Court Opinion

ID: 167924
Source: CourtListenerOpinion
Date Created: 2010-08-14 10:06:31+00
Date Added: 2024-06-11T17:24:55.082464
License: Public Domain

F I L E D
                                                                   United States Court of Appeals
                                                                           Tenth Circuit
                       UNITED STATES CO URT O F APPEALS
                                                                         August 8, 2006
                               FO R TH E TENTH CIRCUIT                Elisabeth A. Shumaker
                                                                          Clerk of Court

    W E N DIE H . TIN G EY ,

                  Plaintiff-Appellant,

      v.                                                   No. 04-4216
                                                    (D.C. No. 2:02-CV -710-TS)
    RADIONICS, a division of Tyco                           (D. Utah)
    Health Care Group LP, a Utah
    corporation,

                  Defendant-Appellee.

                               OR D ER AND JUDGM ENT *

Before KELLY, SE YM OU R, and M U RPH Y, Circuit Judges.

           After examining the briefs and appellate record, this panel has determined

unanimously that oral argument would not materially assist the determination of

this appeal. See Fed. R. App. P. 34(a)(2); 10th Cir. R. 34.1(G). The case is

therefore ordered submitted without oral argument.

*
      This order and judgment is not binding precedent, except under the
doctrines of law of the case, res judicata, and collateral estoppel. The court
generally disfavors the citation of orders and judgments; nevertheless, an order
and judgment may be cited under the terms and conditions of 10th Cir. R. 36.3.
      This is a products liability action alleging that plaintiff-appellant,

W endie H. Tingey, suffered injury from a defective product manufactured by

defendant Radionics. M s. Tingey appeals from the district court’s order striking

the affidavit of her expert witness; striking the second deposition of her

physician; denying her motion for summary judgment; and granting Radionics’

motion for summary judgment. W e affirm in part, reverse in part, and remand for

further proceedings.

                                       FACTS

      1. M s. T ingey’s back problem s

      M s. Tingey suffered from long-standing back pain, exacerbated by a

previous surgical fusion of her lower vertebrae. She sought treatment from an

anesthesiologist, Dr. Richard Rosenthal. After treatment with pain medication

and anesthetic nerve blocks proved unsatisfactory, M s. Tingey agreed to undergo

a “nerve ablation procedure” designed to isolate and destroy the nerves causing

her pain.

      2. The radiofrequency device

      This procedure was performed by Dr. Rosenthal, accompanied by a nurse,

using a radiofrequency lesion generator, model RFG -3C+ (the “device” or

“radiofrequency device”) manufactured by Radionics. Dr. Rosenthal was

well-experienced in use of the radiofrequency device, as was the nurse who

                                          -2-
assisted him. The device is designed to therapeutically destroy painful nerve

tissue by creating lesions in the tissue.

      The Radionics radiofrequency device used by Dr. Rosenthal on M s. Tingey

required him to insert a hollow needle into her back. An electrode was then

inserted into the needle to produce the radiofrequency waves. The device was

designed to operate in two basic modes, lesioning and stimulation mode.

      3. Lesioning vs. stimulation mode

      In its high-voltage, lesioning mode (also known as the “pulse mode”), the

device destroys nerve tissue. In order to locate the precise nerve tissue to be

destroyed, however, the device also has a lower-voltage, nerve stimulation mode

(sometimes called “stim mode”). W hen operating in the stim mode, the device

delivers a low-voltage current to nerve tissue so that the patient can feel the tingle

it produces in the nerves and advise the physician when he has positioned the

needle adjacent to the painful nerve tissue to be lesioned. The usual procedure is

to use the stim mode to locate the tissue to be lesioned, and then to sw itch over to

pulse mode to actually destroy nerve tissue.

             a. H igh and low frequency stimulation

      The stim mode, in turn, requires the use of two settings, which are

controlled by a rate-select button. The higher-frequency setting (50 Hz) is used

to stimulate the sensory part of the nerve. A lower-frequency setting (2 Hz) is

used to stimulate the motor portion of the nerve.

                                            -3-
             b. Voltage adjustments

      There are also voltage adjustments to be made w ithin the stim mode. These

adjustments allow the operator to position the needle as close as possible to the

affected nerve. The closer the needle is to the affected tissue, the less voltage is

required to detect the nerve. The physician can tell that the needle is positioned

correctly when only a small amount of voltage is needed to produce a tingling

sensation on the affected nerve. If a higher voltage is required to produce

sensation, he may need to reposition the needle closer to the nerve before

beginning to lesion it.

      The voltage is controlled by two switches located on the front panel of the

device. One sw itch is a rheostat or potentiometer similar to a dimmer sw itch for a

light fixture, which allows the operator to increase the output voltage in slow

increments. The other is a toggle switch that immediately increases the voltage

ten-fold, from a range of zero to one volt to a range of one to ten volts.

      High-frequency sensory stimulation (50 Hz) is performed uniquely at a low

voltage (zero to one volt maximum), while low-frequency motor stimulation

(2 Hz) is done only at a higher voltage (one to ten volts). W hen the operator

wants to switch from stimulating the sensory portion of a nerve to stimulating the

motor portion of the nerve, he must activate two switches: the rate select switch

(stepping down the frequency from 50 Hz to 2 Hz), and the voltage toggle switch

(stepping up from the zero to one volt mode to the one to ten volt mode). The

                                         -4-
same is true in reverse, when switching from motor to sensory mode. There, the

operator would step up the frequency from 2 Hz to 50 Hz, and step down the

voltage range to zero to one volt.

             c. Potential dangers and safety mechanisms provided

      The frequency switch, but not the voltage-toggle switch, has a fail-safe

mechanism. If the operator attempts to switch between frequencies and the

voltage control knob has not been set to zero, the machine shuts itself down. The

voltage toggle switch, however, contains no such fail-safe device.

      If the voltage is not set at zero when the voltage toggle switch is flipped, it

allows for a sudden, ten-fold spike in electrical current into the patient, without

automatic shutoff. The operator can avoid this sudden, ten-fold increase in

voltage in one of two ways. First, he can reset the voltage control to zero before

switching the toggle switch. In fact, operators are trained to reset to zero voltage

before making changes to the device’s output. Second, if he forgets to do that,

but if he activates the switches in the order frequency first, voltage second, the

fail-safe mechanism associated with the rate select switch will shut the device

down. In fact, any attempt to change frequency while the voltage knob is not at

zero results in the device immediately shutting down.

                                         -5-
             d. M s. Tingey’s operation

      In M s. Tingey’s case, she alleges that the nurse operating the device made

two crucial errors, when the physician told her to switch from sensory to motor

stimulation. First, she did not turn the voltage control to zero. Second, she

immediately switched the toggle switch, to increase the voltage ten-fold, rather

than the rate-select switch, to adjust the frequency. Because of this, the fail-safe

mechanism that would have engaged had she activated the rate-select sw itch with

a non-zero current did not prevent an instant ten-fold increase in the amount of

electricity flowing through the needle.

      As a result, M s. Tingey received an electrical shock of approximately seven

volts, at a frequency of 50 Hz. She jumped and screamed out in pain. Later that

day, she found that she was unable to urinate and defecate normally. Her fecal

incontinence resolved soon thereafter, but she was left with an apparently

permanent form of urinary incontinence known as “neurogenic bladder.” This

means that she cannot sense when her bladder is full, and that her bladder does

not empty properly. As a result, she must self-catheterize to empty her bladder.

      4. The district court’s sum mary judgment decision

      M s. Tingey’s complaint alleged causes of action for strict products liability,

negligence, and failure to w arn. The parties filed cross motions for sum mary

judgment. The district court (1) struck the affidavit of M s. Tingey’s expert

witness, Dr. M cKay Platt; (2) struck the second deposition of Dr. Rosenthal, the

                                          -6-
physician who performed the lesioning procedure; (3) denied M s. Tingey’s

motion for summary judgment; and (4) granted R adionics’ motion for summary

judgment.

