1

Revised November 3, 1998

UNITED STATES COURT OF APPEALS

FOR THE FIFTH CIRCUIT

No. 97-40365

JOHN BARTLEY, MIKE RUCKER, CHRIS LUKER,

WALTER HENRY, and TIM HUMBER,

Plaintiffs/Appellees/Cross-Appellants,

PLANET INSURANCE COMPANY,

Intervenor Plaintiff/Appellee,

VERSUS

EUCLID, INC., et al.,

Defendants,

EUCLID, INC.

Defendant/Intervenor Defendant/Appellant/Cross-Appellee.

Appeals from the United States District Court

for the Eastern District of Texas 

October 20, 1998

Before REAVLEY, DeMOSS and PARKER, Circuit Judges.

ROBERT M. PARKER, Circuit Judge:

The appeal in this diversity case challenges a jury verdict

and resulting judgment awarding four plaintiffs a total of $2.8
1John Bartley advised this court that he has settled his claim

and withdrawn his appeal.

2

million, exclusive of prejudgment and post-judgment interest, on

products liability and negligence theories against a manufacturer

of coal hauling vehicles. The plaintiffs cross-appeal to challenge

the jury finding that their own negligence contributed to their

injuries. We affirm.

I. PROCEEDINGS

Between May and October 1994, plaintiffs John Bartley1, Mike

Rucker, Chris Luker, Walter Henry and Tim Humber sued Euclid and

others asserting personal injury/products liability claims under

Texas law. The suits were filed in federal court invoking

diversity jurisdiction pursuant to 28 U.S.C. § 1332. In December

1995, the district court sua sponte consolidated these actions.

Euclid’s motions for summary judgment, challenging the admission of

plaintiffs’ expert testimony on the basis of Daubert v. Merrell Dow

Pharms., Inc., 509 U.S. 579 (1993), were denied, and the case was

tried to a jury. The district court entered judgment on the jury’s

verdict which found, inter alia, that Euclid’s coal haulers were

defective; that both Euclid and the plaintiffs were negligent; and

that the coal haulers caused injuries and damages to the

plaintiffs.

II. FACTS

Euclid designs, builds, and markets heavy equipment including
2Euclid’s long-nosed coal hauler is model 208 LDT.

3Euclid’s short-nosed coal hauler is model 322 NDT.

3

120-ton vehicles used for hauling coal at open pit coal mines.

Initially, Euclid’s coal haulers were built with the engine mounted

in front of the operator’s cab, which design was termed “longnosed.”2 In the mid-1970's, a new design, termed “short-nosed”

because its engine was moved back on the chassis so that it rested

partially under the operator’s cab, was introduced.3 The new

design differed from the earlier model in other ways, including

using a shorter wheel base, and a trailing arm suspension system

with rubber struts instead of steel springs. The short-nosed coal

haulers, which are the subject of this litigation, have better

visibility from the driver’s seat and better maneuverability, but

a considerably rougher ride. 

Plaintiffs, males ranging in age from 32 to 46 years, were all

employees of Texas Utilities Mining Company (“TUMCO”) and operated

Euclid short-nosed coal haulers in the course and scope of their

employment. They brought suit against Euclid claiming that they

had sustained back injuries as a consequence of long term

repetitious trauma and severe vibrations experienced while

operating Euclid’s short-nosed coal haulers.

III. ADMISSIBILITY OF EXPERT WITNESS TESTIMONY

a. Standard of review

Euclid contends that the district court abused its discretion
4

and violated its gate-keeping responsibilities under Daubert v.

Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993) by admitting

the plaintiffs’ expert testimony. We review district court rulings

on the admission of expert testimony for abuse of discretion. See

General Elec. Co. v. Joiner, ___U.S.___, 118 S. Ct. 512, 517

(1997); see also Moore v. Ashland Chemical, Inc., ___F.3d___ (5th

Cir. 1998)(en banc).

b. District court ruling

Plaintiffs’ experts fall into two categories. Dr. Charles

Aprill, Dr. Richard Bunch and Dr. Kelvin Samaratunga had formal

training in the medical and physical therapy fields and were called

to testify concerning causation. Arthur Chaseling and Geoff

McDonald have formal training in the field of engineering and were

called to testify regarding alleged design defects and potential

alternative designs. The district court specifically found that

both groups possessed sufficient qualifications to be considered

experts, that their proffered evidence was reliable and relevant

and that the probative value of the evidence was not “substantially

outweighed by any type of prejudice.”

The district court first considered whether the experts

satisfied the requirements set out by Federal Rule of Evidence 702

and Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579
4In January 1997, when the district court ruled on this motion,

the Fifth Circuit had not squarely addressed whether Daubert

applied to “non-scientific” expert testimony. The district court

noted that uncertainty, but found it to be of no consequence to the

determination of the motion, because all of the experts satisfied

the requirements of Daubert. The subsequent decision in Watkins v.

Telsmith, Inc., 121 F.3d 984 (5th Cir. 1997), holding that Daubert

is not limited to “scientific knowledge,” is therefore satisfied by

the district court’s analysis. 

5

(1993).

4

The Federal Rules of Evidence provide:

Rule 702. Testimony by Experts

If scientific, technical, or other specialized knowledge

will assist the trier of 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.

The district court began its analysis by acknowledging that, under

Texas law, plaintiffs’ medical causation evidence, as well as the

engineering evidence, are subject to the standards set out by the

Supreme Court in Daubert. 

The district court listed the non-exclusive Daubert factors

which it applied: 1) whether a theory or technique can be or has

been tested; (2) whether the theory has been subjected to peer

review and publication; (3) whether a potential rate of error has

been established; and (4) whether the theory is “generally

accepted” within the scientific community. See Daubert, 509 U.S.

at 593-94. The district court then cited United States v. Downing,

753 F.2d 1224 (3rd Cir. 1985) in support of three additional

factors that the district court found instructive to a reliability
6

determination:(1) the existence of a body of literature dealing

with a particular topic or technique; (2) the qualifications and

professional stature of the witness in question; and (3) the

relationship of the current theory to other methods of analysis. 

c. Causation experts

Euclid specifically challenges the district court finding that

Plaintiffs’ causation experts offered reliable evidence.

Dr. Aprill, a medical doctor specializing in diagnostic

radiology, evaluated Plaintiffs’ spinal problems and researched the

cause of those problems. Aprill’s research involved comparing the

Magnetic Imaging Resonance (“MRI”) scans of 90 individuals who

drove the coal haulers that are the subject of this case with the

MRI scans of 80 back pain patients, age and sex matched to the

hauler drivers. Aprill employed mainstream scientific research

techniques to preclude bias in his conclusions. These included

Aprill reading MRIs without knowing whether the scans were taken

from hauler drivers or from the control group, as well as

intraobserver reliability checks by which a colleague selected

random MRIs for double readings without Aprill’s knowledge. He

also testified concerning the results of another study of endplate

fractures conducted in Minneapolis, finding that the MRIs of 38% of

asymptomatic Minneapolis subjects revealed broken endplates

compared to 41% in his study. 

Aprill concluded that the MRIs of the hauler driver group
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demonstrated multiple endplate fractures at multiple levels in the

dorsal and lumbar spines and that accelerated disc degeneration

occurred more often and at more levels in the hauler driver group

than in the comparable group of people with back pain. He termed

this finding statistically significant. The multiple endplate

fractures demonstrated by the coal hauler population suggested to

Aprill that those individuals were subject to repetitive vertical

compression resulting in fractured endplates. Aprill’s opinions

were supported by an article appearing in 1992 in Clinical

Biomechanics, stating that exposure to whole body vibrations causes

structural damage to the endplate and subchondral bone. Aprill

stated that he found this “fingerprint” condition throughout the

hauler driver population. Although endplate abnormalities are

fairly common, the drivers had not only more end plate fractures

than the control population, but also an uncommon distribution of

these fractures. Specifically, Aprill testified that in mature

human populations most injuries appear in the lumbar (lower back)

region, with cervical (neck) injuries next and dorsal spine

injuries a distant third. The number of dorsal injuries Aprill

found in the hauler driver population was very unusual. Further,

the control group included individuals who had exposure to other

risk factors identified by Euclid as possibly causing Plaintiffs’

back injuries, including being over-weight, smoking, and truck

driving. However, the significant number and characteristic
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distribution of injuries pointed to hauler driving as the single

risk factor resulting in the “fingerprint” injuries which showed up

in Aprill’s study.

Dr. Samaratunga, the plaintiffs’ treating neurosurgeon, relied

partially on Aprill’s MRI study for his conclusion that the

endplate fractures were caused by whole body vibrations. Dr.

Bunch, a physical therapist and ergonomics expert, testified that

he had performed an ergonomic assessment of the coal haulers and

concluded that the coal haulers contributed to the plaintiffs’

injuries.

The district court, after reviewing the curriculum vitae of

Dr. Aprill, Dr. Samaratunga and Dr. Bunch, found that each of these

witnesses met the requirements of Rule 702 for designation as

expert witnesses in this matter. In addition to the doctors’

credentials, the court noted that there is a body of literature

dealing with repetitive trauma back injuries, the doctors’ theories

can be tested, and that the methodology that the doctors used

derived from other accepted methodologies. Based on these facts,

the district court determined that the testimony was reliable under

the standards set forth in Daubert.

Euclid attacks the district court’s finding that these

causation experts provided reliable testimony. First, Euclid

contends that the “mere existence” of a body of literature on a

given subject does not speak to the question of reliability.
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Second, they point out that the qualifications and professional

stature of a witness, standing alone, do not evidence reliability.

Third, they complain that the district court’s conclusion that the

experts’ theories are “derived from methodology which relates to

other accepted methodologies” is not helpful in determining

reliability. Finally, they list those Daubert factors which do not

point to reliability in this case: the potential rate of error in

the causation witnesses’ work was not established, the “general

acceptance” of their conclusions was not established, and Dr.

Samaratunga was allowed to testify concerning causation, when his

area of expertise was established as treatment of back pain, not

etiology.

Given the broad discretion vested in trial courts to “keep the

gate” for the purpose of admitting or excluding opinion testimony,

we cannot say that the district court abused its discretion in this

case. See Moore v. Ashland Chemical, Inc., ___ F.3d ___ (5th Cir.

1998)(en banc). Euclid asserts that each factor, standing alone,

may not have been enough to support the admission of opinion

testimony. However, the district court considered the Daubert

factors in the aggregate, and determined that, on balance, the

experts’ opinions were sufficiently reliable to merit admission

into evidence and testing in the fire of cross examination and

contrary evidence. We find that the district court did not abuse

its broad discretion in that exercise. See General Electric Co. v.
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Joiner, ___ U.S. ___, 118 S. Ct. 512, 517 (1997); see also Moore v.

Ashland Chemical, Inc., ___ F.3d___ (5th Cir. 1998)(en banc).

c. Liability experts

Although Euclid generally complains of the admission of

testimony by liability experts McDonald and Chaseling, the only

basis for the challenge advanced on appeal concerns the manner by

which Chaseling measured the vibration levels in the coal haulers.

Euclid contends on appeal, as it did at trial, that it was

inappropriate for Chaseling to measure the vibrations in the coal

haulers by attaching an accelerometer to the metal frame below the

seat. Chasling responded to that contention, testifying that,

pursuant to International Standards Organization (“ISO”) standards,

it is permissible to measure the vibrations from the frame rather

than from the seat as long as the transmission characteristics of

the seat cushion are taken into account when calculating the actual

vibration. Chasling testified further that he believed that

measuring the vibration from the frame gave better comparable

results from truck to truck because the condition of the seating

material varies widely. 

Euclid also complains that Chaseling turned on the

accelerometer in 16-second bursts only when told to do so by people

who were suing Euclid, gathering less than seven minutes of

vibration data over a fifteen hour span of time, which resulted in

vibration data that was unreliable. Chaseling explained during his
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testimony that he was attempting to record vibration measurements

when the hauler was in a loping mode. For this he relied on the

input of the hauler drivers to advise him when they felt the

machine phase into that mode.

