RECOMMENDED FOR FULL-TEXT PUBLICATION
                                    Pursuant to Sixth Circuit I.O.P. 32.1(b)
                                             File Name: 14a0193p.06

                        UNITED STATES COURT OF APPEALS
                                         FOR THE SIXTH CIRCUIT
                                           _________________


 CHAROLETTE PAYNE; BRENT PAYNE,                   ┐
                           Plaintiffs-Appellants, │
                                                  │
                                                  │                          No. 13-6266
      v.                                          │
                                                                    >
                                                                   │
 NOVARTIS PHARMACEUTICALS CORPORATION,                             │
                           Defendant-Appellee.                     │
                                                                   ┘
                             Appeal from the United States District Court
                         for the Eastern District of Tennessee of Chattanooga
                      No. 1:12-cv-00077—Curtis L. Collier, Chief District Judge.
                                           Argued: August 1, 2014
                                    Decided and Filed: August 18, 2014

        BEFORE:           CLAY and STRANCH, Circuit Judges; BLACK, District Judge.*

                                             _________________

                                                  COUNSEL

ARGUED: Clinton L. Kelly, THE KELLY FIRM, Hendersonville, Tennessee, for Appellants.
Eric G. Lasker, HOLLINGSWORTH LLP, Washington, D.C., for Appellee. ON BRIEF:
Clinton L. Kelly, F. Dulin Kelly, THE KELLY FIRM, Hendersonville, Tennessee, for
Appellants. Eric G. Lasker, Katharine R. Latimer, HOLLINGSWORTH LLP, Washington,
D.C., Dwight E. Tarwater, PAINE, TARWATER, AND BICKERS LLP, Knoxville, Tennessee,
for Appellee.




        *
          The Honorable Timothy S. Black, United States District Judge for the Southern District of Ohio, sitting by
designation.




                                                         1
No. 13-6266         Payne, et al. v. Novartis Pharm. Corp.                    Page 2

                                       _________________

                                           OPINION
                                       _________________

       JANE BRANSTETTER STRANCH, Circuit Judge. Charolette Payne and her husband
sued Novartis for failing to warn her doctor that two of the drugs it manufactures, Aredia and
Zometa, could cause serious damage to a patient’s jaw bones. Payne took both and subsequently
had to have part of her jaw removed. Under Tennessee law, the question of whether Novartis’s
failure to warn was a cause of Payne’s injuries is for a jury to determine. We therefore
REVERSE the district court’s grant of summary judgment for Novartis.

                                  I.      INTRODUCTION

       Answering the question presented by this failure-to-warn claim requires that we “unravel
the tangled skein of fact and policy” that goes by the deceptively unassuming name “causation.”
Wex S. Malone, Ruminations on Cause-in-Fact, 9 Stan. L. Rev. 60, 60 (1956). Causation issues
in failure-to-warn cases present particularly knotty problems. First, they involve a series of
counterfactual constructs—had you known certain facts, what would you have done?—that we
use to determine “cause in fact.” Restatement (Third) of Torts: Phys. & Emot. Harm § 28 cmt b.
Would the doctor have changed his behavior if he had known about the drug’s side effect? If so,
would the doctor’s actions have altered the patient’s? And would the patient’s altered actions
have reduced the harm the drug caused her? These, like all causation issues, are “ordinarily jury
questions, unless the uncontroverted facts and inferences to be drawn from them make it so clear
that all reasonable persons must agree on the proper outcome.” Haynes v. Hamilton Cnty.,

, 612 (Tenn. 1994); see also 63A Am. Jur. 2d Prod. Liab. §1138 (May 2014).

       Because the answers to such questions are essentially unknowable and clouded by
hindsight biases and credibility concerns (and thus especially suitable for the jury), at summary
judgment these kinds of cases often hinge on the mix of moral intuition and policy judgments we
call “proximate cause.” See Dobbs’ Law of Torts § 185; Waste Mgmt. Inc. of Tenn. v. S. Cent.
Bell Tel. Co., 

, 430 (Tenn. Ct. App. 1997). Plaintiffs must show, among other
things, that the drug manufacturer’s failure to warn was a “substantial factor” in the harm the
No. 13-6266           Payne, et al. v. Novartis Pharm. Corp.                      Page 3

drug caused the patient. Hale v. Ostrow, 

, 719 (Tenn. 2005). This is also
normally a question for the jury. See 

. The legal significance of the
warning’s absence may also be dependent on particular facts such as dosage prescribed,
prescription time frame, the patient’s medical profile—to list a few common considerations.

