F.3d 1256, 1268 (Fed. Cir. 2002) (“[W]e leave to the fact
finder the determination of whether testing was necessary
. . . or whether the mere construction of the First Proto-
type, in and of itself, was enough to demonstrate to one of
skill in the art that the invention would work for its
intended purpose without any testing.”); Seal-Flex, Inc. v.
Athletic Track & Court Const., 98 F.3d 1318, 1324 (Fed.
Cir. 1996) (“The trier of fact must determine whether the
invention was completed and known to work for its in-
tended purpose . . . .”). 6

    6    Pfaff supports the “intended purpose” standard in
several ways. In a footnote, see 525 U.S. at 57 n.2, Pfaff
quotes the statement in Corona Cord Tire Co. v. Dovan
Chemical Corp., 276 U.S. 358, 383 (1928), that “[a] pro-
cess is reduced to practice when it is successfully per-
formed.”      What “successfully” means in Corona is
achieving the purpose of accelerating the curing of rubber,
as detailed extensively in Corona and summarized just
before the “successfully performed” language—“It was the
fact that it would work with great activity as an accelera-
tor that was the discovery, and that was all, and the
necessary reduction to use is shown by instances making
clear that it did so work, and was a completed discovery,”
id. at 382–83 (emphasis added)—a summary that the
Court quoted in Pfaff, 525 U.S. at 66 n.12. The “intended
purpose” standard is also reflected in Pfaff’s reliance, in
its rationale leading to the “ready for patenting” standard,
on the statement in Elizabeth that a public use does not
include an inventor’s “bona fide effort to bring his inven-
tion to perfection, or to ascertain whether it will answer
the purpose intended,” Elizabeth, 97 U.S. at 137 (emphasis
added), which was quoted in Pfaff, 525 U.S. at 64–65.
That reliance reflects the intertwining, as opposed to any
16                                  BARRY v. MEDTRONIC, INC.

    Here, Medtronic relied on the August and October
2003 surgeries as reductions to practice that immediately
proved that the claimed invention of the ’358 patent
would work for its intended purpose. But the evidence
allows a reasonable finding that Dr. Barry did not know
that his invention would work for its intended purpose
until January 2004, when he completed the follow-ups on
those surgeries, which were on three patients who fairly
reflected the real-world range of application of the in-
ventive method.
    We have already noted the evidence that the three
surgeries involved “the three most common[] curve types
of scoliosis” seen by surgeons, J.A. 1195, and that it was
not until January 2004 that Dr. Barry completed the
standard-practice follow-up on the third patient, at which
point the three-month acute phase of recovery was over
and the patient could stand up and walk. We also have
noted Dr. Barry’s testimony that only then did he con-
clude that the surgical method would work for its intend-
ed purpose, testimony confirmed by the fact that only
then did he write up his development work for publication
in a professional forum.
    The record contains further supporting evidence. Dr.
Lenke noted the range of scoliosis conditions. J.A. 2644.
Evidence from several sources confirmed that, to evaluate
the success of a spinal-deviation correction, it is important
for the surgeon to evaluate the patient after some time
has elapsed following the surgery, particularly once the
patient can stand. See J.A. 1159–60, 1190–95, 1372,
5406, 5417, 13016. Dr. Barry’s expert testified that “you
know nominally if you have performed a correction of the

clean separation, of experimental use and reduction to
practice standards, which is further reinforced in a later
footnote in Pfaff, 525 U.S. at 66 n.12.
BARRY v. MEDTRONIC, INC.                                  17

spine”—agreeing to the “some amelioration” characteriza-
tion by Medtronic’s counsel only to that limited extent—
and then immediately explained, starting in the same
answer, that what happened afterward was crucial:
“when the patient stands up, there are some changes that
happen over time.” J.A. 1959–60. As a result, he added,
although “normally you can see the straightening” at the
time of the surgery, “follow-up is absolutely required to
determine that it lasts,” J.A. 2906, and the follow-up
appointments allowed Dr. Barry to conclude, “‘[o]kay, this
thing is holding up’ and . . . ‘[n]ow I know I’ve got a meth-
od that works,’” J.A. 2899. Both Dr. Barry and his expert
indicated that at least that amount of follow-up is not just
prudent but consistent with standards for peer-reviewed
publications reporting new techniques.
    That evidence suffices for the jury to have rejected
Medtronic’s contention that Dr. Barry is charged with
knowing that the surgical technique worked for its in-
tended purpose immediately upon completion of the
surgical operation—at least the last operation, in October
2003. The evidence is not limited to Dr. Barry’s own
testimony, as just indicated. And credibility assessments,
within a broad range, are for the factfinders, especially
when they have seen the witnesses live, as the jurors in
this case did. See, e.g., Cooper v. Harris, 137 S. Ct. 1455,
1474 (2017); Perry v. New Hampshire, 565 U.S. 228, 237
(2012); Kansas v. Ventris, 556 U.S. 586, 594 n.* (2009);
Reeves v. Sanderson Plumbing Prods., Inc., 530 U.S. 133,
150 (2000); Aetna Life Ins. Co. v. Ward, 140 U.S. 76, 88
(1891); Power Integrations, Inc. v. Fairchild Semiconduc-
tor Int’l, Inc., 843 F.3d 1315, 1341 (Fed. Cir. 2016); Co-
mark Comm’ns, Inc. v. Harris Corp., 156 F.3d 1182, 1192–
93 (Fed. Cir. 2000). On the evidence in this case, the jury
could readily credit the testimony of Dr. Barry—who has
extensive medical experience and day-to-day professional
responsibility for patient health and safety—about what
evaluation was reasonably necessary for a prudent de-
18                                  BARRY v. MEDTRONIC, INC.

termination that his technique worked for its intended
purpose.
    To the extent that Medtronic contends, and the dis-
sent concludes, that the patent claims compel narrowing
the “intended purpose” determination to a single surgery,
or even two surgeries, assessed for success immediately
upon its completion, we disagree. The claims do not limit
the intended purpose in that way. They are not limited to
a particular type of curvature correction. Nor do they
indicate that the intended purpose is limited to observing
a straightening at the completion of surgery, without
regard to the correction lasting so as to improve the
patient’s health. To the contrary, the preamble to the
independent claim calls for “the amelioration of aberrant
spinal column deviation conditions,” ’358 patent, col. 6,
lines 8–9, which Medtronic argues is the intended pur-
pose, Br. of Appellant at 30. See also ’358 patent, col. 3,
lines 10–34 (specification statement of first four objects of
the invention using materially the same language). In a
ruling not disputed on appeal, the district court concluded
that the phrase would be given its “normal, customary
meaning,” without further construction, and that no
indefiniteness problem would result because, in this
medical context, a skilled artisan, focused on “benefit to a
patient,” would understand the scope of the phrase. J.A.
33. That common-sense approach to identifying the
intended purpose is rooted in the preamble claim lan-
guage as well as the specification. And it is properly
understood, consistent with the specification’s background
discussion of patients’ conditions beyond the end of sur-
gery, ’358 patent, cols. 1–2 (discussing patient health over
time), as looking past the time of a surgery to evaluate
the improvement in patients’ conditions and allowing the
withholding of judgment about the technique reliably
working until follow-up on a small but representative
BARRY v. MEDTRONIC, INC.                                19

range of “deviation conditions” surgeons would regularly
encounter. 7
    The “intended purpose” need not be stated in claim
limitations that define the claim scope. Even in this case,
the claim language that Medtronic treats as identifying

   7     The dissent suggests that at most two surgeries,
not three, were needed for the plural “conditions.” Dis-
sent at 12–13. But Medtronic has not meaningfully
presented, let alone supported, such a rationale for rever-
sal. Only a single sentence in Medtronic’s opening brief,
where arguments must be made, is of even possible rele-
vance. After reciting the district court’s reliance on Dr.
Barry’s testimony that “he wanted to follow up with his
patients three months after the surgery,” citing J.A. 215,
1196, Medtronic said: “That reasoning fails even on its
own terms: three months after surgeries on August 4 and
5, 2003, would mean reduction to practice in early No-
vember, which is still nearly two months before the De-
cember 30, 2003 critical date.” Br. of Appellant at 30,
lines 6–9. If the dissent’s point is one about the claim
preamble’s plural language, Medtronic’s sentence says
nothing about that. If the dissent’s point is a medical-
judgment point about the need for three rather than two
surgeries, Medtronic’s sentence is doubly deficient. The
testimony Medtronic says it is answering is not about
three versus two, but merely about the length of follow-up
time, as confirmed by the citations to J.A. 215, 1196. In
any event, and decisively, a medical-judgment point must
be supported by evidence, but Medtronic’s sentence is
unaccompanied by any citation to the record at all. Spe-
cifically, there is no citation to evidence contrary to Dr.
Barry’s testimony as a factual matter about the need for
follow-ups of three surgeries, much less evidence that
compelled a determination in Medtronic’s favor on this
point.
20                                  BARRY v. MEDTRONIC, INC.

the “intended purpose” is preamble language that, it is
undisputed here, is not limiting, i.e., it does not state a
requirement that must be proved to establish infringe-
ment. See J.A. 152 (unchallenged jury instruction). The
case law cited by the dissent (at 10–11) looks to the claims
and specification as a whole for guidance, without declar-
ing strict requirements even as to those sources. We note
that it is hardly surprising that intended purpose need
not be stated in claim limitations, given that one typical
way of claiming is simply to define the physical steps of
the process, or the physical elements of a product, without
building functional or purpose language into the claim
limitations at all. See, e.g., In re Schreiber, 128 F.3d 1473,
1478 (Fed. Cir. 1997) (explaining that “[a] patent appli-
cant is free to recite features of an apparatus either struc-
turally or functionally” but that the latter choice presents
distinctive risks) (emphasis added).
    Case law confirms this approach. For example, in Co-
rona Cord, the Supreme Court, for its reduction-to-
practice analysis, inferred the accelerate-curing purpose
from the specification. And it described the main claims
at issue (No. 1,411,231, claims 4, 8, and 12) as stating
simple process steps without any reference to that pur-
pose. 276 U.S. at 366.
     In Manville, the patentee designed a light pole as-
sembly that could be easily raised and lowered. 917 F.2d
at 547–48. None of the claims included language about
the light pole being durable in different weather condi-
tions, but we determined that the patentee’s testing of the
invention “under wind, cold and corrosive atmospheric
conditions” did not qualify as a public use because “[p]rior
to its testing in the winter environment, there really was
no basis for confidence by the inventor that the invention
would perform as intended, and hence no proven inven-
tion to disclose.” Id. at 550. It was not necessary for the
patent to claim durability in order for durability to be
part of the patent’s intended purpose because a certain
BARRY v. MEDTRONIC, INC.                                 21