The district court noted that, “[a]s a general rule, questions

relating to the bases and sources of an expert’s opinion affect the

weight to be assigned that opinion rather than its admissibility

and should be left for the jury’s consideration.” Viterbo v. Dow

Chemical Co., 826 F.2d 420, 422 (5th Cir. 1987). The question for

the district court was whether the “analytical gap” between the

causation opinion offered by the expert and the scientific

knowledge and available data advanced to support that opinion is

too wide. Moore v. Ashland Chemical Inc., F.3d (5th Cir.

1998). Here the district court determined that it was not.

[T]hese witnesses’ theories can be tested, their

qualifications are adequate, literature exists dealing

with common design principals and methodologies for

testing such designs, and the methods from which these

opinion were reached are related to other methodologies

and theories in the area of engineering safety and

design. In the Court’s opinion, these factors render

this evidence reliable under Daubert.

Memorandum Opinion and Order, January 2, 1997, at 6. We conclude

that the district court did not abuse its discretion in finding

that the expert testimony offered by Chaseling and McDonald was

reliable and relevant and therefore admissible, and that it was

within the province of the jury to weigh the credibility of that

evidence in light of Euclid’s criticism that Chasling’s methods for
5The district court instructed the jury that all claims in this

case must be established by a preponderance of the evidence, which

“means evidence that persuades you that the plaintiffs’ claims are

more likely true than not true.” Charge to the Jury, at 11.

Neither party challenges the district court’s articulation of the

applicable burden of proof. 

12

testing vibration levels yielded inaccurate results. 

IV. SUFFICIENCY OF THE EVIDENCE

Euclid moved for judgment as a matter of law based on the

insufficiency of the evidence to support the plaintiffs’ products

liability and negligence claims. The district court denied the

motion. We review that ruling de novo, applying the same standards

employed by the district court. See Gutierrez v. Excel Corp., 106

F.3d 683, 686 (5th Cir. 1997). “All evidence with all reasonable

inferences must be considered in the light most favorable to the

nonmoving party.” Id. Judgment as a matter of law should have

been granted if there was “no legally sufficient evidentiary basis

for a reasonable jury to find for” the plaintiffs on issues they

bore the burden of proving. FED.R.CIV.P. 50(a).

The jury found that the preponderance of the evidence5

established that there were design and marketing defects in the

coal haulers at the time they left the possession of Euclid that

were a producing cause of the plaintiffs’ injuries. The jury also

found that the preponderance of the evidence established that

negligence by both Euclid and the plaintiffs proximately caused the

injuries in question. On appeal, Euclid challenges the sufficiency
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of the evidence as to design defects, marketing defects, Euclid’s

negligence and causation. 

a. Strict liability design defect

In determining whether a product is defectively designed, “the

jury must conclude that the product is unreasonably dangerous as

designed, taking into consideration the utility of the product and

the risk involved in its use.” American Tobacco Co., Inc. v.

Grinnell, 951 S.W.2d 420, 432 (Tex. 1997). Liability for a design

defect may attach even if the defect is obvious or apparent.

Turner v. General Motors Corp., 584 S.W.2d 844, 850 (Tex. 1979).

Whether a product has a design defect is evaluated in the light of

economic and scientific feasibility of safer alternatives.

Boatland of Houston, Inc. v. Bailey, 609 S.W.2d 743, 756 (Tex.

1980). 

We find no merit in Euclid’s argument that the evidence is not

sufficient to support the jury’s verdict because plaintiffs’

experts did not use the words “unreasonably dangerous.” Although

an expert may testify to an ultimate issue, such testimony is not

required to support the jury’s verdict. See FED.R.EVID. 704(a).

Rather, we must look to all the evidence, drawing all reasonable

inferences in favor of the plaintiffs in evaluating the sufficiency

of the evidence. See Crosthwait Equipment Co., Inc. v. John Deere

Co., 992 F.2d 525, 528 (5th Cir. 1993).

Chasling testified that the vibration of the hauler violated
6Euclid points out that the ISO standards are not laws nor

regulations, but are voluntary consensus standards for evaluation.

Therefore, they contend, without specifically challenging the

admission of evidence concerning ISO standards, that their failure

to comply with the standards is not relevant to the issues in this

case. However, evidence concerning ISO standards was before the

jury, and we conclude that such evidence was relevant and the jury

was free to assign whatever weight to the evidence that they

determined was appropriate. 

14

the health and safety thresholds of International Safety

Organization (“ISO”) Standard 2631.6 Under that standard, the

hauler drivers should not be exposed to vibrations in excess of

established levels for more than 1.6 hours in a 24 hour period.

The plaintiffs were routinely exposed to vibrations in excess of

ISO standards for a majority of their 8 to 12 hour shifts. It was

not simply the intensity of the vibrations but the vector of forces

caused by a combination of vertical and longitudinal vibrations

that produced injury. Evidence supports a determination that the

“geometry” of the short-nose haulers, i.e. the shorter wheel base

and placement of the engine, caused the vibrations. Those

vibrations were exacerbated by the substitution of rubber struts

for the steel springs which had been used in the long-nose haulers.

The evidence identified Euclid’s own long-nose hauler as a safe,

feasible alternative from both an engineering and economic

perspective. Euclid focuses on evidence that the short-nose design

was a response to user demand for better maneuverability and

visibility, arguing that such demand made the older design obsolete

and therefore non-feasible. While Euclid’s line of reasoning was
15

certainly relevant, this court is not empowered to sit as a super

jury, substituting its view for the jury’s assessment of the weight

and credibility to assign to the conflicting feasibility evidence.

See Gutierrez v. Excel Corp., 106 F.3d 683, 687 (5th Cir. 1997).

Based on the foregoing, we find that the evidence before the

jury was sufficient to support its conclusion that the short-nosed

coal haulers are unreasonably dangerous as designed.

b. Negligence: marketing defect, failure to warn. 

Euclid challenges on appeal the jury’s determination that

there was a defect in the marketing of the coal haulers at the time

these products left the possession of Euclid.

Under Texas law, negligence consists of four essential

elements: (1) a legal duty owed to the Plaintiff by the Defendant;

(2) a breach of that duty; (3) an actual injury to the Plaintiff;

and (4) a showing that the breach was a proximate cause of the

injury. See Williams v. Southern Pacific Transp. Co., 804 S.W.2d

132, 138 (Tex. App.--Houston [1st Dist.] 1990, writ denied). While

strict liability focuses on the condition of the product,

negligence looks at the acts of the manufacturer and determines if

it exercised ordinary care in designing and producing its product.

American Tobacco Co., Inc. v. Grinnell, 951 S.W.2d 420, 437 (Tex.

1997). 

A product may be unreasonably dangerous because of a defect in

marketing. See Caterpillar, Inc. v. Shears, 911 S.W.2d 379, 382
16

(Tex. 1995). A defendant’s failure to warn of a product’s

potential dangers when warnings are required is a type of marketing

defect. See id. A manufacturer has a duty to warn if it knows or

should know of the potential harm to a user because of the nature

of its product. See American Tobacco Co., Inc. v. Grinnell, 951

S.W.2d 420 (Tex. 1997). Euclid contends that the evidence was

insufficient to support the jury’s verdict that the short-nosed

haulers were unreasonably dangerous and that Euclid knew or should

have known of a potential harm to users because of the nature of

its product. Euclid does not dispute that it failed to warn

plaintiffs of unreasonably dangerous characteristics of its shortnose haulers.

A manufacturer has a duty to test and inspect his product to

uncover scientifically discoverable dangers before the product is

sold. See Owens-Corning Fiberglas Corp. v. Malone, 916 S.W.2d 551,

562 (Tex.App.--Houston [1st Dist.], 1996, writ granted). A product

must not be made available to the public without disclosure of

those dangers that the application of reasonable foresight would

reveal. See id. There is evidence in the record that Euclid never

ride-tested the short-nosed hauler before placing it on the market.

In 1978, after an Australian purchaser complained about the rough

ride of its short-nosed hauler, Euclid performed some ride tests

specifically on the Australian hauler and found the ride to be

unacceptable. However, the short-nosed haulers were still not
7John Stoneman, the managing director of Morgan Equipment

Company, the Euclid dealer that sold the short-nosed hauler to the

Australian mine, testified concerning the lengthy history of

attempts by both Morgan and Euclid to determine the cause of and to

remedy the ride problems in the Australian hauler. 

17

tested by Euclid in accordance with ISO procedures or otherwise,

even though Euclid’s chief engineer admitted that he was aware of

the ISO procedures for whole body vibration testing. Euclid made

no design changes in response to the reports made after the

Australian testing, and even canceled its Ride Improvement Program.

Further, there was evidence that Euclid knew or should have

known that three people sustained injuries caused by the rough ride

of the short-nosed hauler sold to the Australian mine. Euclid took

the position that the complaints were limited to one machine in

Australia. The district court admitted into evidence a letter

which had been sent to Morgan Equipment, an authorized Euclid

dealer, which referenced “3 recent injuries (1 compensatable)

claimed to be caused by the rough ride of” the Euclid short-nosed

hauler. The letter also references “representations by the union

on driver discomfort....” Euclid contends that this is not

evidence of Euclid’s negligence because there is no evidence that

anyone at Euclid saw the letter and because it is not clear that

the injuries referred to in the letter were same type injuries

experienced by plaintiffs in this case. Euclid acknowledges that

they were aware that the Australian short-nosed hauler had an

unacceptably rough ride7, but points to evidence that the
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Australian hauler was a “lemon,” and that it was specially modified

to the customer’s specifications, operated on rougher roads, and

that these differences between the Australian hauler and the Texas

haulers excused Euclid from warning the Texas buyers about the

Australia rough ride problems. 

The trial record contains evidence upon which a rational jury

could base a rejection of Euclid’s position. Euclid entered into

a contract with Battelle Laboratories in February 1978, later

expanded in May 1978, under which Euclid would pay $17,500 to

Battelle to solve the “ride problem” in its short-nosed haulers.

Euclid also initiated a Ride Improvement Program during 1978, which

was later discontinued. These efforts, combined with the letter

and the failure to test the equipment prior to marketing is

sufficient to support the jury’s conclusion that Euclid knew or

should have known of the potential harm to users because of the

rough ride problems of the short-nosed haulers. 

c. Causation

Causation is an element of both the plaintiffs’ strict

products liability claims and their negligence claims. See Union

Pump Co. v. Allbritton, 898 S.W.2d 773, 775 (Tex. 1995). Strict

liability requires proof of a producing cause, while proximate

cause is the test in negligence actions. See General Motors Corp.

v. Saenz, 873 S.W.2d 353, 357 (Tex. 1993). 

A producing cause is an “exciting or contributing cause which
8Producing cause requires a lesser burden than proximate cause

because it does not require foreseeability. Purina Mills, Inc. v.

Odell, 948 S.W.2d 927, 935 (Tex.Civ.App. - Texarkana 1997, writ

denied).

19

in the natural sequence, produced the injuries or damages

complained of.” Haynes & Boone v. Bowser Bouldin, Ltd., 896 S.W.2d

179, 181 (Tex. 1995). 

Proximate cause, on the other hand, consists of both cause in

fact and foreseeability. See Union Pump Co. v. Albritton, 898

S.W.2d 773, 775 (Tex. 1995). Cause in fact means that a

defendant’s acts or omissions were a substantial factor in bringing

about a plaintiff’s injury. Id. Foreseeability is satisfied by

showing that the actor, as a person of ordinary intelligence,

should have anticipated the danger to others by his negligent act.