        Not only are these cases enormously fact-specific and fact-intensive, they are state-
specific: the same set of facts that could get a plaintiff to the jury in one jurisdiction could very
well result in summary judgment for the drug manufacturer in another. Woe to the party in a
failure-to-warn case who thinks that cases from other jurisdictions will guarantee victory in her
own. States have adopted a variety of legal rules that simplify the causation analysis; some rules
benefit the pharmaceutical company (and shift liability to the prescribing doctor), some the
injured patient. See, e.g., Giles v. Wyeth, Inc., 

, 1065–69 (S.D. Ill. 2007); see
also Garside v. Osco Drug, Inc., 

, 82–83 (1st Cir. 1992); 1 Madden & Owen on
Prod. Liab. § 9:11 (3d ed. 2000).

        Here, two factual issues carry the plaintiffs past summary judgment: Payne’s doctor
made clear that he would have warned Payne had he known that Aredia and Zometa can destroy
a patient’s jaw bones, and Payne testified that she would not have taken the drugs had she been
aware of the risk of this side effect.

                                         II.   BACKGROUND

        Aredia and Zometa “are prescription biophosphonate drugs produced by Novartis that are
given intravenously, most often to patients with cancerous conditions. The drugs are effective as
preventing pathological fractures . . . and other bone pains.” Patterson v. Novartis Pharm.
Corp., 451 F. App’x, 495, 496 (6th Cir. 2011). They are, however, associated with osteonecrosis
of the jaw (ONJ). “Osteonecrosis of the jaw results in the gums being eaten away until the bone
is exposed” and then dies from lack of blood. 

between biophosphonates and
ONJ began to come to light to the medical community in the early 2000’s. Courts in other
bisphosphonate cases found to be probative evidence that Novartis was aware of the risk of ONJ
years earlier. See, e.g., Mahaney ex rel. estate of Kyle v. Novartis Pharm. Corp., 

, 311 (W.D. Ky. 2011); Rowland v. Novartis Pharm. Corp., --- F.Supp.2d ----, 

, at *3 (W.D. Penn. 2014). Other ONJ plaintiffs have “presented evidence showing that
No. 13-6266         Payne, et al. v. Novartis Pharm. Corp.                     Page 4

Novartis’s high-ranking officials knew about the drugs’ side effects and subverted medical
inquiries into such effects.” Fussman v. Novartis Pharm. Corp., 509 F. App’x 215, 224 (4th Cir.
2013) (per curiam); see also Davids v. Novartis Pharm. Corp., 

, 183
(E.D.N.Y. 2013). “Novartis knew of the risk of ONJ as early as 2002, but instructed its sales
force not to mention the disease when making calls to physicians.” Winter v. Novartis Pharm.
Corp., 

, 409 (8th Cir. 2014).

       In 1999 Charolette Payne’s breast cancer spread to her bones. That same year, her
physician, Dr. Darrell Johnson, prescribed Aredia, unaware of the risk of the ONJ. In 2001, Dr.
Johnson switched her to Zometa; again, Dr. Johnson was not aware of the risk of ONJ. In 2005,
Dr. Johnson noticed something wrong with Payne’s jaw and advised her to see a dentist. He also
suspended her Zometa treatment. He later explained why:

       There were some data coming out about that time that Aredia and Zometa can be
       associated with complications of the mandible that can increase the risk of what
       we call osteonecrosis of that jaw and I believe that—you know, within a year or
       so of that there were some data coming out and saying that if you have a patient
       that you’re suspicious of something like that possibly going on[,] holding the
       medication may be wise while they’re undergoing evaluation by a dentist.

       Payne had several teeth removed but “was displeased with her oral surgeon’s
performance and continued to feel pain in the area from which her teeth were extracted.” In
2007, Dr. Johnson noticed that one of Payne’s teeth was partially necrotic. Payne’s oral surgeon
diagnosed her with biophosphonate-induced ONJ. Her condition progressed; part of Payne’s jaw
had to be removed in 2009.

       “Had I been warned that Aredia and Zometa may cause Osteonecrosis of the jaw, I would
not have taken those drugs,” Payne later stated in an affidavit. Dr. Johnson testified that he
continues to prescribe Aredia and Zometa but now warns his patients about the risk of ONJ and
recommends that they get a dental exam before they start treatment.