      The district court gave two reasons for granting Radionics’ motion as to

M s. Tingey’s strict liability cause of action. First, there was no evidence to

support M s. Tingey’s claim that the device caused her injuries. Second,

M s. Tingey did not meet her burden of coming forward with evidence that the

device was unreasonably dangerous or that an alternative safer design was

practicable. The district court also rejected her failure to warn claim, finding that

the nurse who operated the device had been properly trained and knew how the

switch in question operated. Finally, the district court found no credible evidence

that Radionics breached any duty owed to M s. Tingey that would support her

negligence claims.

                            STANDA RD O F REVIEW

      W e review the district court’s order granting summary judgment
      under the same standard employed by the district court under
      Rule 56(c) of the Federal Rules of Civil Procedure. Summary
      judgment is proper only if there is no genuine issue of material fact
      for determination, and the moving party is entitled to judgment as a
      matter of law. W e review the entire record on summary judgment de
      novo in the light most favorable to the party opposing summary
      judgment.

Durham v. Herbert Olbrich GM BH & Co., 404 F.3d 1249, 1250 (10th Cir. 2005)

(quotation omitted). “In cases such as this, where the nonmoving party will bear

                                          -7-
the burden of proof at trial on a dispositive issue[,] that party must go beyond the

pleadings and designate specific facts so as to make a showing sufficient to

establish the existence of an element essential to that party’s case in order to

survive summary judgment.” Garrett v. Hewlett-Packard Co., 305 F.3d 1210,

1216 (10th Cir. 2002) (quotations omitted).

                                     ANALYSIS

      1. Strict liability – design defect

      To prove her strict product liability claim based on defective design,

M s. Tingey must show

      (1) that the [device] was unreasonably dangerous due to a defect or
      defective condition, (2) that the defect existed at the time the product
      was sold, and (3) that the defective condition was a cause of the
      plaintiff’s injuries.

Brown v. Sears, Roebuck & Co., 328 F.3d 1274, 1279 (10th Cir. 2003) (quotation

omitted). The district court concluded that she failed to establish the first and

third elements. W e begin with the first element, whether the Radionics device

was defectively designed, and therefore unreasonably dangerous. W e address

causation in a separate section of this order and judgment, because it impacts each

of M s. Tingey’s claims.

             a. O bjective and subjective tests–overview

      A plaintiff alleging that a product is “unreasonably dangerous” must satisfy

both an objective and a subjective component. Id. at 1282. The objective

                                          -8-
component asks whether the product is “dangerous to an extent beyond which

would be contemplated by the ordinary and prudent buyer, consumer or user of

that product in that community considering the product’s characteristics,

propensities, risks, dangers and uses.” Utah Code Ann. § 78-15-6(2). “The issue,

roughly speaking, is whether an ordinary person w ould think the product is less

dangerous than it is.” Brown, 328 F.3d at 1280.

      The subjective component requires the court to consider “any actual

knowledge, training, or experience possessed by that particular buyer, user or

consumer.” Utah Code Ann. § 78-15-6(2). Since the subjective component

involves knowledge that increases a particular buyer, user or consumer’s ability

to understand the dangers associated with the product, it can only raise the

standard that the plaintiff must meet in a particular case. Brown, 328 F.3d at

1282. If the particular buyer, user or consumer has no specialized knowledge, of

course, the plaintiff has no additional burden to meet for this element.

             b. O bjective test–analysis

      M s. Tingey contends that the Radionics device is unreasonably dangerous

from an objective standpoint because “an ordinary and prudent Anaesthesiologist

would have no meaningful way of knowing the toggle switch could be flipped-up

into the ‘high’ position (0 to 10 volts), and the Device would instantly deliver to

the patient a continuous electrical impulse 10-times greater than intended.” A plt.

Opening Br. at 26 (emphasis in original). Radionics counters, first, that the

                                         -9-
device has been approved by the Food and Drug Administration (FD A), and

second, that an ordinary and prudent user of the device would have appreciated

the dangers of improperly activating the toggle switch without turning down the

power knob. Radionics further notes that the device has been widely used for

twenty years w ithout any complaint that its design or the design of its toggle

switch is in any way dangerous or defective.

                    (1.) Statutory presum ption

      Radionics contends that it is entitled to a presumption created by Utah’s

Product Liability Act, which sets limits on suits for product defects. That statute

reads in pertinent part:

      In any action for damages for personal injury, death, or property
      damage allegedly caused by a defect in a product:

      [. . .]

      (3) There is a rebuttable presumption that a product is free from any
      defect or defective condition where the alleged defect in the plans or
      designs for the product or the methods and techniques of
      manufacturing, inspecting and testing the product were in conformity
      with government standards established for that industry which w ere
      in existence at the time the plans or designs for the product or the
      methods and techniques of manufacturing, inspecting and testing the
      product were adopted.

Utah Code Ann. § 78-15-6.

      Radionics cites a letter ruling it obtained from the FDA permitting it to

market the device. See Aplt. App., Vol. I, at 70-71. It contends that this letter

ruling entitles it to the rebuttable presumption in § 78-15-6(3) that the device “is

                                         -10-
free from any defect or defective condition.” M s. Tingey responds that Radionics

is not entitled to the presumption because the FDA never tested the device, and

because there were no FDA requirements regarding the labeling of devices of this

type.

        In Slisze v. Stanley-Bostitch, 979 P.2d 317 (Utah 1999), the Utah Supreme

Court indicated that § 78-15-6(3) should be read in light of the Restatement

(Second) of Torts § 285 (1965), which permits courts to determine the standard of

reasonable care to be followed by reference to an administrative regulation. See

id. at 321. Section 286 of the same Restatement provides specific guidelines for

the use of administrative regulations to establish the standard of care. It states

that a court may adopt the standard contained in an administrative regulation

whose purpose is “(a) to protect the class of persons which includes the one

whose interest w as invaded, and (b) to protect the particular interest w hich is

invaded (c) to protect that interest against the kind of harm which has resulted,

and (d) to protect that interest against the particular hazard from which the harm

results.” An administrative regulation that meets these requirements can be used

to establish the presumption of non-defectiveness under § 78-15-6(3). Slisze,

979 P.2d at 321.

        The question before us, therefore, is whether the FDA approval that

Radionics received satisfied the standards identified in the Restatement test, and,

hence, those required for the application of § 78-15-6(3). The FDA letter ruling

                                         -11-
at issue granted Radionics’ “Section 510(k)” application to market the

radiofrequency device that allegedly injured M s. Tingey. The section referenced

is part of the M edical Device Amendments of 1976 to the Federal Food, Drug and

Cosmetic Act (M DA), codified at 21 U.S.C. § 360(k). Section 510(k) requires

persons seeking to introduce into interstate commerce a device intended for

human use to report to the Secretary of H ealth and H uman Services the class

under w hich the device is classified and the person’s actions taken to comply with

requirements under 21 U.S.C. § 360d or 360e.

      W ith regard to the “class under which the device is classified,” the

Supreme Court has explained that

      [t]he Act classifies medical devices in three categories based on the
      risk that they pose to the public. Devices that present no
      unreasonable risk of illness or injury are designated Class I and are
      subject only to minimal regulation by “general controls.” 21 U.S.C.
      § 360c(a)(1)(A). Devices that are potentially more harmful are
      designated Class II; although they may be marketed without advance
      approval, manufacturers of such devices must comply with federal
      performance regulations known as “special controls.”
      § 360c(a)(1)(B). Finally, devices that either “presen[t] a potential
      unreasonable risk of illness or injury,” or which are “purported or
      represented to be for a use in supporting or sustaining human life or
      for a use which is of substantial importance in preventing impairment
      of human health,” are designated Class III. § 360c(a)(1)(C).

M edtronic, Inc. v. Lohr, 518 U.S. 470, 476-77 (1996).