See McClure v. Allied Stores of Tex., Inc., 608 S.W.2d 901, 903

(Tex. 1980). Foreseeability does not require the actor to

anticipate the particular accident, but only that he reasonably

anticipate the general character of the injury. See El Chico Corp.

v. Poole, 732 S.W.2d 306, 313 (Tex. 1987).8

There need not be direct proof of causation. The jury may

infer proximate cause from the surrounding circumstances. See

Mosley v. Excel Corp., 109 F.3d 1006, 1009 (5th Cir. 1997). If a

negligent act actively aids in producing an injury, it need not be

the sole cause, but it must be a concurring cause, and such as

might reasonably have been contemplated as contributing to the
20

result. See McClure, 608 S.W.2d at 904. However, causation “must

be established by probative evidence, not by mere conjecture or

guess.” Gutierrez v. Excel Corp., 106 F.3d 683, 687 (5th Cir.

1997). 

The question for this court is whether there was sufficient

evidence to support the jury’s conclusion that Plaintiffs’ back

injuries were, more likely than not, caused by driving Euclid’s

coal haulers. Of course, there is not a precise fit between

science and the applicable legal burdens of proof. However, when

the incidence of a disease or injury is sufficiently elevated due

to exposure to a purported source of injury, a plaintiff can raise

a fact question on causation by presenting evidence that he was

exposed to that substance and exhibits the disease or injury. See

Merrell Dow Pharms., Inc. v. Havner, 953 S.W.2d 706 (Tex. 1997),

citing Daubert v. Merrell Dow Pharms., Inc., 43 F.3d 1311, 1320 n.

13 (9th Cir. 1995)(on remand). The question remains what quantum

of elevation is sufficient to satisfy the preponderance of evidence

burden of proof. The Texas Supreme Court seemingly answered this

question, holding that epidemiological evidence should show that

the risk of an injury or condition in the exposed population was

more than double the risk in the unexposed or control population.

Havner, 953 S.W.2d at 716. However, an intermediate Texas

appellate court subsequently addressing the Havner opinion takes

the position that Havner did not “set any strict rules regarding
9Havner amounts to the Texas Supreme Court’s definition of “more

likely than not burden of proof.” See Havner, 953 S.W.2d at 717.

Arguably, the definition of the applicable burden of proof is

procedural rather than substantive, and therefore controlled by

federal rather than state law. See Gasperini v. Center for

Humanities, Inc., 518 U.S. 415, 426 (1996)(noting that

classification of a law as “substantive” or “procedural” is

“sometimes a challenging endeavor.”) The Fifth Circuit has not

weighed in on the question of whether evidence must show more than

doubling of the risk to support a jury’s finding of causation. The

federal circuits which have considered the question have reached

diverse results. See Havner, 953 S.W.2d at 716 (listing cases

demonstrating the split). The parties neither briefed nor argued

the issue, and it is not outcome determinative in this case.

Therefore, we decline to reach it.

21

what types of evidence would be sufficient or not sufficient to

support a finding of causation.” Minnesota Mining and

Manufacturing Co. v. Atterbury, ___ S.W.2d ___, ___ (Tex.App. --

Texarkana 1998)(1998 WL 436916 at *15). There is no requirement

that a party must have reliable epidemiological evidence of a

relative risk of 2.0 or greater. Id. Reliable evidence of

relative risk less than 2.0 can be considered, but must be

supported by other credible, reliable evidence of causation. Id.

Further, epidemiological evidence with a relative risk of 2.0 or

greater does not automatically pass a sufficiency review. Id.

Assuming, without deciding, that Havner’s rule controls,9 the

evidence before the jury more than satisfies the relative risk of

2.0 standard. According to Aprill’s testimony, the plaintiffs’

condition is revealed in their MRIs as a “fingerprint” of a

characteristic number and distribution of end plate fractures which

is essentially unique to hauler drivers. While 68% of the control
22

group exhibited some evidence of end plate fractures, none of those

individuals exhibited the characteristic injuries found in 90% of

hauler drivers, that is, a pattern of back pathology discernable

from the number, severity and distribution of end plate fractures.

While the test formulated in Havner, if applicable, requires

incidence of “fingerprint” conditions in the hauler driver

population double that of the control group, the evidence

established that the fingerprint condition found in 90% of the

hauler drivers existed in 0% of the control population. Aprill

additionally testified that, on average, the hauler drivers had

twice as many end plate fractures as the control group. Aprill

explained to the jury that end plate fractures are caused by

vertical compression stress on the spine. If a person falls and

lands hard on his buttocks, this may cause an individual end plate

to crack. Such injuries appear most often at the top of the lumbar

spine. However, long-term exposure to whole body vibration causes

multiple end plate fractures throughout the spine. The control

group exhibited the former pattern of end plate fractures, while

the hauler drivers exhibited the latter. This evidence is

sufficient to support the jury’s verdict on the issue of causation

under the Havner standard. 

V. STATUTE OF LIMITATIONS

a. The Texas Discovery Rule

In Texas, a personal injury action must be filed “not later
23

than two years after the day the cause of action accrues . . . .”

TEX.CIV.PRAC.&REM.CODE ANN. § 16.003(a). Generally, accrual occurs on

the date the plaintiff first becomes entitled to sue the defendant

based upon a legal wrong, even if the plaintiff is unaware of the

injury. Zidell v. Bird, 692 S.W.2d 550, 554 (Tex. App.--Austin,

1985, no writ). 

The “discovery rule” is an exception to this general rule.

See Moreno v. Sterling Drug, Inc., 787 S.W.2d 348, 351 (Tex. 1990).

Under the Texas discovery rule, the accrual of a cause of action is

deferred in cases in which the alleged wrongful act and resulting

injury were inherently undiscoverable at the time they occurred but

may be objectively verified. See S.V. v. R.V., 933 S.W.2d 1, 6

(Tex. 1996).

Euclid asserted at trial that the statute of limitations

barred the Plaintiffs’ claims and the issue was submitted to the

jury. The jury found that Plaintiffs failed to file their lawsuits

within two years of the date they first suffered injury. The jury

made an additional findings that 1) the plaintiffs filed their

lawsuits within two years of the date they first knew, or in the

exercise of reasonable diligence should have known, that their

injuries were caused by driving the coal haulers; 2) plaintiffs’

injuries were inherently undiscoverable; and 3) plaintiffs’

injuries were objectively verifiable. 

b. Standard of Review
24

On appeal, Euclid challenges the sufficiency of the evidence

to support the jury’s finding regarding the inherently

undiscoverable and objectively verifiable nature of the injuries.

Like the sufficiency of the evidence issues on liability, we review

this ground of error by considering all evidence, drawing all

reasonable inferences in the light most favorable to the nonmoving

party. Gutierrez v. Excel Corp., 106 F.3d 683, 686 (5th Cir.

1997). We will reverse the denial of Euclid’s motion for judgment

as a matter of law if there was not substantial evidence “such that

reasonable jurors might reach different conclusions...” Id. at

686-87.

c. Inherently undiscoverable injuries

An injury is “inherently undiscoverable” if it is by nature

unlikely to be discovered within the prescribed limitations period

despite due diligence. S.V. v. R.V., 933 S.W.2d at 7. Euclid

argues that because Plaintiffs were aware of a painful “backslapping” sensation while driving the coal haulers, their injuries

were immediately “discoverable.” Plaintiffs counter that, in spite

of the uncomfortable ride, they had no reason to suspect the

insidious damage that was occurring within their spines. We

conclude that the evidence was sufficient to support the jury’s

“inherently undiscoverable” finding. Repetitive trauma injuries

like those at issue in this case are not readily susceptible to

discovery at the time of a particular, individual contact. Rather,
25

the fractured endplates throughout the plaintiffs’ spines which

were discovered later, were “unexpected latent injur[ies] which

were unknown and unknowable at the time of the traumatic event.”

See Albertson v. T.J.Stevenson & Co., Inc., 749 F.2d 223, 233 (5th

Cir. 1984). 

d. Objectively verifiable injuries

Euclid contends that there is not legally sufficient evidence

to support the jury’s determination that the Plaintiff’s injuries

were objectively verifiable. Euclid relies on language from the

Texas Supreme Court’s opinion in S.V. v. R.V., 933 S.W.2d 1 (Tex.

1996): “For the purpose of applying the discovery rule, expert

testimony on subjects about which there is no settled scientific

view . . . cannot provide objective verification of [alleged wrong

and injury.]” Id. at 18. S.V. held that expert opinion regarding

recovered memories of childhood sexual abuse could not meet the

objective verifiability element for the Texas discovery rule. The

court noted the lack of consensus in the scientific community

concerning the reliability of recovered memory, id. at 17-18, but

noted that expert opinion coupled with other evidence could provide

the kind of verification required. Id. at 16. 

Here, the jury heard evidence that plaintiffs suffered

herniated intervertebral discs and degenerated spines, confirmed by

recognized diagnostic testing. We hold that such evidence, which

came in the form of testimony from medical experts, relying on long
10This issue is referred to in the record and in much of the

precedential jurisprudence as “contributory negligence” or

“comparative responsibility.” Texas law was modified in 1995 to

its present form which refers to the same concept as “Proportionate

Responsibility.” See TEX.CIV.PRAC.& REM. CODE ANN., Ch.33. 

26

accepted methods of reading and interpreting MRIs, is sufficient to

support the jury’s affirmative answer on the “objectively

verifiable” nature of the injuries. 

e. Limitation bar as to Appellee Humber

Euclid devotes a single sentence to its contention that a

unique limitations argument bars the claim of Tim Humber because a

doctor told him more that two years before he filed suit that

repetitious trauma had compromised his back. However, the jury

heard evidence that Humber’s doctor had actually diagnosed a

herniated disc and it was TUMCO that advised him to claim his

injury was due to repetitive trauma disease so that an injury date

could be established for workers’ compensation purposes. Such

evidence does not preclude a reasonable jury from finding that

Humber discovered that he suffered a repetitive trauma injury less

than two years before he filed suit or that his injury resulted

from driving the coal haulers. 

VI. PROPORTIONATE RESPONSIBILITY10

The district court reduced the award of damages to Plaintiffs

as a consequence of the jury’s findings concerning Plaintiffs’
11Question No. 4. For each person or product found by you to

have caused the injury, find the percentage caused by...

b. Chris Luker 30

Euclid, Inc. 70...

c. Mike Rucker 70

Euclid, Inc. 30...

d. Walter Henry 50

Euclid, Inc. 50...

e. Tim Humber 40

Euclid, Inc. 60.... 

27

proportionate responsibility for their injuries.11 A take nothing

judgment was entered as to Rucker because his proportionate

responsibility was found to be 70%. Plaintiffs filed a crossappeal, arguing that there is insufficient evidence to support the

jury’s findings regarding their proportionate responsibility for

their injuries and that they should have been granted a judgment as

a matter of law on that issue.

a. Was the issue preserved for appellate review?

Initially, we must determine whether Plaintiffs preserved the

right to appeal the jury’s proportionate responsibility findings.

Euclid contends that Plaintiffs failed to comply with the

requirements of FED.R.CIV.P. 50, thus precluding our review of the

sufficiency of the evidence to support the jury’s verdict on this

issue. Generally, sufficiency of the evidence is not reviewable on

appeal unless a pre-verdict motion for judgment as a matter of law

was made in the trial court at the conclusion of all the evidence.
28

See McCann v. Texas City Refining, Inc., 984 F.2d 667, 671 (5th

Cir. 1993). However, strict compliance with Rule 50 is not

necessary so long as the purposes of the requirement have been

satisfied. Greenwood v. Societe Francaise De, 111 F.3d 1239, 1244-

45 (5th Cir.), cert. denied, 118 S. Ct. 558 (1997). “These

purposes are met when the court and the [opposing party] are

alerted to the grounds on which the [complaining party] contends

the evidence is insufficient prior to the submission of the case to

the jury.” Id. at 1245.

In this case, the evidence closed shortly before noon on

Thursday, January 30, 1997. The trial court then considered

Euclid’s motion for judgment as a matter of law and began work on

the jury charge. After 6:00 p.m. the following day, after

completing what the court termed its “informal charge conference”

the court allowed the parties to go on the record with “comments,

requested instructions, and objections.” At that time, Plaintiffs

objected orally, on the record, to the submission of contributory

negligence to the jury on the ground that there was not legally

sufficient evidence to support the submission of the evidence to

the jury. The court overruled the objection. After the verdict

was returned, Plaintiffs filed a “renewed” motion for judgment as

a matter of law addressing the sufficiency of the evidence of

contributory negligence. 