       Payne and her husband sued Novartis in 2008, alleging in relevant part that her ONJ was
the result of Novartis’s failure to provide adequate warnings about the link between
biophosphonates and the disease. Payne’s was one of many such suits. The judicial panel on
multidistrict litigation transferred her case to the Middle District of Tennessee for consolidated
No. 13-6266           Payne, et al. v. Novartis Pharm. Corp.                      Page 5

proceedings. The MDL court remanded her case in March 9, 2012, and it was subsequently
transferred to the Eastern District of Tennessee.

        The district court granted summary judgment for Novartis on one ground: That
Novartis’s alleged failure to warn was not a proximate cause of Payne’s ONJ.                Under
Tennessee’s “learned intermediary doctrine,” the court stated, the question was whether a jury
could find that Dr. Johnson would have done something differently had he known about the risk
of ONJ and, if so, whether that difference could have prevented Payne’s ONJ. The court
dismissed as “entirely speculative” Payne’s statement that she would have refused
biophosphonates if she had been warned about the risk of ONJ.

        On appeal, the Paynes argue that a jury could find that Payne would not have developed
ONJ if Novartis had warned Dr. Johnson about the risk.                    The Paynes’ argument is
straightforward: If Novartis had warned Dr. Johnson, Dr. Johnson would have warned Payne
and Payne would have refused to take biophosphonates.                  Novartis focuses on what it
characterizes as the district court’s evidentiary decision to “exclude” Payne’s statement that she
would not have taken Aredia or Zometa had she known the risk. As Novartis’s counsel said at
oral argument, this case “does rise and fall on whether or not the district court acted within its
discretion . . . to disregard the affidavit as being entirely speculative.”

                                        III.    DISCUSSION

    A. Standard of Review

        The panel reviews the district court’s grant of summary judgment de novo. Laster v. City
of Kalamazoo, 

, 726 (6th Cir. 2014). Summary judgment is appropriate only if the
pleadings, depositions, answers to interrogatories, and affidavits show there is no genuine issue
as to any material fact and the moving party is entitled to judgment as a matter of law.
Fed.R.Civ.P. 56(a) & (c). The burden to show that there are no genuine issues of material fact
falls on the parties seeking summary judgment. Celotex Corp. v. Catrett, 

, 322–23,
(1986). “Credibility determinations, the weighing of the evidence, and the drawing of legitimate
inferences from the facts are jury functions, not those of a judge[.]” Anderson v. Liberty Lobby,
Inc., 

, 255 (1986). We consider the evidence in the light most favorable to the non-
No. 13-6266          Payne, et al. v. Novartis Pharm. Corp.                     Page 6

moving parties, drawing all justifiable inferences in their favor. 

question is
whether the evidence presents a sufficient factual disagreement to require submission of the case
to the jury, or whether the evidence is so one-sided that the moving parties should prevail as a
matter of law. 

       We sit in diversity and must apply Tennessee substantive law. Hayes v. Equitable
Energy Res. Co., 

, 566 (6th Cir. 2001). In resolving issues of Tennessee law, we
look to “the final decisions of that state’s highest court, and if there is no decision directly on
point, then we must make an Erie guess to determine how that court, if presented with the issue,
would resolve it.” Conlin v. Mortg. Elec. Registration Sys., Inc., 

, 358–59 (6th Cir.
2013). The decisions of the Tennessee Court of Appeals “are also viewed as persuasive unless it
is shown that the state’s highest court would decide the issue differently.” 

v. Access Grp., Inc., 

, 762 (6th Cir. 2008)).

   B. The Learned Intermediary Doctrine

       “[M]anufacturers of prescription drugs, like manufacturers of any other unavoidably
dangerous product, have a duty to market and distribute their product in a way that minimizes the
risk or danger.” Pittman v. Upjohn Co., 

, 428 (Tenn. 1994). Prescription drug
manufacturers typically fulfill their duty by warning “those who foreseeably could be injured by
the use of their products” of any harmful side effects. 

had a continuing duty to
warn the users of Aredia and Zometa about the side effects of these “unavoidably dangerous”
products. 

“the learned intermediary doctrine is applicable in failure to warn suits
where a physician is the intermediary between a defendant pharmaceutical . . . manufacturer and
an injured patient.” Nye v. Bayer Cropscience, Inc., 

, 701 (Tenn. 2011). “The
doctrine constitutes a defense by pharmaceutical manufacturers in cases where a plaintiff has
suffered injury from a medication prescribed by a doctor.”            

drug
manufacturer’s duty to warn can be discharged if it provides adequate warnings to the physican
regarding the drug’s risk. 

is based on the understanding that physicians play a
“pivotal role . . . in the unique system used to distribute prescription drugs,” and can stand
between the drug manufacturer and the patient. 