function can be “inherent to the purpose of an invention,”
necessitating further testing even when that inherent
purpose is not claimed. Id. at 551.
    Similarly, in Polara, we agreed with Polara that it
“needed to test the claimed invention at actual crosswalks
of different sizes and configurations and where the proto-
type would experience different weather conditions to
ensure that the invention would work for its intended
purpose.” 894 F.3d at 1349. The patent in that case was
for a control system that would alert pedestrians when it
was safe to cross the street. Id. at 1344. The claim lan-
guage did not include limitations about the weather
conditions or the size of the crosswalk, id., but we deter-
mined that the inventor could not know if the invention
worked for its intended purpose until it had been tested in
a variety of settings where it would operate, id. at 1349.
Testing an invention in practical situations was part of
the determination of whether it was ready for patenting.
    In Honeywell International v. Universal Avionics Sys-
tems, we likewise recognized that an invention might not
be ready for patenting until the inventor ascertains how
that invention will function in practical circumstances.
Honeywell Int’l Inc. v. Universal Avionics Systems Corp.,
488 F.3d 982 (Fed. Cir. 2007). Honeywell was developing
a terrain warning system for airplanes to address a
problem in the prior art, whose ground proximity detec-
tors could not detect sudden changes in terrain. Id. at
987. Honeywell’s system “compare[d] the aircraft’s posi-
tion with an on-board digitized map of the earth’s terrain
and man-made obstacles.” Id. at 987–88. Because there
was evidence that Honeywell negotiated to sell its system
to a customer, raising an issue under the on-sale bar, we
had to determine if the invention was ready for patenting
under the Pfaff test for that statutory bar. Id. at 997. We
held that Honeywell’s system was not ready for patenting
before the critical date because the sale and integration of
the system in real planes flown by human pilots “were a
22                                 BARRY v. MEDTRONIC, INC.

part of Honeywell’s program to determine that the inven-
tion worked for its intended purpose.” Id. at 996. In
short, Honeywell’s determination that the system worked
for its intended purpose was reasonably dependent on
completion of a range of tests in a variety of real-world
situations in which the system would be used. 8
    In TP Laboratories, Inc. v. Professional Positioners,
Inc., 724 F.2d 965 (Fed. Cir. 1984), moreover, we con-
firmed the common-sense proposition that, for medical
procedures, follow-up appointments can be necessary to
determine when an invention is performing its intended
purpose. The invention at issue was a means of correct-
ing irregularities in teeth. Id. at 972. We determined
that the inventor could not have immediately assessed
after implantation whether the device was working for its
intended purpose; therefore, it was reasonable for the
doctor to continue to follow patients and test the inven-
tion on several patients before determining if it was
working for the purpose intended. Id.
    The three types of curvature addressed by Dr. Barry’s
three surgeries are analogous to the different weather
conditions in Manville and Polara, the different crosswalk
dimensions in Polara, and the different types of terrain in
Honeywell. And Dr. Barry’s reliance on follow-up ap-
pointments is analogous to the role of follow-up appoint-
ments in TP Laboratories. We therefore affirm the
determination that the claimed ’358 patent invention was
not ready for patenting before the critical date.

     8  In the related context of experimental use, we
have likewise recognized that sometimes testing for a
property can fall outside the statutory bars even if that
property is not required by a claim limitation. See Elec-
tromotive, 417 F.3d at 1212 (first citing Manville as well
as EZ Dock, 276 F.3d at 1353, then citing Seal-Flex, 98
F.3d at 1320).
BARRY v. MEDTRONIC, INC.                                23

                            2
    Although the foregoing discussion suffices to affirm
the rejection of Medtronic’s invalidity challenge under
§ 102(b)’s public-use bar, we think it worthwhile to ad-
dress Medtronic’s contentions regarding the other element
of the test of invalidity under the public-use bar: whether
the invention was “in public use.” We conclude that
Medtronic also fails under this element.
     Medtronic sought to establish this element by show-
ing that the invention was accessible to the public and
that it was commercially exploited. We conclude, howev-
er, that the evidence permitted a reasonable finding that
Dr. Barry’s ’358 patent invention was not accessible to the
public before the critical date. We also conclude that the
asserted acts of commercial exploitation, namely, the
August and October 2003 surgeries, come within the
experimental-use exception.
                             i
    In assessing accessibility to the public, we have fo-
cused on several underlying facts: “the nature of the
activity that occurred in public; the public access to and
knowledge of the public use; [and] whether there was any
confidentiality obligation imposed on persons who ob-
served the use.” Dey, L.P. v. Sunovion Pharm., Inc., 715
F.3d 1351, 1355 (Fed. Cir. 2013). Here, the alleged public
use consisted of Dr. Barry’s surgeries. But there is sub-
stantial evidence that Dr. Barry’s surgeries were not
exposed or accessible to the public.
    Unlike in the classic case of Egbert v. Lippmann, 104
U.S. 333, 335 (1881), the inventor here did not relinquish
control of his invention. Dr. Barry was the only one who
actually practiced the invention, i.e., performed the sur-
gery using the claim-required manipulation of linked
derotators. And while other people were present in the
operating room—an anesthesiologist, two assistant physi-
24                                 BARRY v. MEDTRONIC, INC.

cians, a scrub technician, a neurophysiologist, a circulat-
ing nurse, and an equipment representative—there was
sufficient evidence for the jury to find facts establishing
that the technique was not accessible to the public
through those people.
    The evidence showed that very few of the people in
the operating room had a clear view of the surgical field,
where Dr. Barry was using his invention, because they
were either not permitted near the sterile field or because
there was a drape blocking the view. More dispositively,
although sometimes (as in Egbert) even a limited disclo-
sure can make an invention accessible to the public, see
Dey 715 F.3d at 1355–56, an accessibility determination
may be rejected where the evidence establishes a suffi-
cient obligation of confidentiality, which can be implied
rather than express. Id. at 1357; Delano Farms Co. v.
Cal. Table Grape Comm’n, 778 F.3d 1243, 1249 (Fed. Cir.
2015) (“[D]emonstration of a prototype to ‘friends and
colleagues’ was not invalidating because the evidence
supported the existence of ‘a general understanding of
confidentiality.’”); Invitrogen, 424 F.3d at 1381 (“[T]his
court has determined that a use before the critical period
was not public even without an express agreement of
confidentiality.”). Here, the jury could find that those in
the operating room were under an implied duty of confi-
dentiality covering at least the tools and techniques used.
See J.A. 1311, 1167–68, 1679, 2388–89. These confidenti-
ality understandings suffice to support the jury’s finding
of no public accessibility.
                            ii
     For commercial exploitation, as for public accessibil-
ity, Medtronic relies on the August and October surgeries.
It rightly recognizes that “an inventor’s own prior com-
mercial use, albeit kept secret, may constitute a public
use or sale under § 102(b), barring him from obtaining a
patent.” Woodland Tr. v. Flowertree Nursery, Inc., 148
BARRY v. MEDTRONIC, INC.                                  25

F.3d 1368, 1370 (Fed. Cir. 1998); see TP Labs., 724 F.2d at
972. And it points out, correctly, that Dr. Barry was
compensated for the three surgeries in which he used his
invention. It also cites precedents to support its conten-
tion that a determination of commercial exploitation
would not be defeated simply because Dr. Barry charged
his standard fee for the surgeries, not an extra amount
reflecting use of the inventive method. See, e.g., Cargill,
Inc. v. Canbra Foods, Ltd., 476 F.3d 1359, 1369, 1370
(Fed. Cir. 2007); In re Kollar, 286 F.3d 1326, 1333 (2002)
(citing Scaltech, Inc. v. Retec/Tetra, LLC, 269 F.3d 1321,
1328 (Fed. Cir. 2001)) (relying on “[a]ctually performing
the process itself for consideration”); Application of Dybel,
524 F.2d 1393, 1401 (CCPA 1975); Application of Joss-
erand, 188 F.2d 486, 493–94 (C.C.P.A. 1951). But cf. TP
Labs., 724 F.2d at 968, 973 (finding no commercial exploi-
tation, in part, because “the inventor[s] made no extra
charge for fitting the three patients” with the invention
and “followed ‘their’ regular practice of setting a fixed
total fee”).
    But regardless of the foregoing, the August and Octo-
ber surgeries come within the experimental-use exception.
An inventor’s use, while public in one sense, will not be
considered a statutory public use if the use was experi-
mental. Electromotive, 417 F.3d at 1211; City of Eliza-
beth, 97 U.S. at 134–35 (“The use of an invention by the
inventor himself, or of any other person under his direc-
tion, by way of experiment, and in order to bring the
invention to perfection, has never been regarded as [a
public] use. . . . [Testing an invention in a building even
with the doors open] is not a public use, within the mean-
ing of the statute, so long as the inventor is engaged, in
good faith, in testing its operation. He may see cause to
alter it and improve it, or not. His experiments will
reveal the fact whether any and what alterations may be
necessary.”). “[I]n the context of a public use bar, evi-
dence of experimental use may negate either the ‘ready
26                                  BARRY v. MEDTRONIC, INC.

for patenting’ or ‘public use’ prong.” Invitrogen, 424 F.3d
at 1379–80. “A use may be experimental if its purpose is:
‘(1) [to] test claimed features of the invention or (2) to
determine whether an invention will work for its intended
purpose—itself a requirement of patentability.’” Polara,
894 F.3d at 1348; see Clock Spring, L.P. v. Wrapmaster,
Inc., 560 F.3d 1317, 1327 (Fed. Cir. 2009).
    This court has identified a host of factors that can be
relevant to assessing whether a use is experimental,
including:
     (1) the necessity for public testing, (2) the amount
     of control over the experiment retained by the in-
     ventor, (3) the nature of the invention, (4) the
     length of the test period, (5) whether payment was
     made, (6) whether there was a secrecy obligation,
     (7) whether records of the experiment were kept,
     (8) who conducted the experiment, (9) the degree
     of commercial exploitation during testing, (10)
     whether the invention reasonably requires evalu-
     ation under actual conditions of use, (11) whether
     testing was systematically performed, (12) wheth-
     er the inventor continually monitored the inven-
     tion during testing, and (13) the nature of contacts
     made with potential customers.
Id.; see Allen Eng’g Corp. v. Bartell Indus., Inc., 299 F.3d
1336, 1353 (Fed. Cir. 2002). Many of those considerations
are factual, but “[e]xperimental use is a question of law to
be analyzed based on the totality of the surrounding
circumstances.” Petrolite Corp. v. Baker Hughes Inc., 96
F.3d 1423, 1426 (Fed. Cir. 1996).
    In this case, the evidence—including the evidence al-
ready discussed when addressing “ready for patenting”—
shows that many of the above-recited factors point toward
a conclusion of experimental use. Dr. Barry was not sure
that the device would work on different types of scoliosis,
so he performed surgeries on the three main types. He
BARRY v. MEDTRONIC, INC.                                 27

was not confident that the new procedure was effective
until the January 2004 follow-up appointment for the
third of those surgeries. In the context of this medical
patent, as we have discussed, it is reasonable, to truly
determine whether a method works, to engage in such
testing for a brief time on a small but representative
range of expected circumstances of use and to rely on
follow-up. See TP Labs., 724 F.2d at 972. Dr. Barry
earned no more from the surgeries than he would have
earned had he used prior-art methods; and there is no
basis for finding that he attracted the three customers
because of the new technique—indeed, Medtronic insists
that they did not even know it was being used. 9 In addi-
tion, Dr. Barry was the only one to perform the method
using his device. More generally, he did not surrender
control of the claimed invention before the critical date.
J.A. 1312. He kept control through the expectation of
secrecy binding the other medical professionals present at
the surgeries and the other circumstances that, as ex-
plained above, support the jury’s determination of no
public accessibility. And other people were aware that he
was experimenting, including one doctor, one of the
nurses in the operating room, and a representative of the
DePuy medical-device firm who was helping with the