      Before the device was introduced into interstate commerce, therefore,

Radionics would ordinarily have had to comply with the requirements for a Class

                                        -12-
II device noted in 21 U.S.C. § 360d. These requirements are much less rigorous

than the requirements for obtaining premarket approval (PM A) for a Class III

device. 1 And in this case, Radionics received additional relief from the regulatory

requirements, because the FDA determined that the device was substantially

equivalent to devices marketed in interstate commerce on or before M ay 28, 1976,

and therefore entitled to be “grandfathered” in as safe. Therefore, Radionics was

only required to comply with the general controls provisions of the A ct before

marketing the device. Aplt. A pp., Vol. I, at 70.

      These general controls do incorporate a safety rationale. The statutory

definition of Class I General Controls specifically includes any combination of

such controls “sufficient to provide reasonable assurance of the safety and

effectiveness of the device.” 21 U.S.C. § 360c(a)(1)(A). M oreover, the

regulations dealing with the content and format of a § 510(k) summary require a

person intending to use the device for a different purpose than that prescribed for

its equivalent to explain “why the differences do not affect the safety and

effectiveness of the device when used as labeled.” 21 C.F.R. § 807.92(a)(5). See

also M edtronic, 518 U.S. at 491 (stating “primary issue motivating the M DA’s

enactment” was “the safety of those who use medical devices”).

1
      “In contrast to the 1,200 hours necessary to complete a PM A review, the
§ 510(k) review is completed in an average of only 20 hours.” M edtronic,
518 U.S. at 479.

                                        -13-
      On the other hand, as the Supreme Court has explained in the preemption

context, the § 510(k) process is focused on equivalence rather than safety, and

therefore “provide[s] little protection to the public.” Id. at 493. W hile the FDA

examines § 510(k) applications with a general concern for safety and

effectiveness, it does not require devices approved under that section to take any

particular form; the device must merely be substantially equivalent to one that

existed before 1976, “marketed without running the gauntlet” of M DA. Id. at

494. Cf. also Talley v. Danek Medical, Inc., 179 F.3d 154, 161 (4th Cir. 1999)

(holding, in negligence per se context, that requirement for pre-market approval

under the M DA “lacks any independent substantive content,” failure to comply is

“analogous to the failure to have a drivers license,” and M DA does not establish

the standard of care). Because the M DA approval Radionics received, that of

substantial equivalence to a pre-1976 device, did not result from its compliance

with a regulatory standard meeting the Restatement test, we conclude that

Radionics is not entitled to the presumption in § 78-15-6(3) that the device “is

free from any defect or defective condition.”

                   (2.) Actual vs. perceived dangers of device

      M s. Tingey notes that the device is designed so that it automatically shuts

off if any change in output other than that created by operation of the toggle

switch is made w ithout first adjusting the pow er knob to zero. W hile the nurse

who operated the device testified that she was trained to turn the voltage down to

                                        -14-
zero before changing the output on the device, Radionics fails to point us to any

evidence that she was aware that the toggle switch was not protected by the

automatic shutoff safety mechanism, or that failing to zero out the voltage would

result in a harmful shock to the patient. 2   For this reason, we believe that

M s. Tingey has at least demonstrated a genuine factual issue concerning whether

the device was “more dangerous than an ordinary user would anticipate.” Brown,

328 F.3d at 1277.

             c. Subjective test-analysis

      Radionics emphasizes the specialized training and experience that both

Dr. Rosenthal and the nurse had with the device, and the specific training that the

nurse received to zero out the voltage before changing inputs. W hile this training

does raise the bar somewhat in terms of M s. Tingey’s burden, we nevertheless

conclude that she has met her burden of showing unreasonable dangerousness for

purposes of summary judgment. Even given their specialized training, Radionics

fails to point to anything in the training Dr. Rosenthal and the nurse received that

would have alerted them to the danger that resulted in M s. Tingey’s injuries.

2
      Radionics argues that the nurse “knew . . . that she needed to turn down the
power prior to engaging the toggle switch to prevent the patient from receiving a
shock.” Aplee Br. at 4 (emphasis added). The record citation it provides for this
statement, however, does not support Radionics’ contention that the nurse knew
that M s. Tingey would receive a harmful shock if the power switch were not
zeroed out w hen the toggle switch was activated.

                                          -15-
             d. Practicability of safer design

      Because M s. Tingey asserts that the Radionics device is defectively

designed, she must also satisfy a “risk-utility balancing test.” Brown, 328 F.3d at

1279. She does this by proving the practicability of a safer design. Id. M ore

specifically, in response to Radionics’ assertion that no evidence exists to satisfy

the “risk-utility balancing test,” M s. Tingey was responsible for coming forward

with evidence that “there w as an alternative, safer . . . design [for the device],

practicable under the circumstances, [that] was [technically] feasible” and that

would have prevented the accident that allegedly caused the injury to her bladder

nerves. Allen v. M innstar, Inc., 8 F.3d 1470, 1479 (10th Cir. 1993).

      Radionics asserts that an alternative design would not have been feasible,

because the toggle switch, unlike other sw itches on the device that control its

output, operates mechanically rather than being controlled by computer circuitry.

The toggle switch achieves its ten-fold differential by activating a series of

resistors that step the current down to the lower voltage. An engineer deposed in

the case opined that this use of a mechanical rather than computer-controlled

voltage adjustment would require a re-design of the entire unit to develop a

fail-safe mechanism that is digitally controlled. Aplt. App., Vol. II, at 520. It is

unclear whether such a re-design would even be feasible.

      M s. Tingey presented evidence, however, that the device could still

perform its essential functions, even if the toggle switch were eliminated. Id. at

                                         -16-
521. The toggle switch was provided primarily as a matter of convenience, to

permit fine tuning when the device operates in stim mode. Id. Dr. Rosenthal

testified that in his opinion, there was no medical reason why the toggle switch

could not be eliminated. Id., Vol. I, at 190. 3 Radionics represented to the

government, in support of its 510(k) application, that the device’s microprocessor

design made the unit safer than its predecessors. See id., Vol. II, at 357. If the

additional measure of safety afforded by the microprocessor failsafe design could

not in fact be achieved in the case of the toggle switch, a jury could find that a

safer alternative would be to eliminate the switch altogether. W e conclude that

M s. Tingey has made a sufficient showing of the practicability of a safer design

to survive summary judgment on this element of her strict liability claim.

3
        In such a case, apparently, the entire voltage range would be accessible and
controlled using the potentiometer. Fine voltage gradiations might be lost. Also,
it is unclear how the use of the frequency setting knob would be coordinated with
a single voltage control. Nevertheless, given Dr. Rosenthal’s extensive
experience with the device, and the other testimony of record that it operates
primarily as a convenience, we believe M s. Tingey has made a sufficient showing
on the “safer design” issue.

                                         -17-
         2. Duty to w arn claim

         Under Utah law, a manufacturer may also “be held strictly liable for any

physical harm caused by its failure to provide adequate warnings regarding the

use of its product.” House v. Armour of Am., Inc., 929 P.2d 340, 343

(Utah 1996). 4    “W here a manufacturer knows or should know of a risk associated

with its product, the absence or inadequacy of warnings renders that product

unreasonably dangerous, subjecting the manufacturer to strict liability.” Id.

(quotation omitted). M oreover, “[a] manufacturer . . . may have a duty to warn of

latent dangers even if there is no feasible way to produce a safer product; the

purpose of the warning is to enable the user to take appropriate steps to avoid the

hazard.” Wankier v. Crown Equipment Corp., 353 F.3d 862, 867 (10th Cir.

2003).

         In order to evaluate whether summary judgment was appropriate on

M s. Tingey’s “duty to warn” claim, we consider three questions: (1) W as there a

duty to warn? (2) W as the warning given adequate? and (3) Did the failure to give

the warning cause the plaintiff’s damages? See generally 2 Louis R. Frumer &

4
       Utah follows the “learned intermediary doctrine,” whereby it is the
manufacturer’s duty to warn the doctor of the dangers associated with a dangerous
drug, rather than the patient. See, e.g., Barson ex rel. Barson v. E.R. Squibb &
Sons, 682 P.2d 832, (Utah 1984). Courts have applied this doctrine to claims
involving medical devices, see Larkin v. Pfizer, Inc., 153 S.W .3d 758, 762
(Ky. 2004) (citing cases), and we assume U tah w ould do so as w ell. W e therefore
look, as the parties do, to the warnings provided to Dr. Rosenthal and/or the
nurse, rather than M s. Tingey.

