                                PUBLISHED

                  UNITED STATES COURT OF APPEALS
                      FOR THE FOURTH CIRCUIT


                               No. 15-1950


HOWARD E. NEASE; NANCY NEASE,

                Plaintiffs – Appellees,

           v.

FORD MOTOR COMPANY, a Delaware Corporation,

                Defendant – Appellant.



Appeal from the United States District Court for the Southern
District of West Virginia, at Huntington.  Robert C. Chambers,
Chief District Judge. (3:13-cv-29840)


Argued:   September 21, 2016                 Decided:   February 1, 2017


Before MOTZ, TRAXLER, and AGEE, Circuit Judges.


Reversed and remanded with instructions by published opinion.
Judge Traxler wrote the opinion, in which Judge Motz and Judge
Agee joined.


ARGUED: Jonathan D. Hacker, O’MELVENY & MYERS LLP, Washington,
D.C., for Appellant.    Larry Lee Javins, II, BAILEY, JAVINS &
CARTER, L.C., Charleston, West Virginia, for Appellees.      ON
BRIEF: Andrew B. Cooke, FLAHERTY, SENSABAUGH & BONASSO, PLLC,
Charleston, West Virginia; Bradley N. Garcia, O’MELVENY & MYERS
LLP, Washington, D.C., for Appellant.     Tony L. O’Dell, TIANO
O’DELL, PLLC, Charleston, West Virginia, for Appellees.
TRAXLER, Circuit Judge:

       Howard    and    Nancy    Nease     commenced     this      product     liability

action against Ford Motor Company, alleging that Howard suffered

serious injuries in an accident caused by a design defect in the

speed control system of his 2001 Ford Ranger pickup truck.                            Over

Ford’s objection, the Neases offered the expert testimony of

Samuel Sero that the speed control cable in the 2001 Ranger is

susceptible to getting stuck or “bound” while the throttle to

which it is linked is in the open position, thus preventing the

driver from slowing down the vehicle.                        The Neases claim that

this is precisely what happened while Howard was driving his

2001    Ranger.          A    West    Virginia        jury    awarded       the      Neases

$3,012,828.35 in damages.             Ford made several post-trial motions,

including a motion for judgment as a matter of law under Rule

50(b) of the Federal Rules of Civil Procedure.                         In its motion,

Ford renewed its pre-trial argument that Sero’s testimony was

inadmissible under Daubert v. Merrell Dow Pharmaceuticals, Inc.,

509 U.S. 579 (1993), and should have been excluded.                                 In the

alternative,      Ford       sought   a   new   trial    on    the    basis    that     the

district    court       erroneously        instructed        the     jury     on    strict

liability       under    West    Virginia       law   and     erroneously          admitted

evidence of prior incidents involving Ford vehicles.

       The district court denied Ford’s post-trial motions.                           Ford

now appeals.           For the reasons that follow, we conclude that

                                            2
Sero’s testimony should not have been admitted.                                    And, without

any    other      expert   testimony       to     establish         that       the       2001    Ford

Ranger      was    defectively       designed       and    that          there       were       safer

alternative         designs       available        that        a     reasonably             prudent

manufacturer would have adopted, the Neases cannot prove their

case under West Virginia law.                   Accordingly, we must reverse and

remand for entry of judgment in Ford’s favor.

                                             I.

       On   November       20,    2012,     Howard      was        driving         his    recently

purchased, used 2001 Ford Ranger pickup truck on U.S. Route 60

in    St.   Albans,    West       Virginia.        According            to    Howard,       he    was

traveling 45-50 mph when he discovered his vehicle would not

slow down when he released the accelerator pedal.                                    He tried to

slow the pickup truck by applying the brakes, but to no avail.

In order to avoid running into pedestrians or other cars, Howard

turned the Ranger off the road, drove over a curb, and crashed

into a brick car wash building.                    For about 25-30 seconds after

the    pickup      truck    hit    the    brick     wall,          the       tires    reportedly

continued spinning until the engine shut down.                                Howard’s Ranger

had    approximately        116,000       miles    on     it       at    the       time     of    the

accident, and there is no indication in the record that the

vehicle      had    ever    manifested        problems         with          the   accelerator,

cruise control or throttle.                 The Neases thereafter filed this

action      against        Ford     Motor       Company,           alleging          that        Ford

                                              3
defectively designed the accelerator pedal-to-throttle assembly

of the 2001 Ranger pickup truck.                The complaint asserted causes

of   action     for   strict    liability,       negligence,     and    breach     of

warranty.

                                         A.

     The general design and function of the throttle control

system    in    the   2001     Ford    Ranger    is    typical   of    any    modern

passenger      vehicle.        The     driver    controls    engine     speed      by

depressing      the   accelerator       pedal,     which    is   linked      to   the

throttle, which, in turn, regulates the amount of air flowing

into the engine.        When the accelerator pedal is depressed, the

throttle opens and engine speed increases; when the accelerator

pedal is released, the throttle closes, airflow is restricted

and engine speed decreases.

     In the 2001 Ford Ranger, the accelerator pedal is linked to

the throttle body by a steel accelerator cable.                  The accelerator

cable is attached to a lever on the throttle body; the lever

operates the throttle valve and the throttle valve controls the

engine’s air intake.           As “the accelerator pedal is depressed,

the accelerator cable [which is attached to the throttle lever]

is pulled to open the throttle [valve] and increase the engine

speed.”        J.A.   83.      In    essence,    the   accelerator     pedal,     the

accelerator cable and the throttle lever form a pulley system

that opens the throttle.               As a safety feature, the throttle

                                          4
lever is equipped with return springs that exert 7.2 pounds of

continuous force to pull the throttle closed when the driver

takes his foot off of the accelerator.