   9    Contrary to the dissent (at 21–22), this fact reduc-
es the “degree of commercial exploitation,” Clock Spring,
560 F.3d at 1327, in the sense at the heart of the § 102(b)
policy of preventing an overlong period of commercial
exploitation of an invention. Though earning his normal
fees from the three surgeries, Dr. Barry did not “exploit”
his invention as a means to attract the three patients for
those surgeries or to charge more because he used his new
technique. The jury could find that he would have gotten
the same business, and earned the same fee, even if he
had not planned to use or used the inventive process.
28                                  BARRY v. MEDTRONIC, INC.

instrumentation.     See J.A. 1370, 1178–79, 1733–35.
These are all facts that the jury could reasonably find;
considered together, not in isolation from each other, they
weigh in favor of a determination of experimental use.
    Medtronic relies centrally on two factors as pointing
against a finding of experimental use: that Dr. Barry
charged his patients for the surgeries; and that Dr. Barry
did not inform his patients that he was engaged in testing
of his particular technique. The first factor is not by itself
weighty in this case. Receipt of payment, if sufficiently
incidental to an experiment, is not automatically disquali-
fying. See, e.g., Int’l Tooth Crown Co. v. Gaylord, 140 U.S.
55, 62–63 (1891); Allen, 299 F.3d at 1354. The evidence
permitted the jury to find that Dr. Barry earned no more
from the surgeries than he would have earned from using
prior-art methods and did not attract his three patients
based on use of the inventive method. On these facts, his
fee can be viewed as merely incidental to experimental
work—a very limited number of tests, “reasonably neces-
sary” to the experimental purpose, Int’l Tooth Crown, 140
U.S. at 63—if the surgeries are otherwise experimental.
    Medtronic must rely, therefore, on the second factor,
at least when present together with the first. Both cir-
cumstances were present in Sinskey v. Pharmacia Oph-
thalmics, Inc., 982 F.2d 494 (Fed. Cir. 1992), overruled on
other grounds by Pfaff, 525 U.S. 55 (1998), on which
Medtronic heavily relies. Dr. Sinskey was working on an
intraocular lens that would be “implanted in the human
eye to restore or improve the visions of patients who ha[d]
had their natural lens removed because of damage or
disease.” Id. at 496. Between January and February
1980—before the critical date of February 24, 1980—Dr.
Sinskey implanted the lens in eight patients. Id. at 497.
He followed standard hospital procedures and was paid
for the surgery. Id. We determined that the “objective
evidence . . . cut[] heavily against experimental use.” Id.
at 499. We noted that he “charged his usual surgical fee
BARRY v. MEDTRONIC, INC.                                   29

for the operation and a standard price for the implants.”
Id. And we relied on the fact that he “did not inform the
patients that they were being treated with a ‘new’ or
‘experimental’ lens.” Id.
      The facts in Sinskey differ from the facts here in ways
that we think are crucial. First, there was evidence here
that not just Dr. Barry, but others, understood the surger-
ies to be experimental. In Sinskey, there was no such
objective confirmation; and Dr. Sinskey himself, during
his deposition, had stated that he did not consider his
prior uses to be experimental. Id. at 497–98. Second, the
nature of the invention and conduct is critically different
in the two cases. Whereas Dr. Barry’s invention is of a
method, Dr. Sinskey’s patent was for a physical product,
i.e., a lens. Id. at 496 (“The patent is directed to an intra-
ocular lens.”). And when Dr. Sinskey implanted the lens
in a patient, he was surrendering control of his invention,
whereas Dr. Barry did not surrender control of his inven-
tion when he performed the derotation surgeries.
    The experimental-use inquiry asks whether the in-
ventor’s conduct would lead the “‘public’ to reasonably
believe the invention was in the public domain,” Manville,
917 F.2d at 550, and in particular whether there has been
“any use of that invention by a person other than the
inventor who is under no limitation, restriction or obliga-
tion of secrecy to the inventor,” In re Smith, 714 F.2d
1127, 1134 (Fed. Cir. 1983). When Dr. Sinskey surren-
dered control of the invention to another, without explain-
ing that the device was experimental, the public was
entitled to believe that the device was in the public do-
main. That conclusion answered the statutory question
at least in the absence of any objective evidence support-
ing Dr. Sinskey’s litigation claim of experimental use.
    This court stated the principle in LaBounty Mfg., Inc.
v. U.S. Int’l Trade Comm’n: “When sales are made in an
ordinary commercial environment and the goods are
30                                 BARRY v. MEDTRONIC, INC.

placed outside the inventor’s control, an inventor’s secret-
ly held subjective intent to ‘experiment,’ even if true, is
unavailing without objective evidence to support the
contention. Under such circumstances, the customer at a
minimum must be made aware of the experimentation.”
958 F.2d 1066, 1072 (Fed. Cir. 1992) (citation omitted).
That statement ties a demand for a warning of experi-
mentation to at least two premises (which were present in
Sinskey and LaBounty) beyond the “ordinary commercial
environment”—there was no other objective evidence of
experimentation, but merely a subjective inventor belief;
and “the goods [were] placed outside the inventor’s con-
trol.” Id. But both of those premises are missing in the
present case. There is objective evidence of experimenta-
tion, not just a purely subjective intent of Dr. Barry. And
there was no loss of control—a factor that this court has
stressed “is critically important.” Lough v. Brunswick
Corp., 86 F.3d 1113, 1120 (Fed. Cir. 1996). No person left
the operating room with the (method) invention, and no
person learned the method without an obligation of confi-
dentiality. In these circumstances, there was no placing
of the invention in the public domain that is inconsistent
with experimentation.
    Medtronic cites several of our opinions that contain
language that, taken out of context, might be read as
making a necessary requirement for experimental use
that the experimenter inform patients or customers of the
experimental nature of the product. But the statements
should not be taken out of context. Like LaBounty, which
expressly tied the inform-customers statement to placing
a product invention outside the inventor’s control, every
one of those cases in fact involved a device placed into a
patient’s or customer’s control, and out of the inventor’s
control. See, e.g., Electromotive, 417 F.3d at 1213 (focus-
ing on the importance of customer awareness when the
invention is put squarely in the hands and in the control
of the customer); Paragon Podiatry Lab., Inc. v. KLM
BARRY v. MEDTRONIC, INC.                                31

Labs., Inc., 984 F.2d 1182, 1186–87 (Fed. Cir. 1993)
(discussing the importance of communicating with cus-
tomers the experimental nature of orthotic devices placed
in the customer’s shoes); Sinskey, 982 F.2d at 499 (dis-
cussing how Mr. Sinskey fitted the patients with a new
kind of lens); LaBounty, 958 F.2d at 1069–70, 1072 (dis-
cussing the need to inform customers who used the scrap
metal shears that the shears were experimental); In re
Dybel, 524 F.2d at 1394–95, 1401 (discussing how the
inventor’s failure to disclose the experimental nature of
his “load sensing piezoelectric transducer” when he sold it
to a customer was fatal to the inventor’s experimental-use
argument). We have not applied the inform-customer
principle in a context, like the present, involving a meth-
od kept within the inventor’s control. The underlying
logic of the principle does not justify its extension here:
explaining to patients (or their parents or insurers) that
the procedure was experimental was not vital to keeping
it from the public domain.
    The experimental-use exception is properly applied in
light of the recognized mix of § 102(b) policies—permitting
experimental testing, protecting existing public domain
knowledge, limiting extension of the statutory period of
gaining revenues due to the invention, and encouraging
prompt disclosure. See, e.g., Lough, 86 F.3d at 1119–20.
Here, on all the facts the jury could properly find, we
conclude that the surgeries fall within the experimental-
use exception. 10
                            B
    The second asserted § 102(b) ground of invalidity of
the asserted claims of the ’358 patent is the on-sale bar.

   10    We discuss Medtronic’s new-trial challenge to a
jury instruction regarding experimental use in our discus-
sion of the on-sale bar next.
32                                  BARRY v. MEDTRONIC, INC.

“A person shall be entitled to a patent unless . . . the
invention was . . . on sale in this country, more than one
year prior to the date of the application for patent in the
United States[.]” 35 U.S.C. § 102(b) (2002). To be ren-
dered invalid under the on-sale bar, an invention “must
be the subject of a commercial offer for sale” in the United
States and it “must be ready for patenting.” Pfaff, 525
U.S. at 67; see Helsinn Healthcare S.A. v. Teva Pharms.
USA, Inc., No. 17-1229, slip op. at 1, 6 (U.S. Jan. 22,
2019). But experimental use negates applicability of the
on-sale bar, as it does the public-use bar. Polara, 894
F.3d at 1348.
    We have already concluded, in discussing the public-
use bar, that the ’358 patent’s invention was not ready for
patenting before the critical date and that the August and
October 2003 surgeries come within the experimental-use
exception. Those conclusions leave only one aspect of
Medtronic’s on-sale-bar challenge that requires discus-
sion. 11
    Medtronic argues on one ground for a new trial re-
garding experimental use. It challenges a jury instruction
that informed the jury that “there is a difference between
‘experimental use’ in the context of patent law and the
way that the word ‘experiment’ is used in the context of
medicine.” J.A. 160. We reject this challenge.
    Although underlying questions of patent law are mat-
ters of this court’s law, we generally apply regional-circuit
law on the overall standards for setting aside a verdict
because of asserted error in jury instructions. See Kinetic

     11 We need not discuss whether certain pre-critical-
date communications between Dr. Barry and two device
makers, DePuy and SpineVision, would constitute offers
for sale under “traditional contract law principles.” Allen
Eng’g, 299 F.3d at 1352.
BARRY v. MEDTRONIC, INC.                                 33