                                         -18-
M elvin I. Friedman, Products Liability §§ 12.01 - 12.04 (2005); House, 929 P.2d

at 343-48 (analyzing three elements of duty to warn claim). W hile there is

limited authority in Utah dealing with these issues, case law from other

jurisdictions that recognize duty to warn claims, as well as commentary in the

Restatement (Third) of Torts – Products Liability, 5 provide useful guidance.

             a. W as there a duty to w arn?

      Radionics contends that it had no duty to warn because the danger was not

reasonably forseeable. No previous incidents of shock resulting in bladder

incontinence from use of the device had been reported. M oreover, the particular

output that harmed M s. Tingey was unintended and resulted only when the nurse

failed to follow proper operating directions. M s. Tingey responds that Radionics

was aware that unwanted output of the device could cause adverse and potentially

dangerous health effects. The danger from such outputs is demonstrated as a

general matter, she claims, by the shutoff mechanisms Radionics had installed on

other controls that changed the output from the device, which were absent in the

case of the toggle switch.

      A manufacturer has a duty to warn of potential dangers from both

reasonably forseeable use and misuse of a device. See, e.g., Huber v. Niagara

5
      W hile Utah has not formally adopted the Third Restatement, the principles
contained therein are similar but more fully developed than those described in the
Restatement (Second) of Torts § 402A, on which M s. Tingey’s “duty to warn”
cause of action is based.

                                        -19-
M achine & Tool Works, 430 N.W .2d 465, 467-68 (M inn. 1988). “[L]iability for

failure to instruct or warn attaches only if the risks presented by the product could

have been reduced by the adoption of reasonable instructions or w arnings . . . .

The post-sale conduct of the user may be so unreasonable, unusual, and costly to

avoid that a seller has no duty to design or warn against them.” Restatement

(Third) of Torts – Products Liability § 2, cmt. “p” (1998). Radionics makes much

of the multiple errors committed by the nurse in this case in her operation of the

device, contrary to her training. Courts have, however, extended the concept of

forseeable misuse even to accidents involving a combination of factors, such as

the accident resulting in M s. Tingey’s alleged injury.

      In Palmer v. Hobart Corp., 849 S.W .2d 135 (M o. Ct. App. 1993), for

example, the court upheld a verdict for the plaintiff on a duty to warn claim, after

the plaintiff was injured while cleaning a meat grinder. A label on the meat

grinder warned that it should not be operated without the guard over the cylinder

opening and the electric interlock in place. Id. at 137. The plaintiff was injured

after he left a w all switch on, “placed the adjusting ring on top of the grinder,

which inadvertently depressed the interlock device, thereby overriding the

interlock system; and . . . unintentionally pressed the foot pedal which started the

grinder.” Id. at 138. Thus, the operator made three separate mistakes, all of

which were required for the accident to have occurred, even though warned

                                          -20-
specifically about at least one of them. Notwithstanding his multiple errors, he

prevailed on his failure to warn claim.

      W e think M s. Tingey has demonstrated a question for a trier of fact

concerning Radionics’ duty to warn of the potential hazards associated with

flipping the toggle switch without first zeroing out the voltage on the device.

             b. W as the w arning adequate?

      Radionics contends that it provided an adequate warning because the nurse

who operated the device w as trained that she must zero out the voltage before

activating the toggle switch. M s. Tingey argues, however, that the real issue is

not whether the nurse knew how to operate the device, but whether she knew that

the toggle switch, alone among all devices adjusting output, was not designed so

that the device would automatically shut off if it was switched when the voltage

had not been previously adjusted to zero. She argues that this is a “hidden

danger” of the device’s toggle switch.

      The training the nurse received about zeroing out the voltage was an

instruction in proper use of the device, rather than a warning of the consequences

of misuse. “[T]here is a distinction betw een instructions and warnings . . . .

W arnings signal danger while instructions serve principally to provide the user

with information necessary to make proper and efficient use of the product.”

Palmer, 849 S.W .2d at 140-41(quotation omitted). M erely instructing a user on

how to use a product, without informing him or her of the dangers inherent in

                                          -21-
misuse, may constitute an inadequate warning of the product’s inherent dangers.

Scheman-Gonzalez v. Saber M f’g Co., 816 So. 2d 1133, 1140 (Fla. Ct. App.

2002). W hile the nurse here was instructed to zero the voltage before engaging

the toggle switch, Radionics has pointed to no evidence that she was informed of

the consequences of failing to follow this instruction. 6 W e conclude that

M s. Tingey has made an adequate showing to survive summary judgment on

whether the warning or instruction given in this case was adequate.

             c. Did the failure to w arn cause M s. Tingey’s injuries?

      W e discuss causation generally in the last section of this order and

judgment. The causation issue in this case basically concerns whether M s. Tingey

presented sufficient evidence to survive summary judgment that the shock she

received from the radiofrequency device caused her neurogenic bladder. In the

“duty to warn” context, however, a separate causation question is presented:

Could an adequate w arning have prevented M s. Tingey’s injury? “In any failure

to warn claim, a plaintiff must show that the failure to give an adequate warning

in fact caused the injury; i.e., that had warnings been provided, the injured party

would have altered his use of the product or taken added precautions to avoid the

6
       Dr. Rosenthal was aware that the purpose of the fail-safe feature on other
output controls of the device w as to prevent an unwanted shock, that could at very
least frighten the patient. See Aplt. App., Vol. I, at 189. He was surprised,
however, when M s. Tingey received the shock from the improper application of
the toggle switch. Id. He indicated that he had read the operator’s manual for
the device, and that nothing in it w arned him of this hazard. Id. at 193.

                                        -22-
injury.” House, 929 P.2d at 346. Radionics relies on the training the nurse

received to attempt to refute M s. Tingey’s claim that the lack of a warning caused

her injuries. As we have noted, however, this training did not substitute for an

adequate warning of the hidden dangers associated with the device.

      Utah law applies a heeding presumption. “[I]n cases in which it cannot be

demonstrated what the plaintiff would have done had he or she been adequately

warned, the plaintiff should be afforded a rebuttable presumption that he or she

would have followed an adequate warning had one been provided.” Id. at 347

(quotation omitted). The injury here resulted from a confessed mistake by the

nurse operating the controls of the Radionics device. Had she been adequately

warned of the dangers associated with the device, as opposed to merely being

taught how to operate it, we must presume that she would not have made the

error. Radionics has failed to rebut the heeding presumption applicable to this

case. W e conclude that M s. Tingey has adequately established each of the

elements of her “duty to warn” claim in a fashion sufficient to survive summary

judgment. 7

7
      To the extent that M s. Tingey has stated a claim for “negligent failure to
warn” in addition to a failure to warn claim sounding in strict liability, our
analysis also requires reversal of summary judgment on that claim.

                                        -23-
      3. Negligence

      Utah law permits a plaintiff simultaneously to bring both strict products

liability and negligence claims. Slisze, 979 P.2d at 319. To establish a

negligence claim, the plaintiff must show: “(1) that the defendant owed the

plaintiff a duty, (2) that the defendant breached that duty, (3) that the breach of

duty was the proximate cause of the plaintiff’s injury, and (4) that the plaintiff in

fact suffered injuries or damages.” Webb v. Univ. of Utah, 125 P.3d 906, 909

(Utah 2005). The district court found that M s. Tingey failed to show that

Radionics had breached any duty owed to her. Radionics contends that there is no

duty because the device was not defective. Specifically, Radionics argues that

“under Utah law a manufacturer does not have a duty to refrain from marketing a

non-defective product [even though] an alternative safer design was available.”