       In addition to the accelerator pedal-to-throttle assembly,

another means by which the driver of a 2001 Ranger can open the

throttle is the cruise control system.               This system is operated

by a “speed control actuator and [a] speed control cable.”                   J.A.

85.     The cruise control system incorporates an electric motor

that operates a steel cable—the speed control cable—to open and

close the throttle.          The speed control cable and the accelerator

cable are attached to the same throttle lever/pulley system that

operates the throttle valve.           When the speed control actuator

receives input from the cruise control switch on the steering

column, the motor manipulates the speed control cable to pull

the throttle lever independently of the main accelerator cable.

       The throttle control design takes into account that both

cables are attached to the same throttle lever/pulley-system.

In    order   to   prevent    significant   stress    to   the   speed    control

cable that could potentially occur when the cruise control is

not engaged and the throttle lever is being controlled by the

accelerator pedal and cable, Ford incorporated a “‘lost motion’

configuration” for the speed control cable assembly.                     J.A. 85.

In this design, the steel speed control cable runs from the

motor in the speed control actuator through a plastic “guide

                                       5
tube,”      and   is    attached        to     the   throttle    lever    by    a    plastic

“connector.”           Id.     The connector and the guide tube move with

the throttle lever when it is being operated by the accelerator

cable.       The speed control cable itself stays stationary while

the guide tube moves up and down the cable and in and out of a

stationary plastic casing tube, called a “casing cap,” which is

attached to the motor.                  Id.     The gap between the moving guide

tube and the stationary casing cap is approximately 0.04 inches.

                                                B.

      Following the accident, plaintiffs hired Samuel Sero, an

electrical        engineer,        to   examine      the   engine   and   the       throttle

assembly     in    Howard’s        2001       Ford   Ranger.     Sero    approached       his

examination with the view that in failure-to-decelerate cases,

the issue is often one of “mechanical binding” and that a post-

accident investigation should “look at the accelerator cable,

[to] see if there’s anything on it that bound up and prevented

it   from    closing         the   throttle      when   the    accelerator      pedal     was

released, looking for . . . any kind of grime, grit, or anything

that could bind that one.”                     J.A. 613. 1      Sero indicated that a

post-accident          investigation           should      therefore     look       for   the

      1Contaminants that typically build up on automobile engine
parts over time include carbon, substances accumulating from
“vapors off of gasoline, brake fluid, hydraulic fluids, battery
acids, steel, copper, aluminum, [and] magnesium,” J.A. 644, as
well as the dirt and grime that washes up into the engine from
the surface of the road.


                                                 6
presence of contaminants and particles that could lodge between

the speed control guide tube and the casing cap and create a

“wedging effect.”           J.A. 628.        Sero used a borescope to inspect

the speed control assembly.

       A borescope is essentially a fiber-optic tube equipped with

a    light   that    a     mechanic     or   an    engineer      can   insert    into   an

inaccessible        area    of    the   engine      and   view    a    given    component

without having to disassemble the engine.                     When he examined the

speed control cable in the Neases’ pickup, Sero did not find any

materials wedged between the guide tube and the cap.                            In fact,

he     noted    that        the    speed      control      cable        moved    freely.

Nevertheless, Sero concluded that contaminants had entered and

built up in the casing cap over time, causing the guide tube to

stick and, therefore, the throttle plate to remain open.                            Sero

testified that he was able to identify “a lot of contaminant . .

. deposited” in the casing cap, J.A. 636, and “along the guide

tube,” J.A. 631.            Sero also noticed “gouges or striations” on

the guide tube.          J.A. 645.      From this observation, Sero believed

that there had been “a rough, abrasive material between the . .

. interior of the [casing] cap tube and the surface of the guide

tube,” indicative of binding.                     J.A. 645.       Sero surmised that

sufficient debris had accumulated to create the “wedging effect”

needed to keep the throttle open after the accelerator pedal was

released.      However, Sero had no way of knowing precisely how

                                             7
much contaminant was present in the casing cap or whether it was

enough to lodge in the 0.04 inch-gap between the cap and the

guide tube such that the throttle would be stuck in the open

position.    The borescope is simply a viewing tool; it does not

afford a means for determining the amount of the contaminant

that can be seen with the device.

     To bolster his opinion, Sero pointed to a document Ford had

prepared    in    1987    identifying        potential    risks    Ford     engineers

should consider addressing in the design of particular vehicles

in the future.           This document is called a Failure Mode and

Effects    Analysis      (“FMEA”).         According     to   Ford’s      “Potential

Failure Mode and Effects Analysis” Handbook, “[a]n FMEA can be

described as a systemized group of activities intended to: (a)

recognize        and     evaluate        the     potential        failure        of    a

product/process        and    its   effects,     (b)    identify    actions       which

could eliminate or reduce the chance of the potential failure

occurring,    and      (c)    document     the   process.”        J.A.    968.        The

primary    purposes      of   an    FMEA   include     “identify[ing]       potential

failure modes and rat[ing] the severity of their effects” and

“help[ing] engineers focus on eliminating product and process

concerns and help[ing] prevent problems from occurring.”                              Id.

An FMEA “is meant to be a ‘before-the-event’ action, not an

‘after-the-fact’ exercise.”            Id.



                                             8
      Sero testified that the 1987 FMEA “directly addresse[d] the

fact [that] dirt, grease or ice has formed between cable and

cable sheath” and therefore demonstrated that “Ford [was] well

aware of the problem of binding in the lost motion device/cruise

cable.”      J.A. 52.   Sero asserted therefore that the 1987 FMEA

proved the speed control assembly in the 2001 Ford Ranger was

susceptible to binding.        Sero was apparently unaware, however,

that the 1987 FMEA did not even apply to the 2001 Ford Ranger.