Concepts, Inc. v. Blue Sky Med. Grp., Inc., 554 F.3d 1010,
1021 (Fed. Cir. 2009); Voda v. Cordis Corp., 536 F.3d
1311, 1328 (Fed. Cir. 2008). The Fifth Circuit asks
whether “the ‘charge as a whole leaves [the court] with
substantial and ineradicable doubt whether the jury [was]
properly guided in its deliberations’ and the challenged
instructions, separately or collectively, ‘affected the out-
come of the case.’” Janvey v. Dillon Gage, Inc. of Dallas,
856 F.3d 377, 388 (5th Cir. 2017).
    The district court’s instruction was not an abuse of
discretion. In light of Medtronic’s suggestions regarding
the impropriety of medical experimentation without
informed consent, it was reasonable for the court to
address potential confusion about borrowing, for § 102(b),
legal standards that govern experiments in quite different
legal contexts. And what the court said on the subject
was both modest and consistent with our holdings. This
court has explained, specifically with regard to testing,
that legal standards in other contexts do not control in the
patent-validity context. Pennwalt Corp. v. Akzona Inc.,
740 F.2d 1573, 1580 (Fed. Cir. 1984) (“The fact that a sale
or use occurs under a regulatory testing procedure, such
as a FIFRA15 experimental use permit, does not make
such uses or sales per se experimental for purposes of 35
U.S.C. § 102(b).” (footnote omitted)); see also Helsinn, 855
F.3d at 1373 (explaining that the standards for FDA
experimentation are different from patent law’s “ready for
patenting” standards); Clock Spring, 560 F.3d at 1328
(explaining that actions and regulations by the Depart-
ment of Transportation did not impact the analysis of
whether the inventor’s use was experimental). The
district court’s jury instruction in this case reasonably
made that point to reduce the potential for a confused
application of § 102(b)’s standards.
34                                 BARRY v. MEDTRONIC, INC.

                             C
     Medtronic’s final invalidity challenge, applicable to
both patents at issue here, is that Dr. Lenke invented the
claimed matter before Dr. Barry, rendering the asserted
claims invalid under 35 U.S.C. § 102(g). “A person shall
be entitled to a patent unless . . . before such person’s
invention thereof, the invention was made in this country
by another inventor who had not abandoned, suppressed,
or concealed it.” 35 U.S.C. § 102(g)(2) (2002). “[P]riority
of invention goes to the first party to reduce an invention
to practice unless the other party can show that it was the
first to conceive the invention and that it exercised rea-
sonable diligence in later reducing that invention to
practice.” Z4 Techs., 507 F.3d at 1352.
    Reduction to practice requires that the inventor prove
that “(1) he constructed an embodiment or performed a
process that met all the limitations . . . and (2) he deter-
mined that the invention would work for its intended
purpose.” Id. Medtronic had the burden of showing by
clear and convincing evidence that Dr. Lenke reduced to
practice first. See id. Reduction to practice is a mixed
question of law and fact. Id. “[W]e must sustain the
jury’s conclusion unless the jury was not presented with
substantial evidence to support any set of implicit find-
ings sufficient under the law to arrive at its conclusion.”
Eli Lilly & Co. v. Aradigm Corp., 376 F.3d 1352, 1362
(Fed.Cir.2004).
    We uphold the jury’s rejection of Medtronic’s § 102(g)
challenge because there is substantial evidence to support
a finding that Dr. Lenke did not reduce the claimed
inventions to practice before February 2006, after Dr.
Barry did so (for both patents at issue here). Weaknesses
in Medtronic’s evidence, including credibility issues,
allowed the jury to reject Medtronic’s assertion that Dr.
Lenke, having worked on linked derotators since 2002,
reduced the Barry-claimed inventions to practice before
BARRY v. MEDTRONIC, INC.                                  35

Dr. Barry did so in 2004. See Barry, 230 F. Supp. 3d at
659–63. At the same time, substantial evidence supports
Dr. Barry’s account of his invention and reduction to
practice before February 9, 2006, including his 2003
surgeries and follow-up appointments, his securing of
assistance from device makers, and his continued work in
2004.
                             D
    Medtronic asserted in the district court that the two
patents are unenforceable because Dr. Barry engaged in
inequitable conduct during patent prosecution in the
PTO. The district court found no such inequitable con-
duct. We affirm that determination.
    “Inequitable conduct is an equitable issue committed
to the discretion of the trial court and is, therefore, re-
viewed by this court under an abuse of discretion stand-
ard.” Energy Heating, LLC v. Heat On-The-Fly, LLC, 889
F.3d 1291, 1299 (Fed. Cir. 2018). Inequitable conduct
here requires a showing of both materiality and intent.
Therasense, Inc. v. Becton, Dickinson & Co., 649 F.3d
1276, 1290 (Fed. Cir. 2011) (en banc). “[W]e review the
district court’s findings of materiality and intent for clear
error.” Regeneron Pharm., Inc. v. Merus N.V., 864 F.3d
1343, 1351 (Fed. Cir. 2017) (quotation marks omitted).
     The basis of the charge of inequitable conduct is Fig-
ure 6 of both patents, which Dr. Barry initially described
incorrectly. Both patents describe Figure 6 as displaying
“a three frame x-ray view showing ‘before and after’ views
of a scoliosis patient who was treated in an investigation-
al procedure using the system and method of the present
invention.” ’358 patent, col. 4, lines 38–41; ’121 patent,
col. 4, lines 44–47. In January 2008, during the initial
prosecution, the examiner requested clearer drawings
than those originally submitted, including the x-rays that
make up Figure 6. J.A. 5077 (“Figures 1-4 and 6-7 are
objected [to] as they are unclear and do not distinctly
36                                 BARRY v. MEDTRONIC, INC.

show features which are pertinent to the understanding of
the disclosed device. New corrected drawings are re-
quired.”). In September 2008, Dr. Barry’s counsel submit-
ted a different set of x-rays for Figure 6. The evidence in
this case indicates that counsel was not aware that,
contrary to the description, the subject of the submitted x-
rays actually was not a patient treated with the inventive
methods, but instead was a patient treated on June 23,
2003, using a method that was not the invention claimed
in the ’358 patent (or the ’121 patent’s follow-on inven-
tion).
    In March 2016, Dr. Barry sought to correct the de-
scription during this litigation. For the ’121 patent, the
PTO allowed the correction, issuing a Certificate of Cor-
rection in August 2016. Dr. Barry simultaneously re-
quested the same correction of the ’358 patent, but the
’358 patent was the subject of an inter partes review
proceeding at the time, so he withdrew the request in
April 2016. Dr. Barry then filed a motion to correct under
37 C.F.R. § 1.323. The Patent Trial and Appeal Board
denied the motion, expressing uncertainty about why the
mistake had happened and why Dr. Barry had taken as
long as he did to ask for the correction. When Dr. Barry
again requested a certificate of correction from the PTO
on May 25, 2017, the PTO granted the request and issued
a Certificate of Correction in June 2017.
    The district court found that there was no intent to
deceive the PTO on the part of Dr. Barry and his counsel.
Inequitable Conduct Op., 245 F. Supp. 3d at 804–06. The
district court found that both Dr. Barry and his counsel
were credible in explaining why the errors occurred,
without any intent to deceive, and why the errors were
not discovered until this litigation. Id. We see no clear
error in the court’s finding that the intent required for
inequitable conduct is absent here. We need not reach the
issue of materiality.
BARRY v. MEDTRONIC, INC.                                  37

                             E
      Medtronic challenges the jury’s finding that Medtron-
ic directly infringed the patents and that it induced others
to infringe. “Whoever actively induces infringement of a
patent shall be liable as an infringer.” 35 U.S.C. § 271(b).
“[I]nducement liability may arise if, but only if, [there is]
. . . direct infringement.” Limelight Networks, Inc. v.
Akamai Techs., Inc., 134 S. Ct. 2111, 2117 (2014) (internal
quotation marks omitted). “The patentee must also show
that the alleged infringer possessed the requisite intent to
induce infringement, which we have held requires that
the alleged infringer knew or should have known his
actions would induce actual infringements.” Eli Lilly &
Co. v. Teva Parenteral Medicines, Inc., 845 F.3d 1357,
1364 (Fed. Cir. 2017) (internal quotation marks omitted).
“Circumstantial evidence can support a finding of specific
intent to induce infringement.” Vanda Pharm. Inc. v. W.-
Ward Pharm. Int’l Ltd., 887 F.3d 1117, 1129 (Fed. Cir.
2018); Warsaw Orthopedic, Inc. v. NuVasive, Inc., 824
F.3d 1344, 1347 (Fed. Cir. 2016). “[I]nducement can be
found where there is [e]vidence of active steps taken to
encourage direct infringement, which can in turn be found
in advertising an infringing use or instructing how to
engage in an infringing use.” Vanda, 887 F.3d at 1129
(internal quotation marks omitted). Direct infringement
and inducement are issues of fact. Sanofi v. Watson
Labs., Inc., 875 F.3d 636, 645 (Fed. Cir. 2017); 01 Com-
munique Lab., Inc. v. LogMeIn, Inc., 687 F.3d 1292, 1296
(Fed. Cir. 2012).
                             1
    Substantial evidence supports the jury’s finding of
underlying direct infringement by surgeons. Dr. Barry
presented the results of a survey—the Neal Survey—that
asked spine surgeons questions about the spine derotation
38                                  BARRY v. MEDTRONIC, INC.

surgeries they had performed in the last two years. See
J.A. 5449–57. 12 In particular, the survey asked doctors
whether they had performed surgeries that included the
following steps:
     Insert 2 spinal rods through pedicle screws on
     multiple vertebrae (at any stage of the proce-
     dure)[.] Attach derotators to pedicle screws on 2
     or more vertebrae. Mechanically link 2 or more
     derotators. Link 2 or more different derotators at-
     tached to screws in a second group of 2 or more
     vertebrae (the 2 groups may have vertebrae in
     common). Both sets of linked derotators are
     moved simultaneously[.] Engage pedicle screw
     locking mechanism to hold vertebrae in derotated
     position[.]
J.A. 5454.
     Medtronic argues insufficiency, or even inadmissibil-
ity, of the Neal Survey because it did not specifically
name the accused Medtronic VCM kit in asking doctors
what they did. We do not think, however, that Medtronic
has shown error in the admission of or reliance on the
survey as reasonably indicating the amount of activity by
surgeons that would infringe.
    The steps recited in the survey’s inquiry track the
claim language in the patent. The patent claim language
includes: “implanting . . . each pedicle screw in a pedicle
region of each . . . first group of multiple vertebrae of a
spinal column,” ’358 patent, col. 6, lines 22–23; “a first
group of pedicle screw engagement members which are