It is undisputed that Plaintiffs failed to file a formal,
29

written, pre-verdict motion for judgment as a matter of law.

However, we find that Plaintiffs’ objection to the jury charge on

sufficiency of the evidence grounds served as the functional

equivalent of a formal pre-verdict motion. See Greenwood, 111 F.3d

at 1245, n.7 & 8; see also Wells v. Hico ISD, 736 F.2d 243, 251-52

(5th Cir. 1984). The issue of sufficiency of the evidence on

plaintiffs’ proportionate responsibility is thus preserved for

appellate review. 

b. Sufficiency of the evidence on proportionate responsibility

Plaintiffs contend that there is no evidence that any of the

Plaintiffs had an awareness of the cumulative trauma they were

suffering as a result of their exposure to Euclid’s coal haulers.

Nor, they argue, is there any evidence in the record to indicate

that any of the Plaintiffs should have had knowledge of the

dangerous and unsafe nature of the vibration levels they were

receiving while driving the coal haulers. 

Euclid answers that the evidence supports findings that

Plaintiffs were negligent and at least partially responsible for

their alleged physical injuries and damages. Euclid points to

evidence that the coal hauler, like any other vehicle, had a

rougher ride when road conditions were bad and the driver was

driving too fast. The record contains evidence that there was no

reason for driving the haulers at top speed and in fact TUMCO

management wanted its drivers to slow down. Further, there was
30

evidence that Rucker continued to smoke, though doctors had told

him smoking aggravates his back injury. 

Given evidence that the Plaintiffs knew the vibrations

worsened based on the speed the haulers were driven and that the

drivers drove the haulers faster than their employer recommended,

we find sufficient evidence to support the proportional negligence

findings of the jury. Further, the evidence is sufficient to

sustain the jury’s finding that Rucker was responsible for 70% of

the negligence that resulted in his injuries, thereby precluding

any obligation for Euclid to compensate him for his damages. 

VII. JURY CHARGE

a. Euclid’s challenge to the jury charge on the issue of causation

Concerning the causation element of Plaintiffs’ negligence

cause of action, the district court instructed the jury that

“[P]roximate cause” means that cause which in a natural

and continuous sequence, unbroken by any new and

independent cause, produces an event without which that

event would not have occurred, and which event or some

similar event should have been foreseen by a person in

the exercise of ordinary care under the same or similar

circumstances . . . .

The district court separately defined the causation element of

the Plaintiffs’ products liability cause of action:

“[P]roducing cause” as used in these instructions, means

an efficient, exciting, or contributing cause, which in

a natural and continuous sequence, produces the injury in

question . . . . 

Euclid complains that the district court did not accept its

proposed jury instruction that in order to impose liability on
31

negligence or products liability claims, the jury must determine

that Euclid’s conduct was a substantial factor and a “but for”

cause of the plaintiffs’ injuries, citing Texarkana Memorial Hosp.,

Inc. v. Murdock, 946 S.W.2d 836 (Tex. 1997) and Gutierrez v. Excel

Corp., 106 F.3d 683, 687 (5th Cir. 1997). 

This court has stated the standard of review for jury charge

challenges:

First, the challenges must demonstrate that the charge as

a whole creates substantial and ineradicable doubt

whether the jury has been properly guided in its

deliberations. Second, even if the jury instructions

were erroneous, we will not reverse if we determine,

based upon the entire record, that the challenged

instruction could not have affected the outcome of the

case. If the party wishes to complain on appeal of the

district court’s refusal to give a proffered instruction,

that party must show as a threshold matter that the

proposed instruction correctly stated the law.

Flores v. Cameron County, Tex., 92 F.3d 258, 262 (5th Cir.

1996)(internal quotation marks omitted).

Euclid complains that the jury charge did not adequately

inform the jury that because the injuries claimed by the plaintiffs

do not arise from any discrete event, the plaintiffs bear the

burden of showing that the defect or negligence actually caused the

injuries. We are not convinced that the charge as a whole, which

employed language identical to the definitions provided in the

Texas Pattern Jury Charges, creates substantial and ineradicable

doubt whether the jury has been properly guided in its

deliberations. We therefore will not disturb the verdict based on
32

Euclid’s challenge to the jury instructions on causation.

b. Rucker’s challenge to the jury charge

Rucker contends on cross-appeal that the district court abused

its discretion by refusing to grant his request that the jury be

instructed on the effect of its answers regarding proportional

responsibility. Unlike Texas state courts, federal courts are free

to tell juries the effect of their answers. See Martin v. Texaco,

Inc., 726 F.2d 207, 216 (5th Cir. 1985). The decision whether to

instruct the jury on the effects of its answers is “a matter of

discretion for the trial court.” Martin v. Texaco, Inc., 726 F.2d

207, 216 (5th Cir. 1984). 

Rucker further complains that the trial court refused his

requested special instruction that “a plaintiff’s negligence, if

any, in merely failing to discover a product defect or guard

against the possibility of its existence cannot form the basis of

an affirmative finding against a plaintiff on the issue of

negligence.” Rucker takes the position that the omission of these

two instructions led to an incomplete and erroneous charge on

Euclid’s proportionate responsibility defense and affected the

outcome of Rucker’s case. Rucker alleges that, taken together,

these two jury charge decisions by the district court amounted to

error in the jury instructions that prejudiced the outcome of the

case. See Aero Int’l, Inc. v. United States Fire Ins. Co., 713

F.2d 1106, 1113 (5th Cir. 1983).
33

In Perricone v. Kansas City Southern Rwy. Co., 704 F.2d 1376

(5th Cir. 1983), the district court gave a supplemental instruction

which informed the jury that the Plaintiff would not recover any

damages if the Plaintiff was found to be more than 50% negligent.

This Court affirmed the giving of the supplemental instruction in

the absence of contemporaneous objection. Id. at 1377. However,

Perricone does not mandate the giving of such instructions. We

find that the failure of the district court to instruct the jury on

the effect of its answers concerning the Plaintiffs’ proportionate

responsibility in this case does not call into question the jury’s

factual determination that Plaintiffs were negligence and that

their negligence was a producing cause of their injuries. 

In a strict liability cause of action, a plaintiff’s failure

to discover or guard against a product’s defect is not a defense to

a defendant’s liability. See Keen v. Ashot Ashkelon, 748 S.W.2d 91

(Tex. 1988). Therefore, Rucker’s requested charge was a correct

statement of the law in that regard. However, we are not left with

substantial or eradicable doubt that the jury was properly guided

in its deliberations. See Flores, 92 F.3d at 262. Both Plaintiffs

and Euclid developed through evidence and argument before the jury

their theories concerning proportionate responsibility of the

Plaintiffs. We will not reverse the verdict because, based on the

entire record, we do not conclude that the requested instructions

would have affected the outcome of the case. Id. 
34

VIII. CONCLUSION

Based on the foregoing, we affirm the district court’s

judgment.

AFFIRMED.
35

DeMOSS, Circuit Judge, dissenting:

I respectfully dissent. The plaintiffs in this case did not

produce evidence that sufficiently demonstrates a causative link

between their alleged injuries and Euclid’s short-nose coal

haulers. The district court abused its discretion by lowering the

Daubert standard for admitting expert opinion testimony which was

neither relevant nor reliable. Finally, this case should have been

dismissed as time-barred because the plaintiffs’ claims of injury,

based on one doctor’s subjective evaluation of MRIs, are not

objectively verifiable as required under Texas case law governing

the tolling of the statute of limitations pursuant to the discovery

rule.

I.

Euclid, Inc., designs and manufactures 120-ton coal-hauling

vehicles used at open pit coal mines. Before the mid-1970s, Euclid

used a “long-nose” design. Like a pick-up truck, this design put

the engine at the front, with the cab above and behind. Then,

responding to consumer demands for greater driver visibility and

maneuverability, Euclid and its competitors switched to “shortnose” designs. The new designs placed the driver in front, with

the engine below and behind. This gives the front of the vehicle
-36-

a flat, snub-nosed appearance. Euclid’s design changes included

other modifications, including a shorter wheel base, a trailing arm

suspension, and rubber struts instead of steel springs.

When the short-nosed design was introduced in the mid-1970s,

Euclid sold several vehicles to Texas Utilities Mining Company

(TUMCO). The five original plaintiffs in this case, males ranging

in age from 32 to 46, are former TUMCO employees. They all

operated the Euclid 322 NDT short-nose coal hauler. In addition,

the plaintiffs also operated other heavy machinery in the coal pit,

including bulldozers, scrapers, water trucks, and end-dump trucks.

The plaintiffs allege that they have suffered back injuries

which resulted from “repetitious trauma and severe vibrations”

experienced while operating the Euclid short-nose coal hauler.

They sued Euclid, claiming that their back conditions were due to

the Euclid short-nose coal hauler’s defective design, which

rendered the product unreasonably dangerous (the strict products

liability claim), and Euclid’s negligent design, marketing, and

failure to warn customers and operators about safety risks

pertaining to the short-nose coal hauler (negligence and gross

negligence claims). Their suit was filed in the Eastern District

of Texas, Marshall Division.

The sufficiency and admissibility of the testimony offered by

the plaintiffs’ expert witnesses lies at the heart of the

controversy in this appeal. The plaintiffs’ five testifying
-37-

experts have been divided by the panel majority into two categories

-- two engineer “liability” experts who testified about the shortnose coal hauler and three medical “causation” experts who

testified about the plaintiffs’ injuries. Euclid sought summary

judgment based on its contention that the plaintiffs’ proposed

expert testimony, necessary to establish causation and liability,

could not be admitted pursuant to Fed. R. Evid. 702 and Daubert v.

Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S. Ct. 2786

(1993). Euclid’s Daubert argument was rejected by the district

court, but a continuing objection to identified expert testimony

was permitted. Euclid also raised a limitations defense, but the

district court determined that the discovery rule would apply.

Ultimately, a jury rendered a $2.8 million verdict against

Euclid. Euclid moved for judgment as a matter of law (JMOL) on the

question of liability, all plaintiffs sought JMOL on Euclid’s

contributory negligence arguments, and plaintiff Tim Rucker, who

received a take-nothing judgment because of the jury’s

determination that he was 70% contributorily negligent, moved for

a new trial. These post-trial motions were denied. All parties

timely appealed.

II.

A detailed discussion of the expert testimony offered at trial

by the plaintiffs is necessary to the ensuing substantive
12 Euclid vigorously contests the probity of conclusions based on

testing of a single hauler in Australia almost 20 years ago.

Euclid contends that the haulers sent to Australia were specially

modified to the customer’s specifications. The company has also

conceded that the hauler sent to Australia may have been a lemon.

-38-

discussions. As previously mentioned, the experts fall into two

general categories -- engineers who testified about the design and

quality of ride of the short-nose coal hauler (“liability

experts”), and doctors who testified about the plaintiffs’ physical

condition (“causation experts”).

A.

The liability experts testified about Euclid’s coal haulers.

Mr. Geoff McDonald is an Australian engineer who had experience

with the Euclid short-nose coal hauler dating back to 1977.

Workers asked to operate a problematic Euclid short-nose coal

hauler at the Blackwater Mine in Australia refused to operate it

because its ride was so rough.12 Mr. McDonald was asked to test the

short-nose coal hauler at that time, and based on his testing in

Australia, he testified that the long-nose haulers are safer

because they are four to five times less likely to cause injury

than the short-nose haulers.

Mr. Arthur Chaseling is a consulting mechanical engineer who

also testified that he thought the long-nose design was safer. In

1996, Mr. Chaseling traveled with Mr. McDonald to Texas to test

TUMCO’s short-nose coal haulers. Mr. McDonald testified that the
13 The ISO standards are not binding on Euclid, and Euclid

contests the probity of using these standards.