The   1987    FMEA   “dealt   with   a       vacuum-actuated    speed   control

system” that was not present in the 2001 Ranger.               J.A. 1260.

      Based on his borescope exam and the 1987 FMEA, Sero opined

that the 2001 Ford Ranger’s design was not reasonably safe and

that there were several alternative designs that Ford could have

utilized in the design of the speed control assembly:

           It is my opinion, . . . within a                    reasonable
      degree of engineering certainty that . . .

           1. Mr. Nease’s 2001 Ranger experienced a failure
      to decelerate by reason of the binding of the lost
      motion portion of the cruise . . . cable while the
      throttle was substantially open;

           2.   The cable design employed by Ford in the
      subject 2001 Ranger permits dirt, grease and grime to
      enter the conduit through which the cable passes and
      is known to cause sticking or binding of the cable;

             3.   The subject cable is defectively designed;

           4. The binding of the cable . . . was caused by
      particles of dirt and/or debris typically found under
      the hood of motor vehicles;


                                         9
           5.   The open-throttle condition . . . almost
      immediately deplete[d] the vacuum assist to the
      brakes;

           6.    The open-throttle condition, accompanied by
      loss of vacuum assist, required the application of
      brake pedal forces beyond the physical capabilities of
      Mr. Nease;

           7. The binding of the defectively-designed cable
      was the proximate cause of the crash of the Nease
      vehicle;

           8.    Safer, feasible alternative designs were
      available and known to Ford Motor Company at the time
      the 2001 Ranger was manufactured.

J.A. 53-54.

      Prior to trial, Ford moved to exclude Sero’s opinions under

Daubert on the grounds that Sero’s opinions were not based on

any   reliable   methodology      and   that      Sero   had   not   established

through testing or other means, such as scientific literature,

that the binding of the speed control assembly could actually

occur.    See    Daubert,   509    U.S.      at   597    (explaining   that   the

district court must “ensur[e] that an expert’s testimony . . .

rests on a reliable foundation” (emphasis added)).                     Ford also

argued that Sero, as an electrical engineer, was unqualified to

render an expert opinion on matters of automotive design.                     The

district court denied Ford’s motion to exclude Sero’s testimony,

concluding that Sero was sufficiently qualified by means of his

experience “design[ing] and operat[ing] . . . mechanical systems

in a variety of settings.”        J.A. 525.        The court also determined


                                        10
that    in    arriving    at     his       opinion,       Sero     employed      “standard

engineering methodology to conduct his physical inspection and

reach his opinions.”           Id.     This methodology included “physically

inspecting      the    vehicle’s       parts,          understanding      how    they      are

designed to operate, observing evidence of whether some material

interfered with the operation of the cable, and opining how that

could and did occur here.”             Id. at 526.

       The case proceeded to trial and Sero offered his opinions.

Ford attacked Sero’s opinions on cross examination and offered

its    own    expert    testimony.          Sero        acknowledged      that      when    he

performed      his    inspection      of    the        speed   control    cable      in    the

Neases’ Ranger, he did not find any materials actually wedged

between the guide tube and cap, and he noted that the speed

control cable moved freely.                Sero further admitted that he had

never actually found a bound speed cable assembly in any vehicle

that he had inspected.

       In contrast to Sero’s professed inability to determine how

much debris was present in the casing cap (because the borescope

does    not    provide     a    way        to        determine     the   scale      of     the

contaminants),        Ford’s   experts          performed        tests   on   the   Neases’

vehicle and were able to quantify the size of the contaminants

found on the Ranger’s guide tube.                     Dr. Steven MacLean, an expert

in the field of mechanical engineering, used a scanning electron

microscope to determine that “the thickest region . . . [found]

                                                11
on Mr. Nease’s guide tube . . . was approximately 50 microns in

thickness,” J.A. 2438.         For perspective, Dr. MacLean explained

that a piece of paper is about 60 microns thick, making it 10

microns thicker than the contaminants found on the guide tube in

the speed control assembly.          Either one is far smaller than the

.04 inch gap between the casing cap and guide tube.                      And, with

respect to the gouge marks Sero noticed during the borescope

exam that he believed were indicative of binding, Dr. MacLean

testified that his analysis indicated that these marks “are from

the manufacturing process, the molding process of these parts,”

not “a binding event.”        J.A. 2419.

      Sero   agreed    that   he   had   never      conducted     any   testing    to

determine whether enough debris could accumulate in the casing

cap during normal operation to resist the 7.2 pounds of force

exerted by the return spring and to cause the throttle to stick

open.    Sero    simply    relied    upon     his    observations       during    the

borescope exam, which was videotaped.                 At trial, however, Sero

was   unable    to    distinguish    between        the   video    of   the   Nease

borescope and a borescope exam for a previous case in which Sero

had testified that the speed control cable did not bind.                           He

could not tell the borescope of the cable that he said did bind

from the borescope of the cable that he said did not bind.                         In

other words, he could not tell one from the other.



                                         12
       With regard to the FMEA process that was so central to

Sero’s opinion, Ford presented evidence that potential failure

modes    identified        in    the     FMEA   had      not   occurred    during      actual

vehicle operation.              For example, Dr. MacLean explained that a

FMEA    is   a    common       “engineering       tool,”       J.A.   2475,     used   before

marketing a new product to the public to “proactively try to

determine what are all of the possible failure modes for that

particular new design.”                Id.      According to MacLean, an FMEA is

not a record of existing problems but rather “a forward-looking

tool for . . . a new product.”                        J.A. 2481.        When an FMEA is

performed,        the     manufacturer          “bring[s]       in     design    engineers,

analysis     engineers,          manufacturing           engineers,     people    from    all

different disciplines, and . . . [the group tries] to come up

with a very comprehensive and exhaustive list of failure modes.