     12 The parties have not specified precisely when the
Neal Survey was conducted. But the district court said
that it was not completed when Dr. Barry filed a motion
concerning non-VCM products, a motion filed in late
February 2016. J.A. 15168 n.8.
BARRY v. MEDTRONIC, INC.                                     39

mechanically linked with said first handle means” of the
“first pedicle screw cluster derotation tool, id., col. 6, lines
13–17; “in a single motion simultaneously rotating said
vertebrae of said first group of multiple vertebrae,” id.,
col. 6, lines 33–35; and “actuating said spinal rod en-
gagement means to secure said vertebrae in their respec-
tive and relative positions,” id., col. 6, lines 53–55. On the
record before us, we cannot say, as a matter of law, that a
survey like this one had to itemize every single claim
element: some claim elements might, for example, be
essentially universal accompaniments of the steps includ-
ed in the questions, making their inclusion pointlessly
complicating. To establish the inadequacy of the survey,
Medtronic had to show with specificity that the absence of
some inquiry made the questions asked and answers
given an unreliable indicator of the occurrence of activity
that constitutes direct infringement. It has not done so.
And if the identification of substantive steps in the survey
was adequate, the omission of the “VCM” name makes no
difference.
    The Neal Survey asked not only about specific steps
but also about surgeons’ use of Medtronic’s Horizon
System. J.A. 5451. According to Dr. Barry’s expert,
moreover, any use of the Horizon System to derotate a
spine would have used the VCM kit. The jury could
accept that testimony. Although Medtronic has argued
that use of certain tube derotators might not infringe yet
would have been captured by the Neal Survey about what
surgeons actually used, the jury could reject that conten-
tion. There was evidence indicating that such derotators
would not have worked as the claims require. Medtronic
has also argued, in this court and in its post-trial motion,
that the Neal Survey would have captured use of its
SmartLink product, which it says would be non-
infringing; but all evidence of SmartLink was excluded
from the trial, with Medronic’s agreement, so such evi-
40                                 BARRY v. MEDTRONIC, INC.

dence cannot support Medtronic’s challenge to the verdict.
Barry, 230 F. Supp. 3d at 642 n.9.
    The Neal Survey is not the only evidence of direct in-
fringement. The jury could find that Dr. Lenke himself
used the accused VCM kit. Dr. Lenke testified that when
he performed derotations, the technique involving the
VCM kit “would be the technique . . . that [he] would use”
and continued to use after 2010 (the year the ’358 patent
issued). J.A. 2706–08. He also continued to educate other
surgeons on this technique after 2010.
    Medtronic also makes an argument directed specifi-
cally to infringement of the ’121 patent. It points to the
requirement, stated in that patent’s claim 2 as quoted
above, of a cross-linking member connecting two handle
means, each of which links three screw engagement
members (for simultaneous manipulation). Medtronic
contends that there was insufficient evidence, from the
Neal Survey or otherwise, of surgeons’ using such a three-
by-three linking step with the VCM kit. We disagree.
The Neal Survey asked about surgeons’ using “6 or more
derotators linked by lateral and transverse connections
and moved simultaneously,” J.A. 5454, and Dr. Barry’s
expert testified that the three-by-three linking step would
be carried out by surgeons following the instructions on
the VCM kit’s lid. See Barry, 230 F. Supp. 3d at 644–45.
    In sum, the jury could properly find that there was di-
rect infringement of both patents at issue here, of a scope
indicated by the Neal Survey.
                            2
    Substantial evidence also supports the finding that
Medtronic induced infringement after issuance of Dr.
Barry’s two patents. On appeal, Medtronic focuses on the
timing of its inducing actions to contend otherwise, argu-
ing that there was insufficient proof of inducement after
the patents’ issuance. We reject the contention, agreeing
BARRY v. MEDTRONIC, INC.                               41

with the district court.   See Barry, 230 F. Supp. 3d at
245–46.
    VCM was on the market four years before the ’358 pa-
tent issued and seven years before the ’121 patent issued.
The Neal Survey asked whether surgeons “received any
information or training (formal or informal) regarding
derotation of multiple vertebrae using linked derotators
from that source,” without asking the dates of the infor-
mation received. J.A. 5455. There was extensive evi-
dence about the training materials provided by Medtronic
and its sales representatives. Importantly, every VCM kit
that went out had instructions on it, and the Medtronic
sales force was constantly teaching surgeons the nuances
of and techniques for using the devices. Dr. Lenke also
testified that he was still instructing surgeons on using
the VCM kit after 2010. On the evidence of record, we
conclude, the jury could permissibly find inducement in
the period after patenting.
                             F
    Medtronic challenges the jury’s damages award. But
the challenge is dependent on our accepting Medtronic’s
challenges to use of the Neal Survey to establish in-
fringement, which we have rejected. We add here only
that the district court carefully considered Medtronic’s
challenges to the methodology of the Neal Survey and
denied Medtronic’s motion to exclude the survey, conclud-
ing that Medtronic’s criticisms went to the weight of the
evidence, not its relevance and reliability. Barry, 230 F.
Supp. 3d at 641. We see no abuse of discretion in that
evidentiary ruling.
                            III
    For the foregoing reasons, we reject Medtronic’s chal-
lenges on appeal and affirm the judgment of the district
court.
   Costs to Dr. Barry.
42         BARRY v. MEDTRONIC, INC.

     AFFIRMED
  United States Court of Appeals
      for the Federal Circuit
                 ______________________

                   MARK A. BARRY,
                    Plaintiff-Appellee

                            v.

                  MEDTRONIC, INC.,
                  Defendant-Appellant
                 ______________________

                       2017-2463
                 ______________________

   Appeal from the United States District Court for the
Eastern District of Texas in No. 1:14-cv-00104-RC, Chief
Judge Ron Clark.
                 ______________________

PROST, Chief Judge, dissenting in part.
    I join the majority’s opinion regarding the ’121 patent.
I respectfully dissent, however, from its conclusion re-
garding the ’358 patent.
    The facts are simple. More than one year before filing
for the ’358 patent, Dr. Barry successfully performed his
claimed surgical method on three different patients,
charging each his normal fee. Dr. Barry’s method was
2                                   BARRY v. MEDTRONIC, INC.

thus prima facie “on sale” or in “public use” before the
critical date under 35 U.S.C. § 102(b). 1
     The majority concludes otherwise based on Dr. Bar-
ry’s litigation testimony. Dr. Barry testified that, even
though he charged his patients and successfully per-
formed the claimed method three times before the critical
date, he was not truly satisfied with his method until a
follow-up after the third surgery—a follow-up that oc-
curred just after the critical date. Never mind that Dr.
Barry appreciated that his method worked as of a sur-
gery’s completion. And never mind that successful follow-
ups for the first two surgeries occurred before the critical
date. Dr. Barry testified that he needed that third follow-
up to be satisfied. On this basis, the majority concludes
Medtronic failed to show that the asserted claims of the
’358 patent are invalid under § 102(b)’s statutory bars.
    Both the Supreme Court’s and our precedent require
invalidating the asserted claims under § 102(b) as a
matter of law on this record. For this reason, I dissent.
                              I
                              A
    Whether an invalidating sale or public use has oc-
curred is a question of law reviewed de novo, based on
underlying facts reviewed for substantial evidence follow-
ing a jury verdict. Leader Techs., Inc. v. Facebook, Inc.,
678 F.3d 1300, 1305 (Fed. Cir. 2012).
    The § 102(b) on-sale bar applies when, before the crit-
ical date, the claimed invention was (1) the subject of a
commercial offer for sale; and (2) ready for patenting.

    1  All citations to sections of Title 35 are to their pre-
AIA version.
BARRY v. MEDTRONIC, INC.                                    3

Pfaff v. Wells Elecs., Inc., 525 U.S. 55, 67 (1998). 2 Med-
tronic needed to prove the facts underlying these two
conditions by clear and convincing evidence. See, e.g.,
Allen Eng’g Corp. v. Bartell Indus., Inc., 299 F.3d 1336,
1352 (Fed. Cir. 2002).
    This case mostly concerns Pfaff’s ready-for-patenting
prong. This prong may be satisfied “in at least two ways”:
by proof of reduction to practice before the critical date; or
by proof that before the critical date the inventor had
prepared enabling drawings or other descriptions. 525
U.S. at 67–68. And to establish a reduction to practice,
we have held that a patent challenger must show that the
inventor “(1) constructed an embodiment or performed a
process that met all the [claim] limitations and (2) deter-
mined that the invention would work for its intended
purpose.” In re Omeprazole Patent Litig., 536 F.3d 1361,
1373 (Fed. Cir. 2008) (internal quotation marks omitted)
(quoting z4 Techs., Inc. v. Microsoft Corp., 507 F.3d 1340,
1352 (Fed. Cir. 2007)).

    2   I focus the rest of my discussion on § 102(b)’s on-
sale bar as opposed to its public-use bar, though my
ultimate conclusion is the same for each. The public-use
bar applies when, before the critical date, the claimed
invention was (1) in public use; and (2) ready for patent-
ing. Invitrogen Corp. v. Biocrest Mfg., L.P., 424 F.3d
1374, 1379 (Fed. Cir. 2005). The ready-for-patenting
prong is the same for both bars, and the public-use prong
is met if the purported use was accessible to the public or
commercially exploited. Id. at 1379–80. The claimed
inventions were commercially exploited for essentially the
same reasons that they were the subject of a commercial
sale or offer for sale. I see no material difference between
the two bars in this case or in the way that evidence of
experimental use would affect their application.
4                                  BARRY v. MEDTRONIC, INC.