14 Plaintiff Johnny W. Bartley testified:

[T]here were several jobs that a hauler operator would

-39-

mine operations and physical layout were similar to those at the

Blackwater mine. Messrs. Chaseling and McDonald together measured

the vibrations experienced by TUMCO’s employees who operated the

Euclid short-nose coal hauler. These tests were conducted by

attaching an accelerometer to the metal frame below the seat of a

Euclid coal hauler. Using these measurements, Mr. Chaseling

determined that the Euclid short-nose coal hauler’s vibrations

exceed the health and safety limits of the International Standards

Organization (ISO).13 Messrs. Chaseling and McDonald did not test

any of the other earth-moving equipment operated at the mine to

measure their vibrations, and they did not attempt any sort of

comparison between the short-nose coal hauler and the other

machines operated by the plaintiffs.

B.

The key causation expert was Dr. Charles N. Aprill, a medical

doctor specializing in diagnostic radiology. He performed MRIs on

the backs of approximately ninety TUMCO employees, including the

plaintiffs, who operated the Euclid short-nose coal hauler. These

employees also operated other heavy machinery such as scrapers,

bulldozers, water trucks, and end-dump trucks,14 but Dr. Aprill’s
perform in hauler operator classification, of course, one

being operate the hauler, another being to run the crusher,

run the water truck and assorted pump duties, the

dewatering type job whereupon rains you would pump water

out of the pit to help dry it up. You were kind of a doall individual.

All the other plaintiffs except Mike R. Rucker testified that they

operated the same machines described by Mr. Bartley, as well as a

bulldozer. Mr. Rucker had only begun driving the coal hauler for

TUMCO in late 1990 or early 1991, and he testified that in addition

to the coal hauler he also operated the water truck, end-dump

truck, and a backhoe. During previous employment, Mr. Rucker had

been a manual laborer, had operated other heavy machinery, such as

a forklift, and had injured his back on the job.

-40-

tests did not indicate that he had considered the effect of, or

differentiated among the TUMCO employees based on, their length of

employment or the amount of time they spent operating particular

machines. He compared the results of these MRIs with a “control

group” of MRIs performed on a group of “consecutive patients who

were scanned roughly during the time these [TUMCO] patients were

scanned, who were referred because they had some sort of back

problem.” The control group patients were selected to be age- and

gender-matched to the test group of ninety TUMCO employees, but the

control group did not include anyone who operated coal haulers or

any other kind of earth-moving equipment. 

Dr. Aprill found “endplate infractions” -- impact craters

which form in an intervertebral disc when a load is applied to it

-- in 90% of the TUMCO employees and in 68% of the “control group”

of other back pain patients being treated by Dr. Aprill. He also

found that while the endplate infractions occurring in the general
-41-

back-pain population clustered between the lower dorsal spine and

the upper lumbar spine, the TUMCO employees exhibited endplate

infractions in that area as well as throughout the lumbar spine.

According to Dr. Aprill, these endplate infractions render one more

susceptible to back injury. Dr. Aprill concluded that the

“repeated vertical compression” experienced by the TUMCO employees

caused the endplate infractions.

On cross-examination, Dr. Aprill opined that for “the normal

population without any occupational stresses,” the incidence of

endplate infractions is “something in the order of forty percent or

so,” and that “any person that’s subjected to repetitive

compression, whatever the source, is likely to develop changes

similar to what we saw.” Dr. Aprill stated that he had not

compared the MRIs of the backs of short-nose coal hauler operators

to test results for the operators of any other type of coal hauler;

neither had he compared the MRIs of short-nose coal hauler

operators to those of workers who operated bulldozers, end-dump

trucks, scrapers, water trucks, or tractors. He further stated

that he could not testify about the effect of operating those kinds

of heavy equipment because he had “not seen MRI scans on large

numbers of other heavy equipment operators.” When challenged about

his conclusions that the plaintiffs’ endplate infractions were

caused by the vibrations of the Euclid short-nose coal hauler, Dr.

Aprill conceded that he could not point to any study which might

indicate how much vibration was necessary to produce the injuries
-42-

he identified. His method and findings had not been reviewed by a

statistician or an epidemiologist or submitted for peer review and

publication, and no rate of error had been calculated for his

theory. Furthermore, he had not conducted any prior research or

studies -- nor had he submitted any papers or published any

articles -- on vibration and its effects on the back.

Dr. Richard W. Bunch is a ergonomics consultant and physical

therapist who rode in a Euclid short-nose coal hauler. Dr. Bunch

used a pen and a pad of paper to keep track of the jerks and jolts

that he felt during the ride. Based on his conclusions from this

“semi-objective” field experiment, he testified that the vibrations

experienced by the plaintiffs when they operated the Euclid shortnose coal hauler contributed to their injuries and that the design

of the cab was not sufficient to protect the operator from the

vibrations. Dr. Bunch’s test was not subjected to peer review.

Dr. Kelvin A. Samaratunga is a neurosurgeon and a clinician

who evaluates and treats back pain. He reviewed all of the

previously described expert testimony, and he rode on a Euclid

short-nose coal hauler. In particular, he reviewed the plaintiffs’

medical records and MRIs. He testified that he agreed with Dr.

Aprill that the endplate infractions were the result of whole body

vibration, and that they would eventually lead to back problems for

the plaintiffs. On cross-examination, Dr. Samaratunga conceded

that he was not an expert on vibration and he had not performed any

studies or published any materials in that field of study. He is
-43-

not an epidemiologist or a statistician either. When asked, Dr.

Samaratunga indicated that he could not identify any published

study which indicated that the levels of vibration measured in the

short-nose coal haulers could cause the injuries of which the

plaintiffs complained. The materials reviewed by Dr. Samaratunga

did not address the effect, if any, of the other equipment operated

in the mines by the plaintiffs.

III.

Euclid unsuccessfully moved for judgment as a matter of law

based on the insufficiency of the evidence to establish a causative

link between the plaintiffs’ injuries and their operation of the

Euclid short-nose coal hauler. De novo review applies, with

inferences drawn in favor of the nonmoving party. See Gutierrez v.

Excel Corp., 106 F.3d 683, 686 (5th Cir. 1997).

A.

Texas law provides the substantive rule of what the plaintiffs

were required to establish in order to prove Euclid’s liability.

The landmark decision of Erie Railroad Co. v. Tompkins, 304 U.S.

64, 58 S. Ct. 817 (1938), established that “[e]xcept in matters

governed by the Federal Constitution or by Acts of Congress, the

law to be applied in any case is the law of the State.” 304 U.S.

at 78, 58 S. Ct. at 822. Generally speaking, federal courts
-44-

sitting in diversity apply the substantive law of the state

providing the law of decision, while following federal procedural

law. See, e.g., Gasperini v. Center for Humanities, Inc., 518 U.S.

415, 116 S. Ct. 2211, 2219 (1996). When the difference between

applying state law and federal law is outcome-determinative, that

factor is a strong indicator that the federal court should apply

state law. See id. at 426-28, 116 S. Ct. at 2219-20; Guaranty

Trust Co. v. York, 326 U.S. 99, 65 S. Ct. 1464 (1945). The test of

outcome determination cannot, however, be applied mechanically; a

federal court must instead be guided by “the twin aims of the Erie

rule: discouragement of forum-shopping and avoidance of inequitable

administration of the laws.” Gasperini, 518 U.S. at 428, 116 S.

Ct. at 2220 (quoting Hanna v. Plummer, 380 U.S. 460, 468, 85 S. Ct.

1136, 1142 (1965)).

Consistent with these principles, it is well established that

in diversity cases, state law determines the quality and quantum of

evidence that must be produced to establish a cause of action,

while the standard for reviewing the sufficiency of evidence to

sustain a jury verdict on appeal is indisputably governed by a

federal standard. See, e.g., Jones v. Wal-Mart Stores, Inc., 870

F.2d 982, 986 (5th Cir. 1989); Tutor v. Ranger Ins. Co., 804 F.2d

1395, 1398 (5th Cir. 1986); Ayers v. Sears, Roebuck & Co., 789 F.2d

1173, 1175 (5th Cir. 1986); McCandless v. Beech Aircraft Corp., 779

F.2d 220, 223 (5th Cir. 1985); Fairley v. American Hoist & Derrick
-45-

Co., 640 F.2d 679, 681 (5th Cir. Unit A 1981). Federal law thus

mandates that we review the jury’s verdict by the same standard as

the district court, affirming unless “there is no legally

sufficient evidentiary basis for a reasonable jury to find” as the

jury did. Fed. R. Civ. P. 50(a)(1); see Denton v. Morgan, 136 F.3d

1038, 1044 (5th Cir. 1998). The Erie doctrine, however, mandates

that the object of this inquiry be whether the evidence adduced by

the plaintiffs adequately establishes a prima facie case according

to the laws of the state of Texas, such that the jury verdict may

be approved.

This result is necessary both to discourage forum-shopping and

to ensure the equitable administration of the laws. Were we to

apply some lower standard -- essentially lowering the burden of

proof -- products liability and negligence plaintiffs would have a

considerable incentive to file suit in federal court rather than in

state court because it would be easier for them to win a case.

That is precisely what the Erie doctrine seeks to prevent. In this

case, we must therefore consider whether the plaintiffs have

proved, as a matter of Texas law, that their injuries were caused

by the Euclid short-nose coal hauler.

B.

Under Texas law, causation in fact is an element of the both

the plaintiffs’ strict products liability claims and their
15 As the Texas Supreme Court neatly summarized:

Negligence requires a showing of proximate cause, while

producing cause is the test in strict liability. Proximate

and producing cause differ in that foreseeability is an

element of proximate cause, but not of producing cause.

Proximate cause consists of both cause in fact and

foreseeability. Cause in fact means that the defendant’s

act or omission was a substantial factor in bringing about

the injury which would not otherwise have occurred. A

producing cause is “an efficient, exciting, or contributing

cause, which in a natural sequence, produced injuries or

damages complained of, if any.” Common to both proximate

and producing cause is causation in fact, including the

requirement that the defendant’s conduct or product be a

substantial factor in bringing about the plaintiff’s

injuries.

Union Pump Co., 898 S.W.2d 773, 775 (Tex. 1995) (emphasis supplied,

citations omitted).

-46-

negligence claims. See, e.g., Union Pump Co. v. Allbritton, 898

S.W.2d 773, 775 (Tex. 1995).15 In order to establish this element,

common to all their various claims that Euclid engaged in tortious

activity, the plaintiffs must prove that vibrations produced by the

short-nose coal hauler constituted “a substantial factor in

bringing about the injury and without which no harm would have

occurred.” E.g., Havner v. E-Z Mart Stores, Inc., 825 S.W.2d 456,

458-59 (Tex. 1992) (emphasis supplied); Nixon v. Mr. Property

Management Co., 690 S.W.2d 546, 549 (Tex. 1985) (emphasis

supplied); see also Restatement (Third) of Torts: Products

Liability § 15 (1997) (hereinafter Restatement (Third)) (“Whether

a product defect caused harm to persons or property is determined

by the prevailing rules and principles governing causation in
16 Strictly speaking, the “substantial factor” inquiry is

probative only in the event that “two causes concur to bring about

an event, and either one of them operating alone, would have been

sufficient to cause the identical result.” Prosser & Keeton,

supra, § 41, at 266. The plaintiffs have not argued that the

Euclid short-nose coal hauler is one of several factors which would

have independently caused their injuries, so we need not consider

whether these facts fall into that special subset of cases.

-47-

tort.”). By requiring that the allegedly tortious activity be a

factor “without which no harm would have occurred,” the test

embodies, as one of its elements, the “traditional ‘but-for’ rule

of causation.” 1 J. Hadley Edgar, Jr. & James B. Sales, Texas

Torts and Remedies § 1.05[2][a], at 1-111 (1998); see also W. Page

Keeton et al., Prosser and Keeton on Torts § 41, at 266 (5th ed.

