Subject: IN THE SUPREME COURT OF TEXAS
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Date: Mon, 12 Mar 2007 19:43:24 -0500

IN THE SUPREME COURT OF TEXAS

════════════

No. 03-0526

════════════

Mack Trucks, Inc.,
Petitioner,

v.

Elizabeth Tamez et al.,
Respondents

════════════════════════════════════════════════════

On Petition for Review from the

Court of Appeals for the Thirteenth District
of Texas

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Argued October 20,
2004

Justice Johnson delivered the opinion
of the Court.

In this truck
accident case the trial court excluded expert testimony as to what caused a
post-accident fire that burned the truck and the driver. After excluding the
expert testimony because it was not reliable, the trial court granted summary
judgment. The court of appeals reversed. We hold that the trial court did not
err, reverse the court of appeals’ judgment, and render judgment that the
plaintiffs take nothing.

I. Background

On October
19, 1996, Abram Tamez was operating a Mack Truck tractor hauling a trailer of
crude oil. Tamez was rounding a curve in the road when the tractor and trailer
overturned. A fire erupted and burned the trailer, its cargo, and the tractor.
Tamez was able to climb out of the tractor, but he was badly burned and died as
a result of his injuries.

As a result
of Tamez’s death, suit was filed[1] against the tractor’s manufacturer,
Mack Trucks, Inc., and others.[2] The Tamezes alleged that Mack
defectively designed, manufactured and marketed the tractor. They claimed that
Mack was liable for negligence, gross negligence, strict products liability,
breach of warranty, and misrepresentation. All five theories were based on the
same complaint: diesel fuel from the truck’s fuel system originated the fire
that burned Abram Tamez. Specifically, the Tamezes alleged that the tractor had
design and manufacturing defects because (1) the fuel system was
unreasonably prone to fail and release diesel fuel in an environment conducive
to ignition and fire; and (2) the tractor had ignition sources such as hot
manifolds and electric batteries in areas likely to contain released flammable
fluids. The Tamezes also alleged that Mack failed to provide warnings about the
defects.

In connection
with its claims against Mack, the Tamezes identified Ronald Elwell as an expert
on post-collision, fuel-fed fires. Mack moved to exclude his testimony as
unreliable and moved for summary judgment. Mack asserted multiple grounds for
seeking summary judgment. Some grounds for its motion were directed at
particular plaintiffs, while some grounds were directed at all the Tamezes. One
part of Mack’s motion directed at all the Tamezes was a Rule 166a(i) motion
urging that the Tamezes could present no evidence that any alleged defects
caused the fire. The Tamezes responded to the no-evidence part of Mack’s motion,
in part, by filing Elwell’s deposition and his expert report. They also later
submitted Elwell’s testimony from a bill of exceptions.

Pretrial
matters, including a Robinson[3] hearing pursuant to Mack’s motion to
exclude Elwell’s testimony, were scheduled and heard. During the Robinson
hearing Elwell testified. He expressed the opinion that the fire was started by
the tractor’s battery, which was located too near the fuel tanks, igniting the
tractor’s diesel fuel, which in turn ignited the trailer’s cargo of crude oil.
The trial court granted Mack’s motion to exclude Elwell’s testimony as to
causation. The Tamezes later moved the trial court to reconsider its decision.
The court denied the motion but allowed the Tamezes to have Elwell testify again
to create a bill of exceptions.[4] The court signed an order excluding
the causation portion of Elwell’s testimony from being considered as evidence at
any trial or hearing because it was not sufficiently reliable. Mack’s motion for
summary judgment was granted.

The court of
appeals reversed the summary judgment, concluding that the trial court abused
its discretion in excluding Elwell’s causation testimony,[5] and also concluding that Elwell’s
testimony provided some evidence of causation. The court of appeals’ opinion
indicates that in reaching its decision it considered Elwell’s testimony from
both the Robinson hearing and the bill of exceptions. See 100
S.W.3d 549, 556, 559, 561.

Mack urges
that the trial court correctly excluded Elwell’s testimony on causation, did not
abuse its discretion in refusing to reconsider that ruling, and properly granted
summary judgment because the Tamezes presented no evidence of causation. Mack
asserts, among other matters, that the court of appeals erred by (1) considering
Elwell’s causation testimony from both the Robinson hearing and the bill
of exceptions; (2) reversing the trial court’s ruling as to admissibility of
Elwell’s causation testimony; and (3) reversing the summary judgment.

We conclude
that the trial court did not abuse its discretion in excluding Elwell’s
testimony on causation and that the court of appeals erred in considering
testimony from the bill of exceptions in evaluating the trial court’s exclusion
of Elwell’s causation testimony. We further conclude that the Tamezes presented
no summary judgment evidence of causation and summary judgment was properly
granted.