     Even if a patent challenger makes out a prima facie
case of the on-sale bar, a patentee may negate the bar’s
application with evidence that the sale was primarily for
experimental purposes. See Electromotive Div. of Gen.
Motors Corp. v. Transp. Sys. Div. of Gen. Elec. Co., 417
F.3d 1203, 1210 (Fed. Cir. 2005) (proceeding in a “step-
wise fashion,” analyzing first whether there were any pre-
critical-date sales and then whether any such sales were
negated by experimentation); Netscape Commc’ns Corp. v.
Konrad, 295 F.3d 1315, 1321 (Fed. Cir. 2002) (“To estab-
lish that an otherwise public use does not run afoul of
[§] 102(b), it must be shown that the activity was substan-
tially for purposes of experiment.” (internal quotation
marks omitted)); TP Labs., Inc. v. Prof’l Positioners, Inc.,
724 F.2d 965, 971–72 (Fed. Cir. 1984).
                             B
     The majority provides two bases for its conclusion
that the asserted claims are not invalid under § 102(b)
and Pfaff. Majority Op. 11–12. First, it says that the
claimed methods were not ready for patenting before the
critical date because they did not satisfy this court’s
reduction-to-practice test before that date. Majority Op.
13–18. Second, it says that the three pre-critical-date
surgeries were for experimental purposes, thus negating
application of a § 102(b) bar. Majority Op. 24–31.
    Part II below concerns how Medtronic met Pfaff’s two-
prong test. Specifically, Part II.A shows that Pfaff’s
commercial-sale prong was satisfied. Part II.B shows that
Pfaff’s ready-for-patenting prong was satisfied because
our reduction-to-practice test was satisfied. Part II.C
shows that, regardless of whether the claimed methods
were “reduced to practice,” they were ready for patenting.
    Part III concerns how the majority misapplies our re-
duction-to-practice test. This part also addresses a con-
fusing aspect of our case law that the majority’s opinion
BARRY v. MEDTRONIC, INC.                                     5

perpetuates.    Part IV concerns the experimental-use
doctrine.
                              II
    The key facts are undisputed. The ’358 patent’s criti-
cal date is December 30, 2003. Dr. Barry performed three
pre-critical-date surgeries that practiced all the limita-
tions of the asserted ’358 patent claims. These surgeries
occurred on August 4, 2003; August 5, 2003; and October
14, 2003. Dr. Barry charged his normal fee for them.
                              A
    The foregoing evidence establishes Pfaff’s commercial-
sale prong for each of the three pre-critical-date surgeries.
See Plumtree Software, Inc. v. Datamize, LLC, 473 F.3d
1152, 1163 (Fed. Cir. 2006) (“[P]erforming the patented
method for commercial purposes before the critical date
constitutes a sale under § 102(b).”); In re Kollar, 286 F.3d
1326, 1333 (Fed. Cir. 2002) (“[P]erforming the process
itself for consideration would . . . trigger the application of
§ 102(b).”). Therefore, absent sufficient evidence that
these surgeries were done for primarily experimental
purposes, they would satisfy the first Pfaff prong as a
matter of law.
                              B
    Medtronic also established that the inventions were
reduced to practice no later than the second surgery’s
completion, and therefore were ready for patenting by
then. Pfaff, 525 U.S. at 67–68 (identifying reduction to
practice as a basis for establishing the ready-for-patenting
prong).
    Reduction to practice is a question of law we review de
novo. DSL Dynamic Scis. Ltd. v. Union Switch & Signal,
Inc., 928 F.2d 1122, 1125 (Fed. Cir. 1991). To establish a
reduction to practice, we have held that a patent chal-
lenger must show that the inventor (1) constructed an
6                                  BARRY v. MEDTRONIC, INC.

embodiment or performed a process that met all the claim
limitations and (2) determined that the invention would
work for its intended purpose. In re Omeprazole, 536 F.3d
at 1373. It is undisputed that each of the three pre-
critical-date surgeries met all the claim limitations. The
only question is when Dr. Barry determined that his
methods worked for their intended purpose.
    The claims state the inventions’ intended purpose:
“the amelioration of aberrant spinal column deviation
conditions.” ’358 patent col. 6 ll. 7–8. Dr. Barry testified
that such amelioration happened during surgery:
    Q. And there is a term that is used in the patent
    that is not a term that is familiar to me as a lay-
    person, but it’s “amelioration.” Does that mean
    correction?
    A. Yes.
    Q. Okay. So, it happens right there in the operat-
    ing room, on the spot, true?
    A. The surgical correction of the rotated vertebrae
    back to the midline, yeah, happens with that ma-
    neuver. Yes.
J.A. 1369–70. Dr. Barry’s expert testified similarly.
J.A. 1960 (“Q. And at least for the vertebrae, that dero-
tation problem, you’ll know if there was at least some
amelioration when the surgery is over. A. Fair enough.”)
    Once this amelioration happened, Dr. Barry secured
the derotated vertebrae in place with rods and screws, as
the claims require:
    Q. And can you explain for the jury, please, what
    happens once you get the vertebrae derotated into
    the proper alignment? How do you hold it there?
    A. Well, as mentioned, you have screws up and
    down throughout that area of that curve. Once
BARRY v. MEDTRONIC, INC.                                     7

    those vertebrae are rotated back into the midline
    and you have the correction that you are happy
    with, you are comfortable with, you lock down the
    screws to the two rods. . . . So, that’s at the end of
    the procedure where all of the implants—screws,
    rods, and the setscrews—are all tightened down,
    locked down.
J.A. 1158–59 (emphasis added); see ’358 patent col. 6
ll. 52–56.
    Thus, by no later than the second surgery’s comple-
tion, Dr. Barry appreciated that his invention worked for
its intended purpose—to ameliorate aberrant spinal
column deviation conditions. 3 His inventions were re-
duced to practice by then as a matter of law.
                              C
    Though sufficient, reduction to practice is not neces-
sary for § 102(b)’s on-sale bar to apply. Pfaff, 525 U.S. at
66 (concluding that it is unnecessary “to engraft a reduc-
tion to practice element into the meaning of the term
‘invention’ as used in § 102(b)”). Rather, the standard is
whether the invention was “ready for patenting”—that is,
whether the inventor “could have obtained a patent.” Id.
at 67–68; see id. at 62–63.

   3     Because the claims’ preamble refers to the amelio-
ration of “aberrant spinal column deviation conditions”
(plural), and because Dr. Barry testified that his patients
had different types of conditions, I place the time of
reduction to practice at the completion of the second
surgery—not the first. Given that both of the first two
surgeries (and their respective follow-ups) occurred before
the critical date, the difference is immaterial here.
8                                  BARRY v. MEDTRONIC, INC.

     The record demonstrates that, regardless of when his
inventions were reduced to practice, Dr. Barry could have
obtained a patent before the critical date. By August 5,
2003, he had already performed the claimed methods on
what he contends were two different types of aberrant
spinal column deviation conditions. There was at least
some amelioration of those conditions by the end of the
surgeries. At this point, Dr. Barry could have satisfied
the enablement and written-description requirements of
§ 112 and credibly claimed utility under § 101. See Alcon
Research Ltd. v. Barr Labs., Inc., 745 F.3d 1180, 1189–90
(Fed. Cir. 2014) (noting that “a patent does not need to
guarantee that the invention works for a claim to be
enabled” and that “[t]here is no requirement that the
disclosure contain either examples or an actual reduction
to practice” (internal quotation marks omitted)); CFMT,
Inc. v. Yieldup Int’l Corp., 349 F.3d 1333, 1339 (Fed. Cir.
2003) (describing the relationship between enablement
and utility and concluding that, “[b]ecause the preamble
term ‘cleaning’ means only ‘removal of contaminants,’ not
removal of all contaminants or removal of contaminants
according to [a] commercial standard, the inventor shows
utility and enables the invention by disclosing ‘removal of
contaminants’”).
     By focusing only on reduction to practice, the majority
misses Pfaff’s point—readiness for patenting is broader
than reduction to practice and is meant to answer wheth-
er the inventor could have obtained a patent on his or her
invention. This court captured a similar insight even
before Pfaff. We noted that “the thrust of the on-sale
inquiry is whether the inventor thought he had a product
which could be and was offered to customers, not whether
he could prevail under the technicalities of reduction to
practice appropriate to determining priority of invention
under interference law.” Paragon Podiatry Lab., Inc. v.
KLM Labs., Inc., 984 F.2d 1182, 1187 n.5 (Fed. Cir. 1993);
cf. Pfaff, 525 U.S. at 60–61 (observing that neither § 100
BARRY v. MEDTRONIC, INC.                                    9

nor § 101 mentions “reduction to practice” and that the
statute’s only specific reference to that term is in § 102(g),
which concerns resolving priority disputes between two
competing claimants to a patent).
    The same insights apply here. Regardless of whether
Dr. Barry satisfied our reduction-to-practice test as of the
second surgery’s completion, his inventions were ready for
patenting by then.
                             III
     The majority disagrees that Dr. Barry’s inventions
were ready for patenting before the critical date. The
concept of an “intended purpose” is central to the majori-
ty’s analysis and conclusion.
    First, the majority reasons that Dr. Barry’s claimed
methods were not ready for patenting until they were
reduced to practice, and that they were not reduced to
practice until Dr. Barry knew that they would work for
their intended purpose. The majority accepts that Dr.
Barry needed the third follow-up to determine that the
inventions worked for their intended purpose. Majority
Op. 13; see id. at 14–19. This is error, because the majori-
ty asks more of the “intended purpose” than what the
claims and specification define it to be.
    Second, the majority finds support in cases where we
have discussed “intended purpose” in the context of the
experimental-use doctrine. But that doctrine contem-
plates a broader conception of “intended purpose” than
what is required to show reduction to practice. State-
ments in our case law that loosely refer to an “intended
purpose” are, regrettably, confusing. But the majority
perpetuates the confusion in reaching its result. And its
approach threatens to render superfluous a substantial
body of law starting with the Supreme Court’s seminal
City of Elizabeth case.
    I discuss these two problems in turn.
10                                 BARRY v. MEDTRONIC, INC.

                             A
    To know whether and when the inventor determined
that the invention would work for its intended purpose for
reduction to practice, we must first know what the “in-
tended purpose” is. Although the testing necessary to
determine whether an invention would work for its in-
tended purpose is a factual question, z4 Techs., 507 F.3d
at 1352, defining the intended purpose is a legal question
based on the claims and specification, see Manning v.
Paradis, 296 F.3d 1098, 1102–04 (Fed. Cir. 2002).
    Here, the claims define the intended purpose as “the
amelioration of aberrant spinal column deviation condi-
tions.” ’358 patent col. 6 ll. 7–8. As both Dr. Barry and
his expert testified, that amelioration is apparent and
appreciated during a surgery when the surgeon rotates
and straightens the vertebrae and then locks them into
place. See supra Part II.B. That testimony, along with
the undisputed fact that the pre-critical-date surgeries
met all the claim limitations, should end the reduction-to-
practice inquiry.
    To conclude otherwise, the majority must conceive of a
more exacting intended purpose—one that, based on Dr.
Barry’s testimony, includes clearing a follow-up at a
certain time and working across three different types of
conditions (not just two). In doing so, the majority legally
errs by looking beyond the claims and the specification to
effectively define the “intended purpose” for reduction to
practice. 4 Conner v. Joris, 241 F.2d 944, 947 (CCPA 1957)

     4  The majority also references Dr. Barry’s expert’s
testimony as supporting Dr. Barry. Majority Op. 16–17.
But much of that testimony concerns what the expert
thought Dr. Barry was thinking, J.A. 2899, which adds
very little to an objective, patent-based assessment of
BARRY v. MEDTRONIC, INC.                                  11