. . . [and seek to determine] how likely it is to occur, and

what does my system do to possibly detect it and prevent it from

happening.”             J.A.     2475.         Similarly,       Karl     Stopschinski,      a

registered professional engineer and member of the Society of

Automotive Engineers, testified that the FMEA process is akin to

a   “brainstorming         session”       to    “identify       any    potential       failure

modes.”          J.A.    2157     (emphasis       added).          Additionally,       Ford’s

engineering experts indicated that the 1987 FMEA on which Sero

relied did not even apply to the Neases’ 2001 Ranger pickup

truck.       Rather,           James     Engle,      a    design      analysis    engineer,

                                                13
indicated that it is the 2004 FMEA that applies to the 2001

Ranger because it was “originated in February of ’97 and carried

forward.”      J.A. 1265.

      Finally,     Sero     testified        that    several      alternative      speed

control cable designs were available at the time and that Ford

could have made the 2001 Ranger safer by incorporating one of

these designs.        He admitted, however, that he had not tested any

of these alternative designs to determine whether any of them

would   have    prevented      the     accident       in    question.        In    Sero’s

opinion, testing of the alternative designs he identified was

unnecessary       because    the     designs        had    been   in   use    in   other

vehicles for years and were therefore “proven commodit[ies].”

J.A. 717.

      The district court instructed the jury that on plaintiffs’

strict liability claim, plaintiffs had to prove that the design

of   the   2001    Ford     Ranger     was    not     “reasonably      safe    for   its

intended use.”        J.A. 1922.        Although the court explained that

the “plaintiffs are only entitled to a reasonably safe product,

not to an absolutely safe product,” the court then instructed,

over Ford’s objection, that “[i]f a product can be made safer

and the danger may be reduced by an alternative design at not

substantial increase in price, then the manufacturer has a duty

to   adopt     such   a     design.”         Id.       During     closing     argument,



                                             14
plaintiffs’    counsel   highlighted      the    safer   alternative      design

instruction:

           . . .   If a product can be made safer and the
     danger reduced by an alternative design or device at
     no substantial increase in cost, then the manufacturer
     has a duty to adopt such design. All that means is if
     you find that one of the other designs was safer and
     it wasn’t going to cost very much . . . [t]hen you can
     find that Ford breached its duty.
J.A. 1960.

     The jury returned a verdict for the Neases on the strict

liability count and awarded damages of $3,012,828.35.                The jury

returned   defense   verdicts   on     the      negligence    and   breach    of

warranty counts.

    After trial Ford filed a Renewed Motion for Judgment as a

Matter of Law pursuant to Rule 50(b).              First, Ford argued that

“there was insufficient evidence to support the jury’s verdict

for strict liability because the claim was dependent upon the

testimony of Plaintiffs’ expert . . . Sero.”                 J.A. 3477.      And,

Ford argued, as it had prior to trial, that Sero’s testimony

should not have been admitted because Sero was unqualified to

testify as an expert and that Sero’s opinions should have been

excluded under Daubert.       Specifically, Ford argued that “Sero

never demonstrated unidirectional binding of Mr. Nease’s speed

control cable, he did not attempt to simulate his theory, he did

not conduct any tests that a foreign substance could withstand

the seven-pound spring pressure, [and] he did not demonstrate


                                     15
alternative designs were equally or more safe.”                           J.A. 3478.      The

district court denied the Rule 50 motion, concluding that Sero’s

methodology was reliable because he used the FMEA methodology

used by Ford and that the borescope examination was “consistent

and trustworthy and what historically [was] used in failure to

decelerate cases.”         J.A. 3479.

      Alternatively, Ford moved for a new trial pursuant to Rule

59(a)(1)(A),        arguing    that   the         verdict    should        be    set    aside

because the district court issued an improper “duty to adopt”

jury instruction as to safer alternative designs.                                Ford also

contended that the district court erroneously admitted evidence

of other incidents involving Ford vehicles with an allegedly

defective     speed      control    assembly        unit.      The        district      court

denied the motion for a new trial on both grounds.                               The court

did   not    expressly     reject     Ford’s       position        that    the    “duty    to

adopt”      instruction       was   incorrect        under     West        Virginia      law.

Instead,     the    district    court    concluded          that    even    if    the    jury

instruction        was   erroneous,     it    was    harmless       because       the    jury

found that the product was defective and not reasonably safe,

and thus the jury did not need to reach the question of the duty

to adopt a safer alternative design.                  Additionally, the district

court noted that the jury instructions were otherwise correct

and informed the jury that the Neases were not entitled to an

absolutely safe product.            Finally, the district court ruled that

                                             16
even if the admission of evidence regarding other incidents was

erroneous,      it    was     harmless       in    view     of    court’s    limiting

instruction to the jury that it “only consider the alleged other

incidents for the limited purpose of determining whether Ford

had notice of the defect” and not “as evidence that the 2001

Ford Ranger was defective.”            J.A. 3486.

      Ford appeals, arguing that the district court incorrectly

admitted     Sero’s    expert        testimony       in    contravention     of   the

requirement that such testimony be reliable under Daubert and

its progeny; that the district court’s erroneous “duty to adopt”

jury instruction was not harmless in view of the fact that it

was the only instruction that counsel for Nease highlighted in

his   closing    argument       to    the    jury;    and    that    the    erroneous

admission of other incident evidence was not rendered harmless

by    the   district        court’s    limiting       instruction      because    the

limiting instruction did not apply to the other incidents at

issue.      To resolve this appeal, we need only address Ford’s

Daubert argument.

                                            II.

      Ford contends that the district court erroneously denied

its motion to exclude Sero’s opinion that Ford’s design of the

speed control assembly in the 2001 Ford Ranger was defective and

that Ford could have used a different design that would have

prevented    Nease’s    accident.           We    review    the   district    court's

                                            17
application of Daubert for abuse of discretion.                    See Anderson v.