. At base, the
No. 13-6266          Payne, et al. v. Novartis Pharm. Corp.                     Page 7

doctrine can shift liability from drug companies to doctors: If the drug company adequately
warned and instructed the doctor but the doctor did not adequately warn and instruct the patient,
the patient’s quarrel is with the doctor rather than the drug company. See State ex rel. Johnson &
Johnson Corp. v. Karl, 

, 917–18 (W.Va. 2007) (Maynard, J., concurring); Victor
E. Schwartz et al., Marketing Pharmaceutical Products in the Twenty-First Century, 32 Harv.
J.L. & Pub. Pol’y 333, 367–69 (2009).

       Ostensibly applying the learned intermediary doctrine, the district court concluded that
Novartis was entitled to summary judgment. The court determined that the Paynes could not
show that Novartis’s failure to warn had proximately caused Charolette’s injury for two
reasons—her doctor would not have meaningfully changed his prescribing practice had he been
aware of the risk of the drugs and Charolette’s affidavit testimony that she would have refused
the drugs had she been aware of the risk was “speculative.” We disagree on both counts.

       Dr. Johnson testified that he now (1) warns patients about the risk of ONJ and
(2) recommends that they see a dentist before staring biophosphonates.          The district court
correctly noted that there was no evidence that a dental exam in 1999 (when Payne started
Aredia) or 2001 (when she switched to Zometa) would have prevented her ONJ. But the district
court disregarded the import of Dr. Johnson’s testimony that he now warns patients about the
risk of ONJ, and in this respect the court erred. See Smith v. Pfizer, Inc., 

, 746
(M.D. Tenn. 2010) (applying Tennessee law) (denying summary judgment for Pfizer because, in
part, of evidence that the decedent’s doctor would have warned him about the risk of suicide).

       Payne stated in her affidavit that she would not have taken either drug if she had been
aware of the risk of ONJ. Viewed in the light most favorable to the Paynes, a factfinder could
infer that, had he known the risk, Dr. Johnson would have warned Payne about ONJ before
starting her on Aredia or Zometa and Payne would have then refused to take the drugs. But the
district court considered Payne’s affidavit testimony to be “entirely speculative” and therefore
insufficient to prevent summary judgment. Novartis frames this conclusion as “an evidentiary
ruling” that the panel reviews for abuse of discretion; we read the court’s decision as simply an
application of the summary judgment standard. The court did not “exclude” the affidavit; rather,
it determined that the affidavit was not “significantly probative” and could not provide a basis
No. 13-6266          Payne, et al. v. Novartis Pharm. Corp.                      Page 8

for the Paynes to survive summary judgment. 

. As this is a diversity
case, the probative value of the affidavit is determined by Tennessee law. See McLean v. 988011
Ontario, Ltd., 

, 800 (6th Cir. 2000).

       All Tennessee law requires is evidence that a warning would have altered the doctor’s
actions and that the change in the doctor’s actions would have averted the patient’s injury. “The
key inquiry is whether, ‘had additional warnings been given, the plaintiff[] would not have
sustained [her] injuries.’” 

(quoting King v. Danek, 

,
453 (Tenn. Ct. App. 2000)); see also Cansler v. Grove Mfg. Co., 

, 1511 (6th Cir.
1987). Courts in other jurisdictions have considered a plaintiff’s testimony that she would not
have taken the drug if she had been warned of its side effects to be sufficient to prevent summary
judgment. See, e.g., Gilliland v. Novartis Pharm. Corp., --- F.Supp.2d ----, 

,
at *8 (S.D. Iowa 2014) (“The learned intermediary doctrine certainly does not allow health care
professionals to substitute their judgment for that of their patients. Nor does it obviate the need
to consider whether the plaintiff patient's decision concerning her recommended course of
treatment would have been different, assuming that the warning at issue had been more
adequate.”); In re Aredia and Zometa Prod. Liab. Litg. (Hogan), No. 3:06-MD-1760, 

, at *2 (M.D. Tenn. Aug. 19, 2009) (applying Rhode Island law); see also Fussman, 509
F. App’x at 224. Other cases have not found such testimony from the plaintiff to be sufficient.
See, e.g., Luttrell v. Novartis Pharm. Corp., 

, 1344–45 (E.D. Wash. 2012).