(“In going beyond both the [claim] and the specification to
glean [an inventor’s] intended purpose the [B]oard has
gone far beyond any position supported by the cases cited
or any that we have been able to find.”); see Land v.
Regan, 342 F.2d 92, 98–99 (CCPA 1965) (criticizing going
beyond the claims and specification to glean an inven-
tion’s intended purpose); cf. z4 Techs., 507 F.3d at 1352
(finding error in the district court’s definition of intended
purpose as “stop[ping] piracy” because the claim language
indicated a purpose only of reducing piracy).
    To be sure, the majority suggests that the ’358 patent
describes follow-up time and the three-surgery require-
ment as part of the inventions’ intended purpose. See
Majority Op. 18–19 (referencing a “common-sense ap-
proach to identifying the intended purpose [that] is rooted
in the preamble claim language as well as the specifica-
tion”). I am unpersuaded.
    The claims say nothing about follow-up time. They
say, “the amelioration of aberrant spinal column deviation
conditions.” ’358 patent col. 6 ll. 7–8. The district court
concluded that “amelioration” would be accorded its
customary meaning, which a person of ordinary skill in
the art would understand as “to improve.” J.A. 33–34.
Both Dr. Barry and his expert testified that the aberrant
spinal column deviation conditions were ameliorated, or

what the inventions’ intended purpose is. And, insofar as
the majority relies on standards for peer-reviewed publi-
cations as they relate to follow-up time, Majority Op. 17, I
am not convinced that those standards are, or should be,
relevant to reduction to practice or readiness for patent-
ing under the U.S. patent laws. For instance, Dr. Barry’s
expert testified that such publications require two years’
follow-up time, J.A. 2900, but Dr. Barry successfully filed
for a patent well before that.
12                                 BARRY v. MEDTRONIC, INC.

improved, as of a surgery’s completion. And Dr. Barry
testified that he appreciated as much at the time. Supra
Part II.B.
    The specification also says nothing relating follow-up
time to the inventions’ intended purpose. The majority
references two portions of the specification in its discus-
sion, but neither supports its position. First, it cites the
background section. Majority Op. 18–19 (citing ’358
patent cols. 1–2). This section discusses prior-art treat-
ment regimens and problems from untreated scoliosis; it
says nothing about follow-up criteria as it relates to the
intended purpose of Dr. Barry’s inventions. Second, the
majority refers to the four “objects of the invention”
articulated in the summary of the invention. Majority
Op. 18 (citing ’358 patent col. 3 ll. 10–34). Again, these
objectives say nothing about follow-up time. Quite the
contrary; they describe what happens in the operating
room—for example, (1) “facilitat[ing] the application of
significant derotational forces to individual vertebra, with
substantially reduced risk for fracture thereof upon
application of such forces,” ’358 patent col. 3 ll. 23–25
(emphasis added); and (2) “facilitat[ing] the application of
forces to vertebrae of affected spinal column segments en
bloc, thereby distributing otherwise potentially injurious
forces in a manner for safely achieving over-all spinal
column correction or derotation,” id. at col. 3 ll. 30–33
(emphasis added).
     Nor does the intended purpose contemplate working
across three different types of curvatures, as opposed to
just two. The claims’ body requires amelioration of “an
aberrant spinal column deviation condition,” ’358 patent
col. 6 ll. 35–36 (emphasis added), and the preamble men-
tions only “amelioration of aberrant spinal column devia-
tion conditions,” id. at col. 6 ll. 7–8. The majority
identifies nothing in the patent itself—whether in the
claims or specification—that explains how working across
three, not just two, curvatures is part of the inventions’
BARRY v. MEDTRONIC, INC.                                   13

intended purpose. Therefore, even if I were to accept that
the ’358 patent’s language made follow-up time relevant
to the inventions’ intended purpose, I would still fail to
understand the legal relevance of Dr. Barry’s alleged need
for the third surgery’s follow-up, as opposed to just the
first two, to determine whether his invention worked for
its intended purpose (so as to establish reduction to
practice).
    The majority suggests that Medtronic “has not mean-
ingfully presented, let alone supported” the argument
that follow-ups on two surgeries (covering two conditions)
were enough to establish reduction to practice. Majority
Op. 19 n.7. I disagree. The majority acknowledges that
Medtronic’s opening brief argued that the two follow-ups
from the August surgeries were enough. Id. Dr. Barry
responded that he needed to test his invention on “differ-
ent anatomies” and that it was only after the third follow-
up that he knew whether he had successfully treated the
“three most common[] curve types.” Dr. Barry’s Resp. Br.
25–26 (alteration in original). Medtronic replied:
    [A]n invention works for its intended purpose as
    long as there is some demonstration of the worka-
    bility or utility of the claimed invention. A
    demonstration of its use in two patients certainly
    qualifies. After all, the claims are not confined to
    methods that ameliorate every patient’s spinal
    deviation condition.
Medtronic’s Reply Br. 8 (citation and internal quotation
marks omitted); see id. at 8–9 (citing Dr. Barry’s testimo-
ny regarding the surgeries, their follow-ups, and the
patients’ curve types). This straightforward argument is
before us. Not even Dr. Barry has urged otherwise.
    If Dr. Barry wanted to claim or describe his inven-
tions’ intended purpose differently—for example, with
reference to satisfying a standard of care that contem-
plates a certain amount of follow-up time, or versatility
14                                 BARRY v. MEDTRONIC, INC.

across more than two curvature types—he could have
done so. But his claims and specification say nothing of
the sort. Given his testimony that before the critical date
he practiced his invention (as he later claimed it) and
achieved its purpose (as he later described it), his inven-
tion was reduced to practice before then as a matter of
law.
                             B
    To find Dr. Barry’s inventions not ready for patenting,
the majority analogizes to several cases it says support its
view of the inventions’ intended purpose. Majority Op.
20–22. Its analysis of Pfaff’s ready-for-patenting prong
reflects some confusion in our case law regarding the
relationship among reduction to practice, an invention’s
intended purpose, and the experimental-use doctrine.
    Again, reduction to practice requires proof that the
inventor determined that the invention would work for its
intended purpose. In re Omeprazole, 536 F.3d at 1373.
Therefore, showing readiness for patenting (at least, via
reduction to practice) requires proof that the inventor
determined that the invention would work for its intended
purpose. Yet we have also said that a use may be experi-
mental if it is to “determine whether an invention will
work for its intended purpose.” Polara Eng’g Inc. v.
Campbell Co., 894 F.3d 1339, 1348 (Fed. Cir. 2018) (quot-
ing Clock Spring, L.P. v. Wrapmaster, Inc., 560 F.3d 1317,
1327 (Fed. Cir. 2009)). But if that determination has not
already been made, then the invention would not be ready
for patenting in the first place. Therefore, any considera-
tion of whether a use was experimental would be super-
fluous, as there would be no prima facie case of a § 102(b)
bar to begin with. This is how the majority resolves the
case. See Majority Op. 23.
   I am skeptical, however, of an approach that would
render the experimental-use doctrine superfluous based
upon the same considerations of an “intended purpose”
BARRY v. MEDTRONIC, INC.                                  15

being considered elsewhere. 5 Instead of rendering this
doctrine superfluous, the better and more accurate view is
that the considerations of an “intended purpose” are not
really the same as between reduction to practice and
experimental use.
     The experimental-use doctrine exists to afford an in-
ventor the ability to experiment with his or her invention
via what would otherwise constitute a barring sale or
public use. The focus is on the inventor’s intent in mak-
ing the sale or using the invention publicly; if it is for
primarily experimental purposes, we do not consider the
sale or use barring. See Electromotive Div., 417 F.3d at
1211. Several factors have emerged to evaluate that
intent—e.g., the amount of control the inventor main-
tained, whether there was a secrecy obligation, the degree
of commercial exploitation, and whether customers were
aware the inventor was experimenting. Id. at 1212–14.
Such factors are unrelated to how far along the invention
is in terms of reduction to practice. Rather, they bear on
the inventor’s intent.
    Given these differences, a subjective, expansive un-
derstanding of an invention’s “intended purpose”—one
that accommodates the good-faith, perfectionist inven-
tor—is considered as part of the experimental-use inquiry.
This is the way the Supreme Court addressed the issue in
the City of Elizabeth pavement case:
    Durability was one of the qualities to be attained.
    [The inventor] wanted to know whether his
    pavement would stand, and whether it would re-
    sist decay. Its character for durability could not

    5    I am all the more skeptical given that Pfaff explic-
itly reaffirmed the continued vitality of the experimental-
use doctrine. 525 U.S. at 64–65, 67.
16                                  BARRY v. MEDTRONIC, INC.

     be ascertained without its being subjected to use
     for a considerable time. He subjected it to such
     use, in good faith, for the simple purpose of ascer-
     taining whether it was what he claimed it to be.
City of Elizabeth v. Am. Nicholson Pavement Co., 97 U.S.
126, 136 (1877); id. at 137 (justifying, on policy grounds,
delaying filing for a patent when the delay is “occasioned
by a bona fide effort to bring [the] invention to perfection,
or to ascertain whether it will answer the purpose intend-
ed”).
    In fact, most of the cases the majority analogizes to in
its not-ready-for-patenting discussion actually analyze
this subjective, outside-the-patent-language “intended
purpose” as part of experimental use. Majority Op. 20–
22; see Polara, 894 F.3d at 1349 (“The jury could have
properly based its finding of experimental use on the need
for testing to ensure the durability and safety of the
claimed [invention].”); Manville Sales Corp. v. Paramount
Sys., Inc., 917 F.2d 544, 550 (Fed. Cir. 1990) (“Because
[the inventor] . . . did not offer to sell the [invention] to
anyone else until after it was tested in the cold, rain,
snow, and wind—an environment in which it was de-
signed to operate—we must agree with the district court
that experimentation, and not profit, was the primary
motive behind [the use].”); TP Labs., 724 F.2d at 972.
    Thus, if an inventor’s pre-critical-date sale or public
use is to test an unclaimed or undescribed, yet inherent,
feature of an invention (e.g., durability, safety), such
testing may support the inventor’s overall claim of exper-
imental use and thereby avoid invalidity. See Electromo-
tive Div., 417 F.3d at 1211–12. But neither this testing
nor the inventor’s assertions regarding his or her subjec-
tive desire for such testing should control the ready-for-
patenting inquiry. Pfaff’s “ready for patenting” does not
mean whenever the inventor was ready to file for a pa-
tent.
BARRY v. MEDTRONIC, INC.                                   17

                            IV
    Given my conclusion that Medtronic made a prima fa-
cie showing of both Pfaff prongs, I must address whether
Dr. Barry presented enough evidence that he conducted
the three surgeries with experimental purpose sufficient
to negate an on-sale bar. Although the majority does not
address the parties’ respective burdens in this context, I
address them briefly. I then address the evidence.
                            A
   The Supreme Court addressed the burdens issue in
Smith & Griggs Manufacturing Co. v. Sprague:
   In considering the evidence as to the alleged prior
   use for more than two years of an invention,
   which, if established, will have the effect of inval-
   idating the patent, and where the defense is met
   only by the allegation that the use was not a pub-
   lic use in the sense of the statute, because it was
   for the purpose of perfecting an incomplete inven-
   tion by tests and experiments, the proof, on the
   part of the patentee, the period covered by the use
   having been clearly established, should be full,
   unequivocal, and convincing.
123 U.S. 249, 264 (1887) (emphasis added). The Court
reiterated the rule in Root v. Third Avenue Railroad Co.,
146 U.S. 210, 226 (1892).
    Over forty years later, the Second Circuit interpreted
and applied this language. With Judge Learned Hand
writing, the court concluded that, on the issue of experi-
mental purpose, “the patentee has the burden, once the
[prior] use is proved, and he must establish it by stronger
proof than in ordinary civil suits.” Aerovox Corp. v.
Polymet Mfg. Corp., 67 F.2d 860, 861 (2d Cir. 1933)
(Hand, J.). The court noted that the First, Third, and
Seventh Circuits all read Smith & Griggs the same way.
Id. (collecting cases). Indeed, the court “should have
18                                BARRY v. MEDTRONIC, INC.