Westinghouse Savannah River Co., 406 F.3d 248, 260 (4th Cir.

2005).      “If the district court makes an error of law in deciding

an evidentiary question, that error is by definition an abuse of

discretion.”          Id.    (internal        quotation    marks    omitted).        A

district      court   likewise       abuses     its   discretion    in    deciding   a

Daubert      challenge      if     its   conclusion     “rests     upon   a   clearly

erroneous factual finding.”                Bryte ex rel. Bryte v. American

Household, Inc., 429 F.3d 469, 475 (4th Cir. 2005).

A.   Daubert’s Applicability

       We first must visit the question of whether Daubert even

applies under these circumstances.                    The Neases insist that it

does not.      We disagree; Daubert clearly applies here.

       In    Daubert,    the     Supreme      Court   addressed     an    evidentiary

issue       that   had      long     divided     federal    courts—whether        the

admissibility of expert scientific testimony was governed by the

“general acceptance” test established in Frye v. United States,

293 F. 1013 (D.C. Cir. 1923), 2 or the later-adopted standards set

forth in Federal Rule of Evidence 702, see 509 U.S. at 586–87 &

n.5.       Daubert held that the Federal Rules of Evidence superseded

Frye and that the admissibility of scientific evidence no longer

       2
       Under Frye, expert scientific testimony was admitted only
if the expert opinion was based on principles that were
“generally accept[ed]” in “the particular field in which it
belongs.” 293 F. at 1014.


                                           18
was limited to knowledge or evidence “generally accepted” as

reliable in the relevant scientific community.                 See 509 U.S. at

588–89.

       Thus, Daubert made clear that the governing standard for

evaluating proposed expert testimony was set forth in Rule 702,

which at the time provided:           “If scientific, technical, or other

specialized    knowledge       will    assist    the     trier        of   fact     to

understand    the   evidence    or    to   determine     a   fact     in   issue,    a

witness qualified as an expert by knowledge, skill, experience,

training, or education, may testify thereto in the form of an

opinion or otherwise.”         Daubert, 509 U.S. at 588.               Implicit in

the text of Rule 702, the Daubert Court concluded, is a district

court’s gatekeeping responsibility to “ensur[e] that an expert’s

testimony both rests on a reliable foundation and is relevant to

the task at hand.”       Id. at 597 (emphasis added).

       Relevant evidence, of course, is evidence that helps “the

trier of fact to understand the evidence or to determine a fact

in issue.”    Id. at 591 (internal question marks omitted).                   To be

relevant under Daubert, the proposed expert testimony must have

“a valid scientific connection to the pertinent inquiry as a

precondition to admissibility.”            Id. at 592.

       With respect to reliability, the district court must ensure

that   the   proffered    expert      opinion   is   “based      on    scientific,

technical, or other specialized knowledge and not on belief or

                                        19
speculation, and inferences must be derived using scientific or

other valid methods.”              Oglesby v. Gen. Motors Corp., 190 F.3d

244,    250     (4th    Cir.   1999).               Daubert       offered    a    number     of

guideposts       to     help   a    district          court       determine       if     expert

testimony is sufficiently reliable to be admissible.                                First, “a

key question to be answered in determining whether a theory or

technique is scientific knowledge that will assist the trier of

fact will be whether it can be (and has been) tested.”                                 509 U.S.

at 593.       A second question to be considered by a district court

is “whether the theory or technique has been subjected to peer

review and publication.”                Id.     Publication regarding the theory

bears    upon    peer    review;        “[t]he      fact     of   publication       (or    lack

thereof) in a peer reviewed journal will be a relevant, though

not     dispositive,      consideration             in      assessing       the   scientific

validity of a particular technique or methodology on which an

opinion is premised.”              Id. at 594.              Third, “in the case of a

particular      scientific     technique,             the    court    ordinarily         should

consider the known or potential rate of error.”                               Id.       Fourth,

despite    the    displacement           of    Frye,      “‘general     acceptance’”         is

nonetheless       relevant         to     the        reliability        inquiry.            Id.

“Widespread      acceptance        can    be     an      important    factor      in     ruling

particular evidence admissible, and a known technique which has

been able to attract only minimal support with the community may

properly be viewed with skepticism.”                        Id. (citation and internal

                                               20
quotation     marks        omitted).           Daubert’s            list        of     relevant

considerations       is     not    exhaustive;           indeed,       the           Court    has

cautioned     that        this    “list      of        specific       factors              neither

necessarily nor exclusively applies to all experts or in every

case,” Kumho Tire Co. v. Carmichael, 526 U.S. 137, 141 (1999),

and that a trial court has “broad latitude” to determine whether

these   factors      are    “reasonable      measures          of    reliability             in   a

particular case,” id. at 153.

     The Neases contend that we can affirm because the district

court   was    not    obliged      to     perform        its    Daubert          gatekeeping

function in the first place:                   “Because the Daubert test for

assessing the validity of scientific evidence applies only to

novel   scientific     testimony,       it     does     not    apply       in        the   expert

field   of    engineering.”         Brief         of    Appellees          at    29.         This

bifurcated argument is dead wrong on both counts.

     First, Daubert itself makes clear that its application is

not limited to newfangled scientific theory, explaining that “we

do not read the requirements of Rule 702 to apply specially or

exclusively to unconventional evidence.”                       Daubert, 509 U.S. at

592 n.11.      The Court recognized the common-sense premise that

“well-established propositions are less likely to be challenged

than those that are novel,” id., but clearly never suggested

that longstanding theories are immune to a Daubert analysis.