1984) (hereinafter, Prosser & Keeton) (“Restricted to the question

of causation alone, and regarded merely as a rule of exclusion, the

‘but-for’ rule serves to explain the greatest number of

cases . . . .”); David W. Robertson, The Common Sense of Cause in

Fact, 75 Texas L. Rev. 1765, 1768 (1997) (noting that the but-for

standard is the “most widely accepted test” for determining cause

in fact); Restatement (Third), supra, § 15. That being the case,

Texas law requires that the plaintiffs prove but-for causation with

respect to the alleged injurious effect of the short-nose coal

hauler; it is not sufficient for the plaintiffs to merely present

evidence that the vibrations produced by the short-nose coal hauler

constituted a “substantial factor” in producing the plaintiffs’

injuries.16
-48-

C.

A five-step logical process provides a careful (if tedious)

model for determining whether a given event is a cause in fact of

a plaintiff’s injuries. In summary, the five logical steps for

proving but-for causation are as follows:

(a) identify the injuries in suit; (b) identify the

wrongful conduct; (c) mentally correct the wrongful

conduct to the extent necessary to make it lawful,

leaving everything else the same; (d) ask whether

the injuries would still have occurred had the

defendant been acting correctly in that sense; and

(e) answer the question.

Robertson, supra, at 1771. The application of this framework of

analysis will help to locate any logical flaw which may taint the

plaintiffs’ theory of causation.

The first step is to identify the plaintiffs’ injuries. In

this case, the plaintiffs have alleged that they have suffered

endplate infractions in their spines which render them more

susceptible to serious back pain in the future. The second step is

to name the defendant’s allegedly wrongful conduct. Because there

are multiple answers at this second step relating to each of the

plaintiffs’ theories of liability, we must consider each theory

separately.
17 “In Texas, section 402A of the Restatement (Second) of Torts

governs claims for strict liability in tort.” American Tobacco Co.

v. Grinnell, 951 S.W.2d 420, 426 (Tex. 1997) (citing Firestone

Steel Prods. Co. v. Barajas, 927 S.W.2d 608, 613 (Tex. 1996);

McKisson v. Sales Affiliates, Inc., 416 S.W.2d 787, 788-89 (Tex.

1967)). According to that rule:

(1) one who sells any product in a defective condition

unreasonably dangerous to the user or consumer or to his

property is subject to liability for physical harm thereby

caused to the ultimate user or consumer, or to his

property, if

(a) the seller is engaged in the business of selling such

a product, and

-49-

1.

The plaintiffs have a strict products liability claim and a

negligence claim based on defective design. The allegedly wrongful

conduct for the purposes of both of these claims was negligent

design of the short-nose coal hauler pursuant to Euclid’s business

decisions to stop manufacturing long-nose coal haulers and to begin

manufacturing short-nose coal haulers. Because these separate

claims focus on the same activity, they may be grouped for the

purpose of determining whether that activity was a cause in fact of

the plaintiffs’ injuries.

Taking the third analytical step with respect to these claims,

we must hypothesize a scenario that would erase the effect of the

allegedly wrongful conduct. According to the plaintiffs’ theory of

their products liability case, the short-nose coal hauler subjects

its operator to harmful vibration, rendering the machine defective

and unreasonably dangerous.17 Similarly, in the negligence rather
(b) it is expected to and does reach the user or consumer

without substantial change in the condition in which it is

sold.

Restatement (Second) of Torts § 402A (1965). “A product may be

unreasonably dangerous because of a defect in marketing, design, or

manufacturing.” Grinnell, 951 S.W.2d at 426.

-50-

than strict liability context, the plaintiffs additionally contend

that the Euclid acted negligently in designing the short-nose

hauler, such that the machine’s operators were subjected to harmful

vibrations, thus resulting in injury. In order to overcome the

argument that the balance between “the utility of the product and

the risk involved in its use” precludes liability on these

theories, see, e.g., American Tobacco Co. v. Grinnell, 951 S.W.2d

420, 432 (Tex. 1997), the plaintiffs pointed to the older long-nose

coal hauler as a safer alternative design which, they contend, did

not suffer from the same defect.

For the purpose of these design-based theories, then, the

third step of the analysis would be accomplished by trading the

short-nose coal haulers for Euclid’s older long-nose coal hauler

models. The inquiry would then be completed by determining, at the

fourth step, whether the plaintiffs’ injuries would have occurred

if they drove long-nose coal haulers and not short-nose coal

haulers. If not, taking the fifth and final logical step, cause in

fact has been established.
-51-

2.

Regarding the plaintiffs’ remaining negligence and gross

negligence claims, the allegedly wrongful conduct was a marketing

defect, namely, Euclid’s failure to warn customers and operators

about safety risks arising from vibration in the short-nose coal

hauler. The plaintiffs contend that such warnings would have

allowed them to minimize their exposure to vibration and repetitive

trauma while operating the short-nose coal hauler.

Removing the effect of the wrongful conduct to take the third

logical step in this scenario, one must hypothesize a work

environment in which TUMCO and its employees were warned about

safety risks arising from the short-nose coal hauler’s tendency to

vibrate. One would therefore assume that precautions were taken to

reduce or eliminate the exposure to vibration, either by TUMCO’s

refusal to buy Euclid’s short-nose coal hauler, the plaintiffs’

refusal to operate the machine, or perhaps some sort of

prophylactic precaution such as a modification of the machine

itself or of the employees’ usage of the machine. Given this

scenario, the fourth step leads to the question of whether the

plaintiffs would have been injured in a work environment exactly

the same as it actually was except that they were not exposed to

unsafe vibrations in the short-nose coal hauler. If it can be

proved that there would have been no injury in this scenario, cause
-52-

in fact will have been established for the plaintiffs’ negligence

claim against Euclid.

3.

Based on the above reasoning, the key logical step in both

scenarios is the fourth step designated above, specifically,

“whether the injuries that the plaintiff[s] suffered would probably

still have occurred had the defendant behaved correctly in the

sense indicated.” Robertson, supra, at 1771. It is apparent that

in order to establish Euclid’s liability on theories of strict

products liability or negligence, the plaintiffs were required to

present evidence to prove one of the two factual causation

scenarios. They could show either that similarly situated workers

who operated long-nose coal haulers but not short-nose coal haulers

would not experience the injuries experienced by the plaintiffs

(products liability and design defect claims), or that similarly

situated workers who operated all the machines operated by the

plaintiffs except the short-nose coal hauler would not experience

the injuries experienced by the plaintiffs (marketing defect or

failure-to-warn claims). I now turn to those absolutely necessary

links of causation.
-53-

D.
-54-

Our guiding star in considering whether the plaintiffs have

adequately established causation to justify imposing liability upon

Euclid should be the recent treatment of tort causation by the

Supreme Court of Texas in Merrell Dow Pharmaceuticals, Inc. v.

Havner, 953 S.W.2d 706 (Tex. 1997) (hereinafter, Havner).

In that case the court reversed a jury verdict in favor of

plaintiffs who had claimed that use of the drug Bendectin caused a

birth defect in their child. The central issue throughout the

litigation was the reliability of the expert testimony offered to

establish causation. Though the specific issue before the court

was whether the Havners’ evidence was scientifically reliable and

constituted “some evidence” to support the plaintiffs’ judgment,

the circumstances of the case led the court to consider precisely

what a plaintiff must establish to raise a fact issue of whether a

drug caused an individual’s birth defect. This prompted a

discussion of some very fundamental issues relating to proving

causation.

The court noted that causation in toxic tort cases can be

discussed in terms of either general or specific causation:

General causation is whether a substance is capable

of causing a particular injury or condition in the

general population, while specific causation is

whether a substance caused a particular

individual’s injury. In some cases, controlled
-55-

scientific experiments can be carried out to

determine if a substance is capable of causing a

particular injury or condition, and there will be

objective criteria by which it can be determined

with reasonable certainty that a particular

individual’s injury was caused by exposure to a

given substance.

Havner, 953 S.W.2d at 714-15. In many toxic tort cases, however,

direct experimentation cannot be done. As a result, there can be

no reliable, direct evidence of specific causation. The court thus

reasoned:

In the absence of direct, scientifically

reliable proof of causation, claimants may attempt

to demonstrate that exposure to the substance at

issue increases the risk of their particular

injury. The finder of fact is asked to infer that

because the risk is demonstrably greater in the

general population due to exposure to the

substance, the claimant’s injury was more likely

than not caused by that substance. Such a theory

concedes that science cannot tell us what caused a

particular plaintiff’s injury. It is based instead

on a policy determination that when the incidence
-56-

of a disease or injury is sufficiently elevated due

to exposure to a substance, someone who was exposed

to that substance and exhibits the disease or

injury can raise a fact question on causation.

Id. at 715 (emphasis supplied) (citing Daubert v. Merrell Dow

Pharms., Inc., 43 F.3d 1311, 1320 n.13 (9th Cir. 1995) (on remand

from the Supreme Court)).

While Havner dealt with causation principles in the context of

a toxic tort case, the underlying issues are compellingly similar

to the problems of proving that the Euclid short-nose coal hauler

caused the plaintiffs’ injuries in this case. First, the

plaintiffs in Havner, just like the plaintiffs in the instant case,

brought a products liability suit based on theories of negligence,

defective design, and defective marketing. Second, the Havners did

not contend that all limb reduction birth defects are caused by

Bendectin, and, likewise, the plaintiffs before us in this appeal

recognize that not all endplate infractions are caused by driving

Euclid’s short-nose coal hauler. Finally, in Havner, as here, the

only proof of causation offered by the plaintiffs was scientific

expert testimony relating the results of studies on the association

between the use of a product and certain injuries which allegedly

resulted from that use.
-57-

The plaintiffs and the panel majority would prefer that this

case be treated differently than Havner, asserting that the present

litigation is nothing like the infamous Bendectin cases. Quite to

the contrary, this case bears many similarities to that

significant, trend-setting series of cases. An underlying premise

in many toxic tort cases is that the plaintiff has suffered an

injury, such as cancer, which may have occurred even if the

plaintiff had not been exposed to the substance at issue. So too

in this case, the plaintiffs claim that they have suffered an

injury, endplate infractions, which may have occurred even if they

had never operated the short-nose hauler. Furthermore, and very

significantly, just as toxic tort causation (as a practical matter)

usually cannot be established by exposing human subjects to the

substance in question for testing purposes, direct experimentation

cannot be done (or at least has not been done) to prove objectively

that use of the short-nose coal hauler causes endplate infractions,

and these plaintiffs are therefore left to attempt to prove their

case using epidemiological (or, in this case, pseudoepidemiological) studies. In these respects, the case sub judice

is much more akin to a toxic tort case than a traditional personal

injury case, and as such, we should not shy away from considering

Texas law regarding toxic torts.

Because causation cannot be proved directly by the plaintiffs,

the only remaining avenue available in tort law for the purpose of
18 Of course, Havner does not purport to require that, and we

need not consider whether, epidemiological standards must be used

be used to indirectly prove tort causation with scientific medical

opinion testimony. It is certainly worthy of note, however, that

this Court has previously stated: “While we do not hold that

epidemiologic proof is a necessary element in all toxic tort cases,

it is certainly a very important element.” Brock v. Merrell Dow

Pharms., Inc., 874 F.2d 307, 313 (5th Cir. 1989).

-58-

proving causation is to demonstrate that their use of the shortnose coal hauler increased their risk of injury. In order to

determine causation in these circumstances, the finder of fact must

be guided by the “more likely than not” burden of proof.

Havner established as a matter of Texas law that the more

likely than not burden of proof requires, in order to be probative

of causation, that epidemiological studies must demonstrate more

than a doubling of the risk of injury.18 The supreme court

explained:

Although we recognize that there is not a

precise fit between science and legal burdens of

proof, we are persuaded that properly designed and

executed epidemiological studies may be part of the

evidence supporting causation in a toxic tort case

and that there is a rational basis for relating the

requirement that there be more than a “doubling of

the risk” . . . to the more likely than not burden

of proof.
-59-

Havner, 953 S.W.2d at 717. This same standard of causation applies

to the scientific evidence adduced by the plaintiffs in this case.