Aplee. Br. at 6. As we have already determined, however, M s. Tingey has

established the existence of a jury question concerning whether the device

contained a design defect that made it unreasonably dangerous. W e must

therefore reverse summary judgment on her negligence claim.

      4. Causation

      Finally, we consider whether M s. Tingey presented sufficient evidence to

survive summary judgment that the shock she received from the radiofrequency

device caused her neurogenic bladder. Such a show ing on causation is a

necessary element of each of her claims. To establish causation, M s. Tingey

                                         -24-
relied on circumstantial evidence based in part on her own testimony, and in part

on medical testimony. The district court struck her medical expert testimony

concerning causation, finding it unreliable under Fed. R. Civ. P. 56(e) and Fed. R.

Evid. 702. It then concluded that M s. Tingey had failed to present evidence to

support the causation element of her claims.

      Because medical testimony was necessary on the causation issue, the

evidentiary issues under Rule 702 are closely intertwined with the ultimate

summary judgment issue. Both federal and state law play a role in the summary

judgment determination. W hile federal law governs the issue of whether the

non-moving party in a diversity case has presented evidence sufficient to establish

a genuine issue of material fact concerning causation, see Burnette v. Dow

Chemical Co., 849 F.2d 1269, 1274 (10th Cir. 1988), “the underlying cause of

action, with its attendant elements and requirement of proof in a diversity case, is

governed by state law.” M oe v. Avions M arcel Dassault-Breguet Aviation,

727 F.2d 917, 932 (10th Cir. 1984). W e thus look to state law to determine what

theories of causation are permissible and the general means permitted to establish

causation.

      Before turning to an analysis of Utah law on the subject of proof of

causation, we will first discuss the evidence presented on the causation issue. In

addition to M s. Tingey, four doctors and two lay witnesses provided evidence on

                                        -25-
this issue. After summarizing this evidence, we will analyze it under Utah law

concerning differential diagnosis and circumstantial evidence.

             a. The evidence

                   (1.) Tingey affidavit

      M s. Tingey stated in her affidavit that prior to the procedure on M arch 10,

2000, she had never had any problems with her bladder or bowels, and had not

been diagnosed with a neurogenic bladder. During the procedure, she received a

painful shock from the device. Later that day, she began having problems

urinating normally and could not defecate. H er normal bowel function eventually

returned, but her urinary incontinence persists.

                   (2.) M edical testimony

      The medical testimony was as follow s:

                          (A) Dr. Landau

      Dr. Stuart T. Landau is a urologist, who Dr. Rosenthal asked to examine

M s. Tingey. He diagnosed M s. Tingey with a “sensory-type neurogenic bladder.”

Aplt. App., Vol. I, at 110. He stated, however, that “[w]hether this [condition] is

related to this procedure in the L5 region is impossible to know for sure.” Id.

The reason for this is that the nerve roots for the bladder are not located in the L5

region. Thus, the current would have had to move along the spinal cord to

produce M s. Tingey’s bladder injury, a possibility the likelihood of which

Dr. Landau characterized as “unknown.” Id. In a later letter to Dr. Rosenthal,

                                        -26-
Dr. Landau reiterated that he did “not have a good explanation for the bladder

situation.” Id. at 111.

                           (B) Dr. Platt

      M s. Tingey was also examined by another urologist, D r. M cKay L. Platt.

Dr. Platt stated, in a letter to M s. Tingey’s attorney:

      It is my opinion that [the] events of 13 M ay resulted in the
      neurogenic bladder. The patient’s voiding pattern before this time
      was normal and the patient had no previous urinary retention. The
      procedure done on the above date is the cause of the patient’s urinary
      retention in my opinion. I cannot even postulate any reasonable
      alternative explanation.

Id. at 127.

      Dr. Platt later reiterated this opinion in an affidavit, stating that in his

opinion, “the cause of Wendie’s neurogenic bladder was the inadvertent electrical

shock W endie received during the radiofrequency procedure on M arch 10, 2000.”

Id., Vol. II, at 451. Dr. Platt’s opinion thus supports M s. Tingey’s theory that the

procedure caused her neurogenic bladder.

                           (C) Dr. M iska

      M s. Tingey’s counsel also retained a neurologist, Dr. Robert M . M iska, to

provide an opinion concerning the cause of her injuries. His opinion, however,

proved unfavorable to her position on causation. In a letter to M s. Tingey’s

counsel, Dr. M iska stated: “I continue to have a complete lack of understanding

as to why an attempted radio frequency lesion of the L5 dorsal root ganglion

                                           -27-
should produce isolated urinary sphincter incontinence.” Id. at 540. He

continued:

      W hile I understand that there appears to be a cause and effect
      relationship between the procedure in question and the subsequent
      complaint of urinary incontinence . . . there is still a considerable
      “leap” to associate the two, especially when the recognized
      physiologic implications of dorsal rhizotomy are so benign, and there
      are no reported cases of inadvertent injury to lower sacral nerve
      roots.

Id.

      Dr. M iska stated that he could not “reasonably explain M s. Tingey’s

current difficulties on the basis of what I know.” Id. He further noted the lack of

evidence of a visible lesion through lumbar M RI scanning, but noted “it is still, of

course, possible that a very limited type of injury to the conus medullaris might

produce sphincter incontinence, though even then, some incontinence of the anal

sphincter would also be expected, and there has been none.” Id. at 541. 8

                          (D) Dr. Rosenthal

      Dr. Rosenthal was the physician who performed the procedure that

M s. Tingey believes caused her injuries. He was deposed twice in connection

with M s. Tingey’s injuries, with dramatically different results. Not surprisingly,

Radionics focuses its attention on his first deposition, which is favorable to its

8
       It is unclear whether Dr. M iska was speaking of permanent anal sphincter
incontinence, as it must be recalled that M s. Tingey did complain about transient
inability to control bowel function after the procedure, which later resolved itself.

                                         -28-
position in this case. M s. Tingey relies heavily on the view s expressed in his

second deposition.

                                   (i.) First deposition

         At the time Dr. Rosenthal gave his first deposition, as part of this federal

court action against Radionics, M s. Tingey had sued him in a separate action in

state court for medical malpractice. He was adamant during his first deposition

that the procedure he performed had not, indeed could not have, caused

M s. Tingey’s injuries.

         Dr. Rosenthal was asked, for example, about an opinion he had expressed

early on in his treatment notes. At the time, he had suggested that although he

had been using the device on the L5 nerve root, the electrical energy could have

spread to other nerves. W hen asked if he still believed in that possibility, he

replied:

                Absolutely not. [ . . . ] [L]et me say it this way. I sleep very
         well at night. I have no question in my mind that – that I did not
         damage this person in any way, and, you know, it would really bother
         me if I had. And what’s happened here unfortunately is it scared her,
         she’s angry, she’s a person who abuses medications, she’s probably
         run through a bunch of money and she wants more money.

Id. at 703 (Dep. p. 147).

         Later in the deposition, Dr. Rosenthal repeated his opinion on the causation

issue:

               And whether or not she truly does have a neurogenic bladder is
         in question, but what’s not in question is [whether] this procedure

                                           -29-
      caused it. There’s no doubt that this procedure did not cause that
      finding.

Id. at 704 (D ep. p. 149).

      Dr. Rosenthal further expressed his opinion that M s. Tingey’s symptoms

may have been caused by drug abuse, and that her desire for money to fuel her

drug addiction could explain her motivation for bringing this suit.

                                 (ii.) Second deposition

      After his first deposition, counsel for Dr. Rosenthal contacted M s. Tingey’s

counsel, stating that “D r. Rosenthal had information that would be helpful in

proving the Radionics machine was subject to a design defect, and that basically

this unfortunate event was the result of this design defect, not any fault of

Dr. Rosenthal.” Aplt. App., Vol. IV, at 972. M s. Tingey’s counsel then

suggested a second deposition of Dr. Rosenthal, to be conducted in the state case.