                                          21
         Second, the Supreme Court made clear more than 17 years ago

in Kumho Tire that Daubert was not limited to the testimony of

scientists but also applied “to testimony based on ‘technical’

and ‘other specialized’ knowledge.”                             526 U.S. at 141.           Despite

having         cited        Kumho    Tire        in     their     brief,    the       Neases    are

apparently        unaware           that    the       very    issue   there          involved   the

application            of     Daubert       to        the    testimony     of     a     mechanical

engineer.         See id. at 141 (“This case requires us to decide how

Daubert applies to the testimony of engineers and other experts

who are not scientists.” (emphasis added)).                                 The Kumho Court

concluded that Rule 702 “applies to all expert testimony” as its

“language        makes        no    relevant          distinction     between         ‘scientific’

knowledge and ‘technical’ or ‘other specialized’ knowledge.                                      It

makes clear that any such knowledge might become the subject of

expert testimony.”                  Id. at 147.             The Kumho Court affirmed the

district court’s application of Daubert and decision to exclude

the engineering expert’s testimony as unreliable.                                      See id. at

158. 3        And, finally, if Kumho were not enough, this court has

also         sanctioned       the     application            of   Daubert       to    assess    the

reliability of expert engineering testimony.                                See Oglesby, 190

         3
       In so holding, the Supreme Court rejected the Eleventh
Circuit’s view that engineering testimony “[fell] outside the
scope of Daubert, [and] that the district court erred as a
matter of law by applying Daubert in this case,” Kumho Tire, 526
U.S. at 146, which is precisely the same argument the Neases
make here.


                                                      22
F.3d    at    250-51        (affirming      district       court’s       application        of

Daubert principles to testimony of a mechanical engineer and

concluding that the district court did not abuse its discretion

in excluding the engineer’s opinion as unreliable).

       Accordingly,         we    conclude         that    Daubert       most       certainly

applies to Sero’s testimony.                  We now turn to consider whether,

under    Daubert,      the       district     court       properly       admitted     Sero’s

testimony.

B.    The     District        Court’s    Application         of    Daubert      to    Sero’s
Opinions

       As    we   already        explained,        Rule    702     imposes      a    special

gatekeeping       obligation       on   the    trial      judge    to    ensure      that   an

opinion offered by an expert is reliable.                         And although a trial

judge has broad discretion “to determine reliability in light of

the particular facts and circumstances of the particular case,”

Kumho, 526 U.S. at 158, such discretion does not include the

decision “to abandon the gatekeeping function,” id. at 158–59

(Scalia, J., concurring).

       In    ruling    on    Ford’s     motion      in    limine    to    exclude     Sero’s

testimony as unreliable under Daubert, the district court simply

dismissed “[e]very argument raised by [Ford]” as “go[ing] to the

weight, not admissibility, of [Sero’s] testimony.”                              J.A. 526.

The court did not use Daubert’s guideposts or any other factors

to assess the reliability of Sero’s testimony, and the court did


                                              23
not make any reliability findings.                  Indeed, the district court

referred neither to Rule 702 nor to Daubert.                   We are forced to

conclude that the court abandoned its gatekeeping function with

respect to Ford’s motion in limine.

      In denying Ford’s post-trial Rule 50(b) motion for judgment

as a matter of law (which renewed Ford’s argument that Sero’s

opinion should have been excluded under Daubert), the district

court again “[found] that Ford’s arguments go to the weight the

jury should afford Mr. Sero’s testimony, not its admissibility.”

J.A. 3481.      Although the district court this time cited Daubert

and stated that, according to Sero, “the methodology he employed

is consistent and trustworthy and what historically is used in

failure to decelerate cases,” J.A. 3479, the court repeatedly

emphasized that Ford effectively raised its objections to Sero’s

opinion through cross-examination.                  For the district court to

conclude that Ford’s reliability arguments simply “go to the

weight    the    jury   should    afford     Mr.     Sero’s   testimony”       is   to

delegate   the    court’s    gatekeeping          responsibility    to   the   jury.

“The main purpose of Daubert exclusion is to protect juries from

being swayed by dubious scientific testimony.”                     In re Zurn Pex

Plumbing Prods. Liab. Litig., 644 F.3d 604, 613 (8th Cir. 2011).

The   district     court’s       “gatekeeping        function”     under   Daubert

ensures    that    expert    evidence        is    sufficiently     relevant        and

reliable when it is submitted to the jury.                    Rather than ensure

                                        24
the reliability of the evidence on the front end, the district

court effectively let the jury make this determination after

listening to Ford’s cross examination of Sero.

      In sum, the district court did not perform its gatekeeping

duties   with   respect     to   Sero’s     testimony.      The   fact    that    an

expert   witness      was    “subject       to    a   thorough    and    extensive

examination” does not ensure the reliability of the expert’s

testimony; such testimony must still be assessed before it is

presented to the jury.           McClain v. Metabolife Int’l, Inc., 401

F.3d 1233, 1238 (11th Cir. 2005).                 Thus, we are of the opinion

that the district court abused its discretion here “by failing

to act as a gatekeeper.”              Id.; see Kumho, 526 U.S. at 158–59

(Scalia, J. concurring) (“[T]rial-court discretion in choosing

the manner of testing expert reliability . . . is not discretion

to abandon the gatekeeping function . . . [or] to perform the

function inadequately.”).

C.   Sero’s testimony should have been excluded under Daubert

1. Sero’s testimony that the speed control assembly                       was    not
reasonably safe because it was susceptible to binding

      “[A] plaintiff may not prevail in a products liability case

by   relying    on   the    opinion    of    an   expert   unsupported     by    any

evidence such as test data or relevant literature in the field.”