supposed this settled” but for contrary language in a
Sixth Circuit case, Austin Machinery Co. v. Buckeye
Traction Ditcher Co., which said that “the legal and heavy
burden of proof as to all the elements involved continues
until the end upon one who attacks the patent grant.” 13
F.2d 697, 700 (6th Cir. 1926). Although Judge Hand saw
merit in both positions, he concluded that the majority
view was authoritative “until the Supreme Court decides
otherwise.” Aerovox, 67 F.2d at 861. The Supreme Court
has not decided otherwise.
    This court has, though. In TP Laboratories, Inc. v.
Professional Positioners, Inc., the court addressed the
burdens applicable to a patent challenger’s § 102(b)
defense and a patentee’s corresponding assertion of exper-
imental use. It followed Austin and held that “the burden
of proof [is] upon the party attacking the validity of the
patent, and that burden of persuasion does not shift at
any time to the patent owner.” 724 F.2d at 971; id. at 971
n.3 (citing Austin, 13 F.2d at 700). Although the court
acknowledged Smith & Griggs in a footnote, it saw no
conflict there. 724 F.2d at 971 & n.3.
    The TP Laboratories court further opined that, even if
Smith & Griggs expressed a contrary view—i.e., one that
“impose[d] the ultimate burden of persuasion on the
patent holder rather than merely the burden of going
forward with countering evidence”—the Supreme Court’s
view would not be “tenable” in light of the subsequently
enacted statutory presumption of validity in 35 U.S.C.
§ 282. 724 F.2d at 971 n.3. This reasoning was question-
able even at the time. As several commentators noted,
the presumption of validity long predated the 1952 Patent
Act. 6 The court’s reasoning has not improved with age.

     E.g., William C. Rooklidge & Stephen C. Jensen,
     6

Common Sense, Simplicity and Experimental Use Nega-
BARRY v. MEDTRONIC, INC.                                 19

See Microsoft Corp. v. i4i Ltd. P’ship, 564 U.S. 91, 102
(2011) (“[B]y the time Congress enacted § 282 and de-
clared that a patent is ‘presumed valid,’ the presumption
of patent validity had long been a fixture of the common
law.” (citing Radio Corp. of Am. v. Radio Eng’g Labs.,
Inc., 293 U.S. 1 (1934))).
     Thus, in TP Laboratories, the patentee’s burden of
persuasion on experimental use became a burden of
production: “[I]f a prima facie case is made of public use,
the patent owner must be able to point to or must come
forward with convincing evidence to counter that show-
ing.” 724 F.2d at 971 (emphasis added). And while TP
Laboratories at least required a patentee to come forward
with “convincing” evidence of experimental use, we later
held that this does not imply a heightened standard, such
as one akin to “clear and convincing.” Lisle Corp. v. A.J.
Mfg. Co., 398 F.3d 1306, 1316 (Fed. Cir. 2005). But cf. In
re Dybel, 524 F.2d 1393, 1401 (CCPA 1975) (holding that,
in light of a prima facie case of an on-sale bar, the appli-
cant “had the burden of establishing by clear and convinc-
ing evidence that such sales were for experimental
purposes”).
                             B
    Even under the burden-of-production approach set
forth in TP Laboratories, I conclude that Dr. Barry’s

tion of the Public Use and On Sale Bars to Patentability,
29 J. Marshall L. Rev. 1, 44–45 (1995) (cited favorably in
Pfaff, albeit for a different proposition); see also 2A Chi-
sum on Patents § 6.02[8], p. 6-292 n.41 (2017) (noting that
“[t]he court’s basis for this holding is questionable” given
that “[t]he enactment of [§] 282 on the presumption of
validity in 1952 was generally thought to have codified
prior law”).
20                                 BARRY v. MEDTRONIC, INC.

evidence of experimental purpose was insufficient as a
matter of law to negate a bar.
     Most of Dr. Barry’s evidence of experimental purpose
as to the three pre-critical-date surgeries is just his own
after-the-fact testimony. See Majority Op. 26–27 (refer-
encing Dr. Barry’s testimony). 7 “[C]ertain things are
settled. Significantly, an inventor’s subjective intent to
experiment cannot establish that his activities are, in
fact, experimental.” Electromotive Div., 417 F.3d at 1212.
Indeed, we have repeatedly noted the minimal eviden-
tiary value of an inventor’s after-the-fact, litigation-
inspired testimony as to experimental intent. E.g., La-
Bounty Mfg., Inc. v. ITC, 958 F.2d 1066, 1071 (Fed. Cir.
1992) (“An inventor’s protestation of an intent to experi-
ment, expressed for the first time during litigation, is of
little evidentiary value, at best.”); see also Sinskey v.
Pharmacia Ophthalmics, Inc., 982 F.2d 494, 499 (Fed.
Cir. 1992) (“[A]fter-the-fact testimony of an inventor’s
subjective ‘experimental intent’ is entitled to minimal

     7  The majority suggests that other people were
aware that Dr. Barry was experimenting, Majority Op.
27–28, but its record citations do not withstand scrutiny.
Dr. Barry’s doctor colleague testified that she understood
him to be working on a technique sometime “in the 2002–
2004 time frame.” J.A. 1733. This testimony is vague
and says nothing about these particular surgeries, much
less their experimental purpose. Dr. Barry’s nurse col-
league said that it was “exciting when [the] team uses
[the] levers to correct the curve,” but said nothing about
whether she understood the procedure to be experimental.
J.A. 1370. And testimony concerning the DePuy medical-
device representative relates only to the development of
surgical tools, not these particular surgeries or whether
they were experimental. J.A. 1178–79.
BARRY v. MEDTRONIC, INC.                                21

weight.”), abrogated on other grounds by Pfaff, 525 U.S.
55 (1998); TP Labs., 724 F.2d at 972 (similar).
    Rather, we generally look to objective evidence to de-
termine whether a sale was for experimentation. Elec-
tromotive Div., 417 F.3d at 1212–13 (listing various
objective indicia); see Lough v. Brunswick Corp., 86 F.3d
1113, 1121 (Fed. Cir. 1996); In re Smith, 714 F.2d 1127,
1135 (Fed. Cir. 1983). The record is thin on objective
evidence indicating such a purpose.
    To begin, Dr. Barry kept no records reflecting any ex-
perimental intent as to these surgeries. We have ob-
served that the absence of such records weighs against a
finding of experimental use. See Lough, 86 F.3d at 1121
(finding the lack of recordkeeping important even with an
inventor less sophisticated than Dr. Barry); see also Clock
Spring, 560 F.3d at 1328; Netscape, 295 F.3d at 1322.
    Dr. Barry also charged his normal fee for the surger-
ies. The majority concludes that this fact points toward a
conclusion of experimental use. Majority Op. 27–28. Yet
I cannot see how charging one’s normal fee makes the sale
look like anything other than a normal sale. See Electro-
motive Div., 417 F.3d at 1217; Sinskey, 982 F.2d at 499.
Had Dr. Barry charged a premium, a claim of experi-
mental purpose would be difficult to maintain. Had he
charged less, it might suggest experimental purpose—or
it might not. Compare EZ Dock, Inc. v. Schafer Sys., Inc.,
276 F.3d 1347, 1352 (Fed. Cir. 2002) (citing, in support of
a conclusion of experimental use, fact that customer did
not pay full market price for the product and received free
equipment and free installation), with Petrolite Corp. v.
Baker Hughes Inc., 96 F.3d 1423, 1428 (Fed. Cir. 1996)
(finding evidence of a discount not determinative because
a patentee “may have created an on-sale bar despite
losing money on a sale” (citation omitted)). Either way, I
disagree with the majority’s conclusion that charging the
normal fee permits an inference of experimental use.
22                                 BARRY v. MEDTRONIC, INC.

Majority Op. 27–28. At best, this fact is neutral for Dr.
Barry. But the more natural inference is one of a sale for
commercial purposes.
     The majority places weight on the fact that Dr. Barry
maintained control over his method, but I find it hard to
do the same. Control can be a useful objective indicator of
experimental intent when it serves to distinguish between
a commercial sale and one that is experimental. For
example, if an inventor sells his or her inventive product
but retains some control over its use, that scenario looks
different from a normal sale—thus, more likely experi-
mental. Similarly, if an inventor sells his or her product
but forgoes an opportunity to retain some control, that
scenario looks more like a normal sale. In this case,
however, the nature of the inventor (a practicing surgeon)
and his invention (a surgical method) means the inventor
was likely going to retain sole control over the method for
as long as he was practicing it. Although Dr. Barry’s
control over his method is consistent with experimental
intent, given these circumstances, I cannot place much
weight on this consideration.
     Dr. Barry also did not inform his patients that he was
performing his surgical method for experimental purpos-
es. The majority dedicates considerable discussion to
minimizing the importance of this fact. It carefully parses
a statement in one of our prior cases, LaBounty, and finds
that informing a customer of experimental intent is only
relevant or necessary if at least two premises exist:
(1) the absence of other objective evidence of experimenta-
tion; and (2) the placement of the invention outside of the
inventor’s control. Majority Op. 29–30. Respectfully, I
believe the majority’s two-necessary-premises require-
ment over-reads LaBounty and overcomplicates what
should be a simple observation: if an inventor tells his or
her customer that the invention is for experimental
purposes, it is more likely that the inventor’s intent was
experimental; if he or she does not, it is less likely. Re-
BARRY v. MEDTRONIC, INC.                                  23

gardless, even if I were to accept that informing custom-
ers of experimental intent is more important when control
is lost, that would not mean it is irrelevant when control
is maintained. It remains useful as an objective indicator
of the inventor’s contemporaneous intent.
    In Dr. Barry’s case, all of the foregoing considera-
tions—the lack of records indicating experimentation, the
normal fee charged, the control exercised, and the failure
to inform customers of experimental purpose—would look
the same if the surgeries were for commercial purposes.
The only thing that affirmatively suggests these surgeries
were experimental is that Dr. Barry said they were—after
the fact, during litigation. As a matter of law, that is
insufficient to show experimental purpose.
                     *       *        *
    The record in this case shows that Dr. Barry waited
too long to file for the ’358 patent and that the on-sale bar
applies. I respectfully dissent from the majority’s contra-
ry conclusion.