Even though the studies conducted by the plaintiffs’ experts are

not “epidemiological studies,” the plaintiffs’ studies seek to

accomplish the same objective as an epidemiological study -- they

attempt to explain the cause of the endplate infractions which

their MRI studies show that the plaintiffs experienced. Indeed,

the only reason why the plaintiffs’ experts’ studies are not

epidemiological studies is because they were not conducted

according to well-established standards for reliably conducting

epidemiological inquiries.

A scientific study providing indirect scientific evidence of

tort causation, standing alone, is not sufficiently probative of

legal causation if it does not tend to show that the suspected

cause is more likely than not the actual cause of an injury. In

other words, such a study is not probative of causation if it fails

to demonstrate that the suspected cause doubles the risk of injury

as compared to the general population which was not exposed or

subjected to the suspected cause.
-60-

E.
19 For reasons explained later, the expert opinions were not

admissible. See infra Part IV.

20 The panel majority refers to Minnesota Mining & Manufacturing

Co. v. Atterbury, No. 06-97-00099-CV (Tex. App.--Texarkana July 31,

1998, n.p.h.) (not designated for publication), 1998 WL 436916

(hereinafter, 3M), for the propositions that there is “no

requirement that a party must have reliable epidemiological

evidence of a relative risk of 2.0 or greater” and that “[r]eliable

evidence of relative risk less than 2.0 can be considered, but must

be supported by other credible, reliable evidence of causation.”

Majority Op. at Part IV(c) (citing 3M, 1998 WL 436916, at *15). It

is certainly true that the court in Havner did not impose a

requirement that epidemiological evidence be used to prove

causation, but that does not mean that epidemiological evidence

that does not show a doubling of the risk may be used or that such

evidence will support a jury’s verdict.

The 3M Court relied on Pick v. American Medical Sys., Inc., 958

F. Supp. 1151 (E.D. La. 1997), for the proposition that

“epidemiological evidence with a relative risk lower than 2.0

should be considered because . . . it is relevant evidence.” 3M,

1998 WL 436916, at *15. Several things should be noted about the

-61-

Assuming, arguendo, the admissibility of the plaintiffs’

experts’ testimony,19 the evidence of causation is insufficient to

support a verdict of negligence or strict liability. The key flaw

in the plaintiffs’ evidence is that it fails to show that the

plaintiffs’ common injuries and exposure to the Euclid short-nose

coal hauler are anything more than a coincidence.

Dr. Aprill’s “study” revealed endplate infractions in 90% of

the TUMCO employees and 68% of the “control group” of back pain

patients. Based on this statistical comparison, it is apparent

that any given back-pain patient most likely would have had the

infractions even though he had not operated a Euclid short-nose

hauler.20 Likewise, it is apparent that the risk of endplate
Pick opinion. First, Pick is the opinion of a federal district

court in Louisiana, applying Louisiana law to a products liability

and negligence case arising from a claim that Mr. Pick’s penile

implant, designed and manufactured by the defendant, caused Mr.

Pick to suffer from various health disorders which led to his

eventual death. Our task in deciding diversity cases is to apply

state law in the same fashion as we can best discern that the state

supreme court would apply it. Although in deciding 3M the

Texarkana Court of Appeals relied on a decision of the United

States District Court for the Eastern District of Louisiana, Pick,

to inform its interpretation of an opinion of the Supreme Court of

Texas, Havner, I am not persuaded that the Supreme Court of Texas

would follow the same path. Second, Pick refers only to the

admissibility of epidemiological evidence of relative risk above

1.0, not whether such evidence will support a jury verdict imposing

liability. See Pick, 958 F. Supp. at 1160. In fact, the court in

Pick granted summary judgment for the defendant based on the

inadequacy of the plaintiffs’ evidence to prove causation, and the

plaintiffs’ evidence in that case was not limited to

epidemiological evidence. See id. at 1173.

-62-

infractions in the TUMCO employee test group is not more than twice

the risk of endplate infractions in the control group. Plainly

then, the statistics produced by the study do not tend to establish

the plaintiffs’ case. Cf. Havner, 953 S.W.2d at 717.

Moving beyond the statistical findings, however, the majority

primarily rests its conclusions upon the so-called “fingerprint” of

injury characteristics exposed by Dr. Aprill’s subjective

interpretation of the number and physical distribution throughout

the spine of endplate infractions as exhibited in the plaintiffs’

MRIs. Unfortunately, this “fingerprint” evidence is completely

irrelevant because it bears absolutely no relation whatsoever to

the links of causation that the plaintiffs are obligated to

demonstrate. The “fingerprints” give us no guidance as to whether
21 Experts for Euclid, on the other hand, did test the other

machines and found that, assuming that the vibration of these

machines was a concern at all, other machines such as the bulldozer

and the scraper presented a much greater concern for the operators

than did the short-nose coal hauler. For the apparent purpose of

demonstrating to the jury that the vibrations were not a serious

concern, Euclid’s experts also compared the short-nose coal

hauler’s vibrations to those generated by a Corvette and a Suburban

driven around the courthouse square.

-63-

the injuries would have occurred if the plaintiffs had operated

long-nose coal haulers rather than short-nose coal haulers.

Neither do the “fingerprints” demonstrate that the injuries would

not have occurred absent exposure to the short-nose coal hauler.

There is no proof that the level of vibration produced by the

short-nose coal hauler was in any respect significantly different

from the level of vibration generated by other heavy earth-moving

equipment operated by the plaintiffs.21 In fact, Dr. Aprill

conceded that he could not distinguish, based on his study, which

of the many pieces of heavy machinery operated by the coal haulers

might have been the cause of the endplate infractions. That is so,

at least in part, because the study made no attempt to

differentiate among its subjects based on their work histories,

including what types of equipment the TUMCO employees had operated,

and for what periods of time they operated that equipment. Dr.

Aprill had no way to eliminate from his study the effects of other

sources of vibration.

As explained earlier, see supra Part III(B), one of the above

mentioned factual scenarios had to be established as a factual
22 An alternative, more formal logical explanation for the

problem presented by this case may be that Dr. Aprill’s reasoning

suffers from the “fallacy of post-hoc statistics,” which occurs

when “[d]ifferences that are discovered by accident then become the

verification of an ad-hoc hypothesis that was the result of the

observation.” Kenneth R. Foster & Peter W. Huber, Judging Science:

Scientific Knowledge and the Federal Courts 143 (1997) (quoting

Petr Skrabanek & James McCormick, Follies and Fallacies in Medicine

(1990)). Dr. Aprill conducted his tests in 1995; Messrs. Chaseling

and McDonald were summoned to Texas in 1996. It appears that the

vibration theory was developed to support Dr. Aprill’s analysis of

the MRIs. “This is fallacious because it confuses pre- and posttest probabilities.” Id. (quoting Skrabanek & McCormick, supra).

-64-

predicate to the plaintiffs’ recovery.22 Without a tie to the

particular injuries experienced by the plaintiffs, the opinions of

Dr. Bunch and Dr. Samaratunga shift on their foundations. In

essence, these two witnesses confirmed that the Euclid short-nose

coal hauler vibrates, that vibrations can cause back injury, and

that the plaintiffs who operated the short-nose coal hauler have

indeed suffered back injury. They relied on Dr. Aprill’s analysis

to connect their knowledge about the machine and theories about

whole body vibration to the plaintiffs’ flesh and blood. Their

testimony does not repair the fatal flaw in Dr. Aprill’s testimony.

The liability experts’ opinions that the Euclid short-nose

hauler may subject its operators to injury due to prolonged

exposure to harmful vibrations suffer from the same variety of

logical flaw -- they are not linked to the specific injury claimed

by the plaintiffs. Messrs. Chaseling and McDonald started with

their measurements of the vibrations produced by the short-nose

coal hauler. They then compared these findings to recommendations
-65-

by the ISO concerning what amount of vibration may be acceptable.

Having determined that the short-nose coal hauler’s level of

vibration is unacceptable according to ISO standards, these experts

then reasonably opined that exposure to too much vibration can be

harmful. All of this information is pertinent to the plaintiffs’

claims, but none of it provides the answer to the ultimate

question. None of it links the particularized information about

the vibrations experienced by the plaintiffs in this case to the

types of injuries experienced by the plaintiffs in this case. None

of it eliminates other possible sources of vibration as the cause

of the plaintiffs’ injuries. Their testimony therefore does not

permit the inference that the specific injuries claimed by the

plaintiffs were caused by the Euclid short-nose coal hauler.

Simply put, nothing in the evidence presented by Dr. Aprill or

any of the plaintiffs’ other experts suggests the required but-for

link between the short-nose hauler’s vibrations and the incidence

of endplate infractions in the plaintiffs’ backs. Explained yet

another way, even if Dr. Aprill’s study demonstrates that the

endplate infractions observed in the plaintiffs’ backs are more

likely than not attributable to some aspect of their occupation

(which, as a matter of logic, is all that his studies could

possibly demonstrate), the study does not link the Euclid shortnose hauler to the increased incidence of endplate infractions.

The study does not distinguish the effects of the Euclid short-nose
23 This is a fair characterization of the testimony given by Dr.

Samaratunga, who essentially provided an “expert” summarization of

previously admitted expert testimony, apparently for the purpose of

bridging the gaps and creating an illusion of logical cohesion.

24 The panel majority is absolutely correct in its statement of

law that if an “act actively aids in producing an injury, it need

not be the sole cause, but it might be a concurring cause, and such

-66-

coal hauler from the effects of any other kind of equipment

operated by the plaintiffs. Moreover, a mere “blend” of expert

opinions depicting a blurry relation resembling a causative link

between Euclid’s product and the plaintiffs’ injuries is

insufficient to support the verdict.23 “Proof of causation cannot

turn upon speculation or conjecture.” Leitch v. Hornsby, 935

S.W.2d 114, 119 (Tex. 1996) (internal quotation marks omitted).

The plaintiffs showed that they and their coworkers operated

the Euclid short-nose coal hauler. The plaintiffs demonstrated

that the Euclid short-nose coal haulers vibrate, and that may be a

bad thing. Finally, the plaintiffs explained that, in the opinion

of Dr. Aprill, they and their coworkers have endplate infractions

which appear in their spines in a unique fashion. But the

plaintiffs did not establish the crucial logical link -- that it

was the act of operating the short-nose coal haulers that caused

their endplate infractions. That logical lapse should be fatal to

their case. Because the plaintiffs have not presented evidence

that establishes that operating Euclid short-nose coal haulers was

a cause in fact of the plaintiffs’ endplate infractions, Euclid

should have been granted JMOL.24
as might reasonably be contemplated as contributing to the result.”

Majority Op. at Part IV(c) (citing McClure v. Allied Stores, Inc.,

608 S.W.2d 901, 904 (Tex. 1980)). The fact that there may be

multiple causes in fact for any given injury does not, however,

eradicate the requirement of proving but-for causation in this

case.

-67-

IV.

Euclid unsuccessfully sought to suppress the testimony of the

plaintiffs’ expert witnesses by challenging their qualifications to

present expert opinion. Euclid now challenges on appeal the

admission of plaintiffs’ experts’ testimony. This Court reviews

for abuse of discretion. See General Elec. v. Joiner, 118 S. Ct.

512, 517 (1997); Moore v. Ashland Chem. Inc., 151 F.3d 269, 274

(5th Cir. 1998) (en banc).

The Federal Rules of Evidence provide:

Rule 702. Testimony by Experts

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.

The Supreme Court’s decision in Daubert guides the application of

Rule 702. As our Court recently summarized:

[W]hen expert testimony is offered, the trial judge

must perform a screening function to ensure that

the expert’s opinion is reliable and relevant to

the facts at issue in the case. See Daubert, 509

U.S. at 589, 113 S. Ct. at 2794-95. Daubert went

on to make “general observations” intended to guide

a district court’s evaluation of scientific

evidence. The nonexclusive list includes “whether
-68-

[a theory or technique] can be (and has been)

tested,” whether it “has been subjected to peer

review and publication,” the “known or potential

rate of error,” and the “existence and maintenance

of standards controlling the technique’s

operation,” as well as “general acceptance.” 509

U.S. at 593-594, 113 S. Ct. at 2796-97.