Oglesby, 190 F.3d at 249 (internal quotation marks omitted).                     “A

reliable expert opinion must [not] be based . . . on belief or


                                        25
speculation.”           Id. at 250.        One especially important factor for

guiding a court in its reliability determination is whether a

given theory has been tested.                     According to Daubert, “a key

question    to      be    answered    in     determining      whether    a   theory         or

technique is scientific knowledge that will assist the trier of

fact will be whether it can be (and has been) tested.”                          509 U.S.

at 593.

       Sero’s opinion had three critical components:                            that the

speed control assembly in the 2001 Ford Ranger was vulnerable to

binding    because        the   design      allowed     for   contaminant       to    lodge

between the speed control guide tube and the casing cap; that

such binding in fact occurred while Howard was driving his 2001

Ranger, resulting in the accident; and that there were safer

alternative speed control assembly designs available to Ford for

use in the 2001 Ranger.

       Testing was of critical importance in this case as Sero

conceded that the speed control cable in the Neases’ Ranger was

not    bound       or    wedged;     the    cable     “moved       freely”   when         Sero

performed      a    post-accident          inspection    of    the    Neases’    Ranger.

J.A. 676.      In fact, Sero admitted he has never seen any vehicle

with “post-crash binding.”                 J.A. 679.     Sero, however, conducted

no testing whatsoever to arrive at his opinion.                          Specifically,

he has never tested a 2001 Ford Ranger to determine whether it

is    actually      possible    for    enough     debris      to   accumulate        in    the

                                             26
casing cap during normal operation to resist the 7.2 pounds of

force exerted by the return springs to pull the throttle closed.

Sero conceded that he never ran any tests to confirm his theory:

        Q.   Now, as I understand it, . . . you have not
        demonstrated your unidirectional binding theory on Mr.
        Nease’s speed control cable, have you?

        A.    No, I have not.

        Q. You have not even attempted to simulate your speed
        control binding theory on Mr. Nease’s speed control
        cable, have you?

        A.    No.

        Q. You have not demonstrated your unidirectional
        binding theory [using] another 2001 Ford Ranger, have
        you?

        A.    No.

        Q. You have not even attempted to simulate your speed
        control malfunction theory with an exemplar 2001 Ford
        Ranger, have you?

        A.    No, I have not.

J.A. 678.

     Sero’s failure to test his hypothesis renders his opinions

on the cause of Howard’s accident unreliable.                   Although Sero’s

theory is plausible and “may even be right[,] . . . it is no

more than a hypothesis, and it thus is not knowledge, nor is it

based upon sufficient facts or data or the product of reliable

principles       and     methods   applied    reliably   to   the   facts   of   the

case.”       Tamraz v. Lincoln Elec. Co., 620 F.3d 665, 670 (6th Cir.

2010)        (internal     quotation    marks    and     alterations    omitted).

                                         27
Generally,          scientific             methodology            involves         “generating

hypotheses and testing them to see if they can be falsified.”

Daubert, 509 U.S. at 593.                   Sero presented a hypothesis only—he

failed to validate it with testing.

       Daubert      is    a    flexible         test     and    no   single      factor,     even

testing,       is   dispositive.                But      Daubert’s       other     reliability

markers likewise suggest that Sero’s testimony should not have

been    admitted         under      Rule    702.         Sero     has    not     published     or

otherwise subjected his theory to peer review.                                   Actually, it

would    hardly     be     possible        to     solicit       peer    review     since     Sero

conducted no tests and used no “methodology” for reaching his

opinions other than merely observing dirt on the speed control

assembly    components.              And,       for     this    same    reason,        we   cannot

assess the potential rate of error of Sero’s methodology—he did

not employ a particular methodology to reach his conclusions.

       Daubert also suggests that district courts, in performing

their gatekeeping functions, consider whether and to what extent

an     expert’s     theory          has    been        accepted      within      the    relevant

scientific or engineering community.                           See Daubert, 509 U.S. at

593-94.     Despite their contention that Daubert does not apply,

the Neases nonetheless suggest that the internal FMEA performed

by Ford in 1987, which Sero relied upon to support his opinion,

is widely accepted by engineers—Ford’s own engineers in this

case—as    a    method        for    identifying          design       defects.        The   FMEA

                                                  28
relied upon by Sero, however, does not establish that Sero’s

theory is widely accepted in the relevant engineering community.

       To begin with, the 1987 FMEA does not even apply to the

2001 Ranger; rather, the 2004 FMEA, which originated in 1997,

applied to the 2001 Ranger at issue here.                   In other words, Sero

rests his theory on an FMEA produced for different designs.                            The

1987 FMEA, therefore, lacks a “valid scientific connection to

the pertinent inquiry,” Daubert, 509 U.S. at 592, and is not

“relevant to the task at hand,” id. at 597.

       Moreover, to the extent Nease claims the FMEA performed by

Ford    in   1987   proves   that      the    speed   cable   is   susceptible          to

binding, he misconstrues the nature of the FMEA process.                           FMEA

is part of the design process itself; design engineers follow

this    method   well    before    the   design       is   complete    to    “identify

potential failure modes and rate the severity of their effects”

and “help engineers focus on eliminating product and process

concerns and help prevent problems from occurring.”                         J.A. 968.

As Ford engineer James Engle explained, “[t]he purpose [of] the

FMEA is to analyze the [current] design . . . [and] give[] the

engineer information beforehand . . . to let the engineer know

areas    where      he   needs    to   focus.”         J.A.    1279.         It   is     a

“brainstorming session” performed on the front end of the design

process to “identify any potential failure modes.”                          J.A. 2157.