      Radionics was not a party to the state case against Dr. Rosenthal. It

received no notice of this second deposition, and unlike the first deposition, it did

not have a representative present. At the second deposition, Dr. Rosenthal had a

very different opinion about the causation issues than the opinion he gave at his

first deposition.

      Dr. Rosenthal began his second deposition by undermining the suggestion

that he had made in his first deposition, that chronic opiate abuse might have

caused M s. Tingey’s bladder symptoms. W hile noting that “urology is not within

                                        -30-
my specialty,” id. at 862, he suggested that the type of injury that M s. Tingey

had, a sensory neurogenic bladder, was not the kind of neurogenic bladder that

would be expected from opiate abuse. Id. at 864-65. Instead, her type of bladder

injury was more consistent with damage to the sacral nerve roots.

      At his first deposition, Dr. Rosenthal had been adamant that such damage to

the nerve roots that control bladder function could not have been caused by an

electric shock at the L5 location, where the device’s probe had been located at the

time of the alleged injury. Now, he was not so sure. He suggested that

“retrograde conduction” might explain M s. Tingey’s injuries:

      A. Okay. W hen the shock was delivered, a nerve is a conductive
      tissue, so it causes the nerve to depolarize. In other words, she got a
      shock down her leg, certainly.

      Q. Uh-huh.

      A. However, the nerve . . . when an external shock is delivered
      doesn’t know, you know, that it needs to just go down the leg. It
      also probably went up.

      Q. Okay.

      A. That’s what they call retrograde conduction. W ell, if you look,
      as the fibers travel up they become in close proximity to one another.

      Q. Uh-huh.

      A. And so it’s possible, and this is the best that I can come up with,
      that these – that this retrograde conduction caused either – probably I
      think what may have happened is that to really explain this, it
      probably went into – to the spinal cord and caused that population of
      neurons to fire.

                                         -31-
      Q. Uh-huh.

      A. And somehow that resulted – that maybe the – the thing that
      resulted in this damage.

Id. at 868-69.

      Dr. Rosenthal next considered medical evidence that seemingly posed a

challenge to his theory. An electromyelogram (EM G) performed by a neurologist

had failed to reveal any damage to M s. Tingey’s sacral nerve roots. He explained

the lack of evident damage as follow s:

      A. And the answer is that EM G – there’s four fiber types . . . .
      [T]wo of them are covered with this myelin sheath, and those are the
      types that EM G is able to detect. The smaller fiber types, A delta
      and C fibers, and EM G is not able to – to detect or sense damage to
      those fibers. W ell, it turns out that those are the fiber types that go
      to the bladder.

Id. at 869. Dr. Rosenthal also stated that nerves without myelin sheathing, such

as those running to the bladder, are more vulnerable to electric shock, though he

did not know why. 9

      Counsel then asked him a key question:

      Q. Okay. Based upon all you now know and what you studied, do
      you have an opinion as to . . . more probably than not what caused
      her neurogenic bladder?

      A. This has been a difficult case because it’s very hard to come to,
      you know, to come to a conclusion.

9
       M yelin is a form of fatty sheath that surrounds and protects certain nerve
fibers. Aplt. App., Vol. IV, at 869.

                                          -32-
       Q. Uh-huh.

       A. But after doing some further studying and looking at the chart
       again and comparing what I learned in this studying to D r. Landau’s
       report, I would have to conclude that the – the procedure that I
       performed did have a – was the cause of her – of her bladder
       problem.

Id. at 875.

       Perhaps the most difficult statement from Dr. Rosenthal’s first deposition

for his new theory lay in his previous deposition testimony that a mere seven-volt

shock could not have produced M s. Tingey’s injuries. W hen asked about this at

his second deposition, Dr. Rosenthal explained that in the stim mode, the radio

frequency current oscillates very quickly. Id. at 885.

                    (3.) O ther testimony concerning causation

       In addition to M s. Tingey’s testimony and that of various physicians, there

was testimony from two engineers familiar w ith the device who had worked with

Radionics. Ray Fredricks testified that Radionics had never had a complaint

about the toggle switch. Id., Vol. III, at 785. He also stated that a mere seven

volts could not lesion nerves; it w ould merely cause discomfort. Id., Vol. II, at

523. Gerald Gagon testified that M s. Tingey was the only patient he had ever

heard of being shocked as a result of activation of the toggle switch. Id. at 530.

He was aware of no injuries from the device in stim mode. Id. at 539.

                                        -33-
              b. Application of causation test to the evidence

        M s. Tingey argues that causation may be proved by circumstantial

evidence; that is, that an inference of causation may be drawn based on “the

strong temporal relationship between the shock and the immediate onset of

W endie’s injury.” Aplt. Opening Br. at 30, 33. The Utah courts have recognized

that a temporal relationship between exposure to a hazardous substance and injury

can provide circumstantial evidence of causation. Alder v. Bayer Corp., 61 P.3d

1068, 1085-90 (Utah 2002). 10    W here the cause of an injury is obvious (for

example, where a cyclist breaks his arm in a fall), the sequence of condition

followed by event followed by altered condition may by itself provide sufficient

evidence of causation. Id. at 1090. W here causation would not be obvious to an

unaided finder of fact, however, plaintiff must also present some documented

proof or expert medical testimony that exposure to the harmful substance could

have been a cause of the type of injury that plaintiff received. See id. at 1087,

1089.

        The primary difficulties with causation under the facts of this case are that

the voltage was administered to M s. Tingey’s sacral nerves, not those going to the

bladder, and that only seven volts or so of electricity was applied by the shock.

10
      Although Alder concerned hazardous chemical fumes, the same sort of
analysis has been applied where a plaintiff alleges permanent physical injury due
to shocks received from ambient electricity. See Easum v. M iller, 92 P.3d 794,
801-04 (W yo. 2004).

                                          -34-
Adler, however, does not require a plaintiff to provide direct proof through

medical studies of the mechanism of the illness or to quantify the harmful

exposure necessary to have produced the harm alleged by the plaintiff. Instead, a

plaintiff may establish causation circumstantially through the use of differential

diagnosis. Quoting language in Zuchowicz v. United States, 140 F.3d 381 (2d Cir.

1998) that it called “a thoughtful review of the theory of causation,” the Alder

court explained that

      [I]t is well established that causation “may be proved by
      circumstantial evidence,” . . . and that “[t]he causal relation between
      an injury and its later physical effects may be established by the
      direct opinion of a physician, by his deduction by the process of
      eliminating causes other than the traumatic agency, or by his opinion
      based upon a hypothetical question.

Alder, 61 P.3d at 1090 (quoting Zuchowitz, 140 F.3d at 389) (further quotation

omitted).

                   (1.) G eneral principles

      Alder involved hospital employees w ho asserted that an improperly

installed, poorly ventilated x-ray processing machine caused them various

illnesses, including fibromyalgia and chronic fatigue syndrome. The

manufacturer argued on appeal that “there must be a basis for generally ‘ruling in’

an agent as a known cause of the relevant class of injury before admitting

differential diagnosis expert testimony.” Alder, 61 P.3d at 1084. The Utah

Supreme Court did not disagree with this analysis. It observed, however, that

                                        -35-
“[t]he record in the instant case . . . contains ample documentation that exposure

to x-ray processing chemicals causes the types of harm alleged by [plaintiffs].”

Id. The absence of quantitative laboratory-based testing would not, therefore,

vitiate the proof offered by differential diagnosis, “one of the oldest and most

widely used and recognized of all the methods.” Id.

         M s. Tingey primarily relies on differential diagnosis to establish causation.

“Differential diagnosis . . . is a standard scientific technique of identifying the

cause of a medical problem by eliminating the likely causes until the most

probable one is isolated.” Westberry v. Gislaved Gumm i AB, 178 F.3d 257, 262

(4th Cir. 1999). “In performing a differential diagnosis, a physician begins by

‘ruling in’ all scientifically plausible causes of the plaintiff’s injury. The

physician then ‘rules out’ the least plausible causes of injury until the most likely

cause remains.” Glastetter v. Novartis Pharm. Corp., 252 F.3d 986, 989 (8th Cir.