       Neither the district court nor the parties have identified a Tennessee case that supports the
proposition that this testimony is insufficient to forestall summary judgment. To the contrary,
the Paynes note that Tennessee explicitly allows such testimony to show causation in informed
consent cases. See Ashe v. Radiation Oncology Assocs., 

, 123–24 (Tenn. 1999)
(“The finder of fact may consider and give weight to the patient’s testimony as to whether the
patient would have consented to the procedure upon full disclosure of the risks.”). Causation in
both types of cases—informed consent and failure to warn—ultimately rests with the patient’s
decision to take or reject the medication. Both types of cases address the same issue, and we can
find no indication that the Tennessee Supreme Court would adopt a different standard of proof
for essentially the same link in the causal chain. Cf. Aaron D. Twerski & Neil B. Cohen,
No. 13-6266         Payne, et al. v. Novartis Pharm. Corp.                     Page 9

Resolving the Dilemma of Nonjusticiable Causation in Failure-to-Warn Litigation, 84 S. Cal. L.
Rev. 125, 128 (2010) (“In both informed consent and failure-to-warn cases, (1) the plaintiff has
acted without information that perhaps would have led to a different decision, and (2) . . . the
cause of action requires the plaintiff to demonstrate that a different (and less harmful) decision
would have been made had that information been provided.”).

       Both parties cite to a number of biophosphonate cases in other jurisdictions where the
patient stated that she would not have taken the medication if she had known of the risk of ONJ.
These cases may give the reader a sense of both the various fact patterns involved in
biophosphonate litigation and the difficulty in dealing with counterfactual testimony. Compare,
e.g., D’Agnese v. Novartis Pharm. Corp., 

, 892–93 (D. Ariz. 2013) with
Bowles v. Novartis Pharm. Corp., No. 3:12-cv-145, 

, at *12–13 (S.D. Ohio
Sept. 19, 2013) (specifically rejecting Payne); see also Kruszka v. Novartis Pharm. Corp, --- F.
Supp. 2d. ----, 

at *15 (D. Minn. 2014) (distinguishing D’Agnese). But they are
not particularly helpful in answering whether Payne’s affidavit testimony might prevent
summary judgment for Novartis under Tennessee substantive law. Although many states have
adopted the learned intermediary doctrine, the doctrine differs significantly from state to state
when it comes to causation. See e.g., Karin L. Bohmoldt, The Heeding Presumption and Its
Application, 37 Loy. L.A. L. Rev. 461, 461–62 (2003). There appear to be two major categories.
Some states have a rebuttable presumption of causation if a drug company failed to provide a
warning. See, e.g., Bee v. Novartis Pharm. Corp., --- F. Supp. 2d ----, 

at *12
(E.D.N.Y. 2014); see also Coffman v. Keene Corp., 

, 718 (N.J. 1993) (discussing
the reasons for and against adopting the presumption of causation).          In other states the
presumption is that the doctor would have “heeded” the warning but these states do not then
presume that the failure to warn actually caused the plaintiff’s injury. See, e.g., Ingram v.
Novartis, 

, 1244 (W.D. Okla. 2012). At least one state appears to have
swung to the extreme, essentially presuming that the patient would have done whatever her
doctor said. See Willett v. Baxter Int’l, Inc., 

, 1098–99 (5th Cir. 1991) (applying
Louisiana law).
No. 13-6266          Payne, et al. v. Novartis Pharm. Corp.                      Page 10

       Tennessee has not adopted any of these presumptions. It does, however, normally accept
the kind of evidence that the district court rejected as “speculative.” See 

–
24. Although the record is relatively spare, causation is a question for the jury “unless the
uncontroverted facts and inferences to be drawn from them make it so clear that all reasonable
persons must agree on the proper outcome.” 

. We cannot say that all
reasonable people must agree that a warning from Novartis would not have significantly changed
Dr. Johnson’s actions and prevented Payne’s ONJ. In this case, under Tennessee law, causation
is an issue for the jury and the district court erred in concluding otherwise.

                                      IV.     CONCLUSION

       Novartis argued that this case “rise[s] and fall[s]” on whether the district court properly
disregarded Payne’s affidavit testimony. Under Tennessee law, Payne’s testimony, combined
with her doctor’s, could establish a sufficient causal link between Novartis’s failure to warn and
Payne’s jaw death. A reasonable jury could conclude that Payne would not have taken Aredia or
Zometa had Dr. Johnson warned her of the risk of ONJ. We REVERSE the district court’s grant
of summary judgment for Novartis and remand the case for further proceedings consistent with
this opinion.