Watkins v. Telsmith, Inc., 121 F.3d 984, 988-89 (5th Cir. 1997). 

A.

The plaintiffs’ experts’ opinions that the Euclid short-nose

coal hauler caused the plaintiffs’ back injuries were inadmissible

primarily because the substance of those opinions was not relevant

as a matter of law. Rule 702 permits expert opinion testimony only

in circumstances in which the opinion “will assist the trier of

fact to understand the evidence or to determine a fact in issue.”

For all of the reasons stated in Part III of this dissent, which

explained that the evidence was not sufficient to prove causation,

the evidence was furthermore inadmissible under Rule 702 for the

same reason. Because the substance of the expert opinion testimony

did not tend to prove causation, it was inadmissible as a matter of

law because it could not assist the jury. As the Supreme Court

explained:

Faced with a proffer of expert scientific

testimony, then, the trial judge must determine at

the outset . . . whether the expert is proposing to

testify to (1) scientific knowledge that (2) will

assist the trier of fact to understand or determine

a fact in issue. This entails a preliminary

assessment of whether the reasoning or methodology

underlying the testimony is scientifically valid
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and of whether that reasoning or methodology

properly can be applied to the facts in issue.

Daubert, 509 U.S. at 592-93, 113 S. Ct. at 2796 (footnotes omitted,

emphasis supplied); see also Daubert v. Merrell Dow Pharms., Inc.,

43 F.3d 1311, 1321 n.17, 1320-22 (9th Cir. 1995) (“Federal judges

must therefore exclude proffered scientific evidence under Rules

702 and 403 unless they are convinced that it speaks clearly and

directly to an issue in dispute in the case, and that it will not

mislead the jury.”); Kenneth R. Foster & Peter W. Huber, Judging

Science: Scientific Knowledge and the Federal Courts 34-36 (1997);

cf. Brock v. Merrell Dow Pharms., Inc., 874 F.2d 307, 311-15 (5th

Cir. 1989).

Without belaboring the point, it should be sufficient to note

the well-established requirement, grounded in Rule 702, that there

be a “fit” between the opinions offered by an expert and some

material issue in the case. If, as in this case, an expert’s

opinion is based on reasoning which as a matter of law is

insufficient to support the expert’s conclusion, that opinion

should not be admitted into evidence because, as a matter of law,

it cannot be helpful to the trier of fact and is therefore

inadmissible.

B.

The plaintiffs’ causation experts’ testimony that the Euclid

short-nose coal hauler caused the plaintiffs’ back injuries was
25 These supplemental factors were derived from United States v.

Downing, 753 F.2d 1224 (3d Cir. 1985), a pre-Daubert decision.

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also inadmissible because it was not scientifically reliable. In

deciding Euclid’s Daubert challenge, the district court

acknowledged the factors provided by the Supreme Court, and then

went on to list factors which it found compelling in this case: the

witnesses’ credentials; “a body of literature dealing with

repetitive trauma back injuries"; the fact that the theories could

be tested; and the fact that the “theories are derived from

methodology which relates to other accepted methodologies.”25 These

factors do not adequately ensure the reliability of the experts’

opinions.

Though the Supreme Court expressly noted that Daubert’s list

of factors is nonexclusive, it is certainly significant that the

testimony of Dr. Aprill is plainly inadmissible under those

original Daubert standards. The district court found that Dr.

Aprill’s hypothesis could be tested, but none of the other indicia

of reliability are present. The theory has not, in fact, been

tested. It has not been subjected to peer review or publication.

No known or potential rate of error has been provided. There are

no standards controlling the technique’s operation. There is no

suggestion that Dr. Aprill’s method is generally accepted.

There is a good reason why almost none of the original Daubert

criteria are satisfied by Dr. Aprill’s methodology. It is that
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there is an entire field of study devoted to the task which he

attempted. “Epidemiology is the field of public health that

studies the incidence, distribution, and etiology of disease in

human populations and applies the findings to alleviate health

problems.” Linda A. Bailey et al., Reference Guide on

Epidemiology, in Reference Manual on Scientific Evidence 123, 125

(Federal Judicial Center 1994) (emphasis in original). Dr. Aprill

did not use epidemiological methodology to come to his conclusions;

he generated a study for the purposes of this litigation and

offered an opinion about what it shows. This is precisely the sort

of ad hoc method of creating testimony that Rule 702 and Daubert

exclude.

The factors relied upon by the district court essentially

lower the Daubert bar. The court cited the witnesses’ credentials,

but plainly credentials are not enough. The court cited the

presence of “a body of literature” dealing with the type of

injuries claimed by the plaintiffs, but that factor completely

swallows Daubert’s inquiry into peer review and publication. As

Euclid points out, by that reasoning expert testimony about space

alien abductions would also be admissible. Likewise, the district

court’s reference to the fact that the plaintiffs’ experts’

“theories are derived from methodology which relates to other

accepted methodologies” simply lowers the standard set by Daubert’s

reliance upon “general acceptance.”
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In sum, the factors cited by the district court in support of

admitting the testimony of the plaintiffs’ experts seriously weaken

the standards of Rule 702 and Daubert. It was, therefore, an abuse

of discretion to consider these factors and admit the testimony.

V.

With respect to all of the original plaintiffs except Mr.

Johnny Bartley (who has since settled his claims against Euclid),

the claims are barred by limitations unless the discovery rule

applies. The jury found that the plaintiffs’ injuries were

inherently undiscoverable and objectively verifiable. These are

the two prerequisites to applying the discovery rule under Texas

law. See, e.g., Childs v. Haussecker, 974 S.W.2d 31, 36 (Tex.

1998); Computer Assocs. Int’l, Inc. v. Altai, Inc., 918 S.W.2d 453,

456 (Tex. 1994).

In this case, it is very plain that the plaintiffs’ injuries

are not what the Supreme Court of Texas considers to be

“objectively verifiable.” “Expert testimony . . . d[oes] not

supply the objective verification of wrong and injury necessary for

application of the discovery rule.” S.V. v. R.V., 933 S.W.2d 1, 7

(Tex. 1996). Objective verification is a “higher level of

certainty” than the mere preponderance of evidence required to find

liability. Cf. id. at 19. For example, a sponge left inside a

person by a surgeon is objectively verifiable. See Gaddis v.
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Smith, 417 S.W.2d 577 (Tex. 1967). In the context of a charge of

sexual abuse that was “discovered” after the alleged victim

recovered repressed childhood memories, the Supreme Court listed

the kinds of evidence that would qualify as objectively verifiable:

The kinds of evidence that would suffice would be a

confession by the abuser, e.g. Meiers-Post v.

Schafer, 170 Mich. App. 174, 427 N.W.2d 606, 610

(1988); a criminal conviction, e.g. Petersen v.

Bruen, 106 Nev. 271, 792 P.2d 18, 24-25 (1990);

contemporaneous records or written statements of

the abuser such as diaries or letters; medical

records of the person abused showing

contemporaneous physical injury resulting from the

abuse; photographs or recordings of the abuse; an

objective eyewitness’s account; and the like. Such

evidence would provide sufficient objective

verification of abuse, even if it occurred years

before suit was brought, to warrant application of

the discovery rule.

S.V., 933 S.W.2d at 15. 

Here, as in Robinson v. Weaver, 550 S.W.2d 18 (Tex. 1977),

“[e]ven the fact of injury is a matter of expert testimony.”

Robinson, 550 S.W.2d at 21 (quoted with approval in S.V., 933

S.W.2d at 7). There was dispute among the experts at trial as to

whether there is even such a thing as an “endplate infraction.”

The following dialogue occurred when Euclid cross-examined Dr.

Aprill at trial about his interpretations of the plaintiffs’ MRI

scans:

Q Now, sir, isn’t it true that the vast majority

of the articles that either you’ve written alone or

with other people, that the vast majority of these

articles have two radiologists, or at least two

radiologists, to look over the same scans that are
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the subject of those articles in order to see if

the radiologists agree with the interpretations?

A No, that is not true.

Q Well, sir, do you think that there’s a problem

or that there’s something wrong about having work

checked over to see if your interpretation of an

MRI is the same as somebody else’s?

A No, I don’t.

Q Have you had a radiologist, other than

yourself, look over your interpretations of these

MRIs in order to see if they agree with what you

said?

A No, I have not.

Q But radiologists other than you have reviewed

these MRIs, have they not, sir?

A I don’t know.

Q Have you not seen the reports done by Dr.

Gallman, the chief of radiology at Schumpert

Hospital, concerning your interpretation of these

MRIs?

A I saw his review of the interpretation of five

of the MRIs. There are 165 scans done, and I think

he commented on five.

Q We are talking about the five Plaintiffs in

this case, he commented upon those, did he not?

A Yes. Yes, he did.

Q And he disagreed with many of the things you

said, did he not sir?

A Yes, he did.

Q And he disagreed with the importance that you

placed on some of the things that you found, did he

not, sir?

A Yes, he did.
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Q And he disagreed with your opinions in this

case, did he not?

A Yes, he did.

Q Would you agree with me, sir, that different

radiologists have different styles interpreting

MRIs?

A Yes, they do.

Q I want to show you a statement out of the “New

England Journal of Medicine” . . . and ask if you

agree with this. . . . “This new study is also a

reminder that the interpretation of MRI findings

can vary substantially so that the results may be

equivocal despite the techniques or of

infallibility. Thus, for example, Jensen, et al

found that one expert neuroradiologist was 30

percent more likely to interpret a study as showing

a disc protrusion than a second expert

neuroradiologist reading the same films. This

variation, although no worse than that for many

other complex, clinical tests requiring expert

interpretation, creates further opportunities for

erroneous clinical decisions.” Would you agree

with that?

A Yes.

Q Some radiologists think certain things are

abnormal and some don’t, is that fair to say?

A Yes. Yes.

Q And there are a number of things that you

claim are abnormal on the MRIs of these Plaintiffs

here which other doctors do not think are abnormal;

isn’t that right, sir?

A I don’t know that for a fact. The only person

that I know that has commented on them is the

doctor that you mentioned.

The point was illuminated when Euclid presented its case. A

hospital’s chief radiologist presented as an expert witness, Dr.

William H. Gallman, III, had reviewed the plaintiffs’ MRIs. He
g:\opin\97-40365.dis -76-

testified that there was absolutely nothing unique or abnormal

about them. He further commented that although his practice

involved daily reviews and interpretations of MRIs, he had never

seen or heard the term “endplate infraction,” none of his

colleagues had seen or heard it, and he believed that Dr. Aprill

had fabricated the concept for the purpose of this litigation. The

phenomenon referred to by Dr. Aprill as an endplate infraction is,

in the opinion of Dr. Gallman, “extremely common,” having “no

significance” and seen “every day on multiple studies of different

patients of all walks of life.” Another of Euclid’s experts, Dr.

Malcolm Pope, distinguished professor in the Departments of

Biomedical Engineering, Orthopedic Surgery, Preventative Medicine,

and Mechanical Engineering at the University of Iowa, testified

that endplate infractions are “not a widely accepted abnormality”

and that “[s]ome radiologists would not even report it.”

Where even the fact of injury is disputed, and contested

expert testimony provides the only explanation for the cause of

that injury, it is impossible to conclude that the injury is

“objectively verifiable.” The discovery rule is an exception to

Texas statutes which otherwise limit the period of time in which

plaintiffs may seek redress for injuries. The Supreme Court of

Texas has made it clear that the discovery rule is not justified in

cases where the injury cannot be demonstrated by clear physical

evidence. The plaintiffs’ claims in this case are time-barred
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because they do not meet that high prerequisite to the application

of the discovery rule.

VI.

For the foregoing reasons, the judgment of the district court

should be reversed and judgment should be rendered in favor of

Euclid. Accordingly, I dissent from the panel majority’s contrary

conclusion.