2001).

         Radionics asserts that there are two problems with M s. Tingey’s use of

differential diagnosis, given the facts of this case. First, her evidence fails to

“rule in” the shock she received as a known cause of her injuries. Second, she

fails to “rule out” other possible causes. As both requirements in fact were met,

we conclude that summary judgment was inappropriate on the causation issue.

                                           -36-
                      (2.) Application to evidence

                            (A.) Dr. Rosenthal

      The district court struck Dr. Rosenthal’s second deposition, for two

independent reasons. First, M s. Tingey failed to provide notice of the deposition,

which was taken in a separate state proceeding, to Radionics. Second, it found

that D r. Rosenthal’s opinion was not reliable.

      Concerning the first reason, the district court stated that “[u]nder Rule 32

of the Federal Rules of Civil Procedure, the deposition cannot be used against

Defendant in this case as Defendant had no notice of the deposition and as a

result was not afforded the opportunity to be present at the deposition and [to]

cross-examine the witness.” Id., Vol. IV, at 1013. Rule 32(a) states that a

deposition “may be used against any party who was present or represented at the

taking of the deposition or who had reasonable notice thereof.” As the case law

reveals, the rule is primarily applied as a limitation on introducing deposition

testimony at trial.   W hile a few courts have applied Rule 32(a) to deposition

testimony introduced in summary judgment proceedings, see, e.g., Nippon Credit

Bank, Ltd. v. M atthews, 291 F.3d 738, 750-51 (11th Cir. 2002), in our view this

application represents an overly-expansive view of the Rule, given the purpose of

the rule and the mechanics of summary judgment procedure.

      Parties may file affidavits in support of summary judgment without

providing notice or an opportunity to cross-examine the affiant. See Fed. R. Civ.

                                         -37-
P. 56(c). The “remedy” for this non-confronted affidavit testimony is to file an

opposing affidavit, not to complain that one was not present and permitted to

cross-examine when the affidavit was signed. For this reason, the Ninth Circuit

has permitted a party to introduce deposition testimony for summary judgment

purposes against a party who was not present at the deposition, by construing the

deposition as an affidavit. Hoover v. Switlik Parachute Co., 663 F.2d 964,

966-67 (9th Cir. 1981). A similar reasoning applies here. If Radionics wished to

controvert Dr. Rosenthal’s testimony for summary judgment purposes, it could

either have noticed an additional deposition of Dr. Rosenthal, or presented

additional testimony from its own expert to cast doubt on his conclusions. 11

Therefore, the district court should not have struck Dr. Rosenthal’s deposition

under Rule 32(a).

      Alternatively, the district court found the testimony contained in

Dr. Rosenthal’s second deposition unreliable and therefore inadmissible, stating:

      Plaintiff failed to demonstrate that Dr. Rosenthal is qualified to
      determine issues of causation in this matter and by Dr. Rosenthal’s
      own admission he is not. The Court finds that the materials
      Dr. Rosenthal testified he review ed prior to stating his opinion did
      not support Dr. Rosenthal’s opinion on causation. The Court further
      finds that there is nothing in the record to demonstrate that
      Dr. Rosenthal’s theory of causation is reliable and that
      Dr. Rosenthal’s own testimony shows that his new explanation about
      how the injury might or could have occurred is mere supposition.

11
      W e express no opinion concerning the use of either of D r. Rosenthal’s
depositions in a trial of this case.

                                        -38-
      W hile the Court acknowledges that causation can be established in
      some cases through a differential diagnosis, Dr. Rosenthal failed to
      adequately address any of the other possible causes of the injury and
      also failed to “rule in” the surgical procedure at issue in this case as
      a potential known cause.

Aplt. App., Vol. IV, at 1014.

      Federal Rule of Evidence 702 provides that

      [i]f scientific, technical, or other specialized knowledge will assist
      the trier of fact to understand the evidence or to determine a fact in
      issue, a w itness qualified as an expert by knowledge, skill,
      experience, training, or education, may testify thereto in the form of
      an opinion or otherw ise.

      In Daubert v. M errell Dow Pharmaceuticals, Inc., 509 U.S. 579, 589-90

(1993), the Supreme Court made it clear that the touchstone of admissibility

under R ule 702 is whether the scientific evidence presented is reliable.

Specifically, “[u]nder Rule 702, expert testimony is admissible if it will assist the

trier of fact and if (1) the testimony is based upon sufficient facts or data, (2) the

testimony is the product of reliable principles and methods, and (3) the w itness

has applied the principles and methods reliably to the facts of the case.” Lantec,

Inc. v. Novell, Inc., 306 F.3d 1003, 1024 (10th Cir. 2002) (quotation omitted).

This court may only reverse the district court’s application of the Daubert

standards for an abuse of discretion. Lantec, 306 F.3d at 1024. This means that

“[w]e will not . . . disturb a district court’s ruling absent our conviction that it is

arbitrary, capricious, whimsical, manifestly unreasonable, or clearly erroneous.”

                                           -39-
Bitler v. A.O. Smith Corp., 400 F.3d 1227, 1232 (10th Cir. 2004), cert. denied,

126 S.Ct. 395 (2005).

      W e will consider each of the reasons given by the district court for

excluding Dr. Rosenthal’s testimony:

      (1) Dr. Rosenthal’s qualifications to determine issues of causation

      The district court concluded that M s. Tingey had failed to demonstrate that

Dr. Rosenthal was qualified to determine issues of causation. Dr. Rosenthal

admitted that he was not a urologist. Aplt. App., Vol. IV, at 862. He relied,

however, on his general training and experience as well as his study of published

authorities dealing with the specific issues presented in this case. Dr. Rosenthal

studied several texts concerning types of neurogenic bladder problems and nerve

damage. Id. at 862-65. He also correlated his research to clinical findings made

by other doctors who had examined M s. Tingey. Id. at 865-68. He adequately

demonstrated his qualifications to express an opinion on causation in this matter,

and the district court abused its discretion in concluding to the contrary.

      (2) Dr. Rosenthal’s use of supporting materials

      The district court found that the materials on which Dr. Rosenthal relied

did not support his opinion on causation. Dr. Rosenthal testified that he reviewed

two medical treatises, primarily in an effort to rule out drug abuse as a cause for

M r. Tingey’s bladder dysfunction. His review of these materials convinced him

that M s. Tingey’s bladder problems had resulted from a traumatic injury to her

                                         -40-
sacral nerve roots, rather than her abuse of opiates. His description of these

materials does appear to support his theory of causation.

      Dr. Rosenthal also reviewed Dr. Landau’s report, which he concluded

further supported his conclusion that M s. Tingey’s injury resulted from sacral

nerve root damage. W hile Dr. M iska’s report tended to contradict

Dr. Rosenthal’s impression concerning traumatic nerve damage, because his

electromyography (EM G) did not uncover any evidence of acute or chronic

denervation changes of the L5 nerve, and no evidence of damage to the S1 nerves

on either side, Dr. Rosenthal did not believe that this ruled out his theory of

causation. Rather, he explained that the EM G would not detect damage to small

nerve fibers of the type that go to the bladder. These non-myelinated nerve fibers

would also be more vulnerable to damage from an electric shock. Thus, the

materials from M s. Tingey’s other doctors, which Dr. Rosenthal reviewed, did not

contradict his theory of causation.

      Dr. Rosenthal also stated that he was unaware of any report in the medical

literature that identified bladder nerve damage as a possible consequence of the

lesioning procedure. He did not rely on this medical literature, however, as a

basis for his opinion. W e conclude that the district court erred in concluding that

the materials on which Dr. Rosenthal relied did not support his theory of

causation.