And, in this case, because it is “conceivable” that “grime or

                                             29
some sort of debris [could] enter[] into the cable and caus[e]

sticking,” Ford naturally listed the potential binding of the

speed control cable “in a brainstorming session of [potential]

failure      modes.”        J.A.     2157.        But     Ford   included    numerous

“mitigating” features in its final design, such as an engine

cover, aimed at eliminating potential problems identified in the

FMEA.     J.A. 2157.       Ford also placed the throttle “high up on the

engine”      to    mitigate    the     intake        of   “[b]igger    and     heavier

particles [which] take more force to be . . . moved up . . . to

the    top   of    the    engine.”      J.A.      2157-58.       Additionally,    the

components of the speed control assembly were made of nylon that

had a slippery quality and “a very low coefficient of friction.”

J.A. 2433.

       In sum, the FMEA relied upon by Sero cannot be viewed as

having established that the binding of the speed control cable

was a recurring design problem in the 2001 Ranger.                             And it

cannot be used as a proxy for the testing that Sero failed to

do.     Ford’s FMEA process merely identifies conceivable design

failures; it does not produce them via testing.

2. Sero’s testimony that there were safer alternative designs
that Ford could have used in the 2001 Ranger

       To establish strict liability under West Virginia law, the

plaintiff must show that the “product is defective in the sense

that    it    is    not     reasonably        safe      for   its   intended     use.”


                                             30
Morningstar v. Black & Decker Mfg. Co., 253 S.E.2d 666, 683 (W.

Va. 1979).         “The standard of reasonable safeness is determined .

. . by what a reasonably prudent manufacturer’s standards should

have     been      at    the     time     the      product          was      made.”      Id.

Significantly, the West Virginia Supreme Court explained that

the determination of what a “reasonably prudent manufacturer’s

standards should have been at the time” requires a consideration

of “the general state of the art of the manufacturing process,

including design.”            Id. (emphasis added).

       Ford argues that West Virginia law, as articulated by the

Morningstar        court,      therefore      requires          a    products       liability

plaintiff to prove that a reasonably prudent manufacturer would

have adopted a safer design during the relevant time period.

The    Neases      disagree,     relying      on   a   couple         of   district    court

opinions that suggest the West Virginia Supreme Court “has not

stated       one   way   or    the    other     whether     a       design    defect   claim

requires proof of a safer alternative design of the allegedly

defective product.”            Mullins v. Ethicon, Inc., 117 F. Supp. 3d

810, 821 (S.D.W. Va. 2015) (internal quotation marks omitted);

Keffer v. Wyeth, 791 F. Supp. 2d 539, 547 (S.D.W. Va. 2011).

       While it is true that West Virginia law on the matter is

not crystal clear, we agree with Ford that Morningstar “can only

be    read    to   require     the    production       of   evidence         on   reasonable

alternative         design,      to     gauge      what     ‘should          have     been.’”

                                              31
Restatement (Third) of Torts: Products Liability § 2, Reporter’s

Note   (1998).         Although      Morningstar         does    not     use    the    phrase

“alternative         design,”    a   plaintiff      in    a     design    case,       for    all

practical purposes, must identify an alternative design in order

to establish the “state of the art.”                     See Church v. V.R. Wesson,

385    S.E.2d      393,   396    (W.    Va.    1989)     (holding        plaintiff      in    a

defective design case failed to establish a prima facie case

because plaintiff’s expert identified an alternative design that

was not feasible at the time of manufacture and thus failed to

prove that defendant’s design was not “state of the art”).

       Sero     testified       that    safer,      proven       design        alternatives

existed       during      the    relevant      time      period     that       would        have

prevented       Howard’s        accident.          One    preferable           alternative,

according       to    Sero,     incorporates        a    “nipple       wipe”      to    clean

contaminants off the cable as it moves.                           Another alternative

identified by Sero utilizes a “boot” which blocks debris and

grime from accumulating on the cable.                     And, a third alternative

design that Sero believed would have prevented Howard’s accident

simply had a larger gap between the guide tube and the casing

cap.     Sero pointed out that Ford had been using all of these

alternative design features for many years by the time the 2001

Ranger was produced.

       Sero, however, performed no tests or studies to determine

whether,      in     fact,      these   older,      long-standing          designs          were

                                              32
involved in fewer binding incidents.                        According to Sero, such

tests were unnecessary because designs such as the nipple wipe

had   been    in    use      for     50     years    and     therefore       were   “proven

elements.”      J.A. 669.            Similarly, he offered no data from any

other     studies    or      accident       records    to     prove    that     the      older

designs were less likely to bind than the one incorporated in

the Neases’ 2001 Ranger.               Sero instead simply proclaimed without

any   support      that      the    alternative       designs    he    identified         were

safer than the design of the speed control cable assembly in the

2001 Ranger.

      This    testimony            should     have    been     excluded       as    it    was

“unsupported       by     any      evidence    such    as    test     data    or    relevant

literature in the field.”                   Oglesby, 190 F.3d at 249 (internal

question marks omitted).                   The fact that the alternatives have

generally    been       in   use     for    decades    is    wholly    insufficient        to

prove that such designs were safer with respect to the alleged

binding incident and that reasonably prudent manufacturers would

have adopted them. 4




      4To the extent that the Neases argue that testing or other
comparative   analysis   of  Sero’s   alternative  designs   was
unnecessary because they were not novel designs, their argument
relies upon the same flawed understanding of Daubert that we
have already rejected.


                                              33
                              III.

     Without Sero’s testimony, the Neases cannot prove that the

design of the speed control assembly in the 2001 Ford Ranger

renders the vehicle “not reasonably safe for its intended use.”

Morningstar, 253 S.E.2d at 683.      Accordingly, we reverse the

district court’s denial of Ford’s post-trial motion for judgment

as a matter of law and remand the case to the district court for

entry of judgment in Ford’s favor.   And, because the granting of

judgment as a matter of law effectively ends this litigation, we

need not reach Ford’s challenges to the jury instruction and the

admission of prior incidents evidence.



                          REVERSED AND REMANDED WITH INSTRUCTIONS




                               34