      (3) Lack of record evidence for Dr. Rosenthal’s theory of causation

                                         -41-
      The district court also stated that there was nothing in the record to

demonstrate that Dr. Rosenthal’s theory of causation was reliable. The district

court appears to have relied on lack of corroboration, beyond Dr. Rosenthal’s ow n

testimony. As we have already pointed out, however, in reaching his conclusions

regarding causation, Dr. Rosenthal relied on treatises, medical tests and

laboratory findings. M oreover, “disputes as to the strength of his credentials,

faults in his use of differential etiology as a methodology, or lack of textual

authority for his opinion, go to the weight, not the admissibility of his testimony.”

Zuchowicz, 140 F.3d at 387 (quotation omitted).

      (4) Speculative nature of D r. Rosenthal’s causation theory

      The district court opined that “Dr. Rosenthal’s own testimony shows that

his new explanation about how the injury might or could have occurred is mere

supposition.” A plt. App., Vol. IV, at 1014. The court did not refer to specific

examples in the summary judgment record to support its conclusion, but our

review of the record convinces us that whatever the ultimate merit of

Dr. Rosenthal’s opinion, it is not based on mere supposition. W hile

Dr. Rosenthal did use such phrases as “here’s how I might explain it,” id. at 868,

or “what seems to have happened,” id., he ultimately provided a scientific basis to

describe the mechanism of M s. Tingey’s injury.

      Specifically, Dr. Rosenthal testified that (1) M s. Tingey has a hypotonic

bladder, consistent with an injury to the sacral nerve roots; (2) during the

                                         -42-
procedure, a shock was delivered to her L5 nerve, near the dorsal root ganglion;

(3) the shock probably caused retrograde conduction through the spinal cord

causing damage to the sacral nerve roots; and (4) this damage was not visible on

an EM G because the nerves damaged were small, unmyelinated nerves leading to

the bladder, which are more vulnerable to electric shock. This theory represents

more than mere supposition, and the district court erred in excluding it for that

reason.

      (5) Dr. Rosenthal’s use of differential diagnosis

      The district court concluded that “D r. Rosenthal failed to adequately

address any of the other possible causes of the injury and also failed to ‘rule in’

the surgical procedure at issue in this case as a potential known cause.” Id. at

1014. This conclusion is incorrect. A careful review of D r. Rosenthal’s

deposition testimony shows that he took great pains to show that M s. Tingey’s

injuries were inconsistent with opiate abuse, the only other possible cause

discussed in any detail in the record. Also, as we have discussed, his testimony

provided a detailed mechanism to “rule in” the procedure as a cause of the injury.

Any doubts about the validity of his theory, as we have emphasized, go to the

weight, rather than the admissibility, of Dr. Rosenthal’s testimony.

                             (B.) Dr. Platt

          The district court struck Dr. Platt’s affidavit, finding it “so lacking in

foundation and therefore unreliable that it does not meet the requirements of

                                              -43-
Rule 56(e) of the Federal Rules of Civil Procedure or Rule 702 of the Federal

Rules of Evidence.” Id., Vol. IV, at 1013. The district court gave three reasons

for rejecting Dr. Platt’s affidavit. First, “[t]he Affidavit does not contain specific

facts to support a direct or circumstantial case of causation.” Id., Vol. IV at 1013.

The affidavit does, however, contain specific facts describing the nature of

M s. Tingey’s injuries and detailing a circumstantial case for causation.

Specifically, Dr. Platt stated that: (1) he had conducted an examination of

M s. Tingey’s medical records and had found no evidence in these records prior to

M arch 10, 2000, that M s. Tingey had experienced any bladder problems; (2) her

complaints of bowel and bladder incontinence had begun after she underwent a

radiofrequency surgical procedure on M arch 10, 2000 at Orem Community

Hospital; (3) he conducted a bulbocavernous reflux test on M s. Tingey with

negative results, from which he determined that the nerves going to her bladder

had been damaged; (4) she continues to suffer from a mixed sensory and

neurogenic bladder dysfunction; and (5) in his opinion, “the cause of

[M s. Tingey’s] neurogenic bladder was the inadvertent electrical shock [she]

received during the radiofrequency procedure on M arch 10, 2000.” Id., Vol. II, at

451. W e conclude that the district court abused its discretion in determining that

the affidavit contained insufficient facts to establish causation.

      Second, the district court stated that the affidavit was deficient because it

did not set forth that Dr. Platt had “the necessary qualifications to opine on how

                                         -44-
injury could have occurred to Plaintiff or rule out other possible causes for

Plaintiff’s alleged injuries.” Id., Vol. IV, at 1013. Various exhibits were attached

to the affidavit, including letters on Dr. Platt’s letterhead stationery, where he is

identified as a Diplomate of the American Board of Urology. Id., Vol. II, at 452.

Other exhibits detailed the medical tests Dr. Platt performed on M s. Tingey, and

the conclusions he drew from the test results, particularly in light of his

experience with other patients. This is clearly a case where “the doctor’s training

and experience placed his report and testimony well above the Rule 702/Daubert

bar.” Feliciano-Hill v. Principi, 439 F.3d 18, 25 (1st Cir. 2006); see also Bitler,

400 F.3d at 1237 (“In the medical context, differential diagnosis is a common

method of analysis, and federal courts have regularly found it reliable under

Daubert.”).

      Finally, the district court found Dr. Platt’s affidavit deficient because it did

not discuss the evidence from Dr. M iska, a neurologist who found no evidence

that M s. Tingey had incurred nerve damage. Dr. Platt specifically found, from a

urological standpoint, that “the nerves going [M s. Tingey’s] bladder have been

damaged.” Aplt. App., Vol. II, at 450. Dr. M iska stated that the neurological

tests he performed had not revealed nerve damage. See id. at 540. The apparent

disagreement between these two physicians, however, goes to the weight and not

the admissibility of Dr. Platt’s opinion. See Feliciano-Hill, 439 F.3d at 25

(holding that “[t]he mere fact that two experts disagree is not grounds for

                                          -45-
excluding one’s testimony.”). Dr. Platt’s failure to refute, or even to discuss,

Dr. M iska’s opinion does not make his opinion inadmissible under Rule 702 or

Daubert.

      Radionics further argues that the procedure itself, rather than the shock,

could have been the cause of M s. Tingey’s injuries. Radionics did not present

expert testimony to substantiate a theory that the procedure itself caused the

injuries, nor did it develop a legal argument that expert testimony is not necessary

to factor in the pre-shock lesioning as a potential cause necessary for

consideration in a differential diagnosis analysis. As a consequence, for purposes

of this appeal we deem the absence of such expert testimony fatal to Radionics’

position.

      W e conclude that the district court erred in striking Dr. Rosenthal’s second

deposition and in excluding Dr. Platt’s affidavit. W ith these two items of

evidence included, M s. Tingey has made a sufficient showing on the causation

issue to survive summary judgment on her claims.

      5. M s. Tingey’s cross-motion for summary judgment

      M s. Tingey also appeals from the district court’s denial of her motion for

summary judgment. In her motion, she requested summary judgment on the

follow ing issues: (1) that the Radionics device was unreasonably dangerous as a

matter of law; (2) that its defect existed at the time the device left Radionics’

control; (3) that the defect in the device caused her neurogenic bladder injury;

                                         -46-
(4) that an alternative, safer design was available at the time Radionics placed the

device into the stream of commerce; and (5) that Radionics failed to w arn users

and consumers about the hidden dangers posed by the device’s toggle switch. As

our foregoing analysis makes clear, while Radionics is not entitled to summary

judgment on these issues, neither is M s. Tingey. Genuine issues of fact remain as

to each of the listed issues, precluding the entry of summary judgment in favor of

either party. W e therefore affirm the district court’s denial of M s. Tingey’s

motion for summary judgment.

                                   C ON CLU SIO N

      W e AFFIRM the order of the district court denying M s. Tingey’s motion

for summary judgment. W e REVERSE the district court’s order granting

summary judgment to Radionics, striking the affidavit of M s. Tingey’s expert

witness, and striking the second deposition of her physician Dr. Rosenthal, and

we REM AND for further proceedings.

                                                     Entered for the Court

                                                     Paul J. Kelly, Jr.
                                                     Circuit Judge

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