II. Elwell’s Bill of Exceptions Testimony

Mack argues
that the court of appeals erred by considering testimony admitted only for the
bill when it reviewed the trial court’s exclusion of Elwell’s causation
testimony. The Tamezes claim that whether Elwell’s bill of exceptions testimony
is considered is not relevant because his bill testimony added nothing to his
Robinson hearing testimony. Further, in their brief and at oral argument
the Tamezes disclaim having urged in the court of appeals that the trial court
erred in (1) holding a Robinson hearing, (2) the manner in which the
hearing was conducted, (3) the timing of the hearing, or (4) denying their
motion for reconsideration. Our review of their briefs in the court of appeals
confirms the Tamezes’ position. They do not contend here either that the bill of
exceptions testimony was improperly excluded or that the trial court erred in
denying their motion to reconsider.

The purpose
of a bill of exceptions is to allow a party to make a record for appellate
review of matters that do not otherwise appear in the record, such as evidence
that was excluded. Tex. R. App.
P. 33.2; Tex. R. Evid.
103(a)(2); see also In re Ford Motor Co., 988 S.W.2d 714, 721 (Tex.
1998). The court of appeals’ opinion indicates that it considered Elwell’s bill
of exceptions testimony in evaluating the admissibility of his opinions even
though the trial court did not. See 100 S.W.3d at 556, 559. As one
example, the court of appeals referenced Elwell’s opinion that at least one of
the tractor’s side fuel tanks became displaced during the rollover and separated
the balance line connecting the two fuel tanks. Id. at 557. The court
pointed to Elwell’s testimony interpreting photographic evidence of steel straps
which held the tanks as support for his opinion. Id. The referenced
testimony as to Elwell’s opinion and interpretation of photographic evidence was
given as part of his bill of exceptions testimony, but he did not give similar
testimony during the Robinson hearing.

Except for
fundamental error, appellate courts are not authorized to consider issues not
properly raised by the parties. See In the Interest of B.L.D., 113 S.W.3d
340, 350-52 (Tex. 2003). We have described fundamental error as those instances
in which error directly and adversely affects the interest of the public
generally, as that interest is declared by the statutes or Constitution of our
State, or instances in which the record affirmatively and conclusively shows
that the court rendering the judgment was without jurisdiction of the subject
matter. See McCauley v. Consol. Underwriters, 304 S.W.2d 265, 266 (Tex.
1957). The court of appeals did not classify the trial court’s refusal to allow
the Tamezes to present further evidence and to then reconsider its ruling to
exclude Elwell’s causation testimony as fundamental error, and neither do we.
The court of appeals erred in considering Elwell’s causation testimony from the
bill of exceptions without having first determined, pursuant to properly
assigned error, that the trial court erred in refusing to admit the testimony
and reconsider its decision to exclude Elwell’s causation opinions. Under the
record and issues presented to us, we may not consider Elwell’s testimony from
the bill of exceptions in determining whether the trial court erred in excluding
Elwell’s causation testimony. See Exito Elecs. Co. v. Trejo, 142 S.W.3d
302, 304 n.1 (Tex. 2004).

III. Reliability of Elwell’s Testimony

A. Standard of Review

An expert
witness may testify regarding “scientific, technical, or other specialized”
matters if the expert is qualified and if the expert’s opinion is relevant and
based on a reliable foundation. Tex. R.
Evid. 702; Helena Chem. Co. v. Wilkins, 47 S.W.3d 486, 499 (Tex.
2001); Robinson, 923 S.W.2d at 556. In determining whether expert
testimony is reliable, a court should examine “the principles, research, and
methodology underlying an expert’s conclusions.” Exxon Pipeline Co. v.
Zwahr, 88 S.W.3d 623, 629 (Tex. 2002). When the testimony involves
scientific knowledge, the expert’s conclusions must be “grounded ‘in the methods
and procedures of science.’” Robinson, 923 S.W.2d at 557 (quoting
Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 590 (1993)).
Otherwise, the testimony is “no more than ‘subjective belief or unsupported
speculation.’” Id. (quoting Daubert, 509 U.S. at 590). We have
identified several non-exclusive factors that trial courts should consider when
determining the reliability of expert testimony involving scientific
knowledge.[6] We recognize that these factors may
not apply when testimony is not scientific, but, rather, involves technical or
other specialized knowledge. Gammill v. Jack Williams Chevrolet, 972
S.W.2d 713, 726 (Tex. 1998). Even then, however, there must be some basis for
the opinion to show its reliability. Id. An expert’s bare opinion will
not suffice. Merrell Dow Pharms., Inc. v. Havner, 953 S.W.2d 706, 711
(Tex. 1997). And, there cannot be “‘too great an analytical gap between the data
and the opinion proffered.’” Gammill, 972 S.W.2d at 726 (quoting Gen.
Elec. Co. v. Joiner, 522 U.S. 136, 146 (1997)).

A trial court
has broad discretion in determining whether expert testimony is admissible.
Zwahr, 88 S.W.3d at 629. Its ruling will be reversed only if that
discretion is abused. K-Mart Corp. v. Honeycutt, 24 S.W.3d 357, 360 (Tex.
2000). Because the party sponsoring the expert bears the burden of showing that
the expert’s testimony is admissible, the burden of presenting understandable
evidence that will persuade the trial court is on the presenting party. See
Robinson, 923 S.W.2d at 557. When an expert’s “processes” or “methodologies”
are obscured or concealed by testimony that is excessively internally
contradictory, non-responsive or evasive, a trial court will not have abused its
discretion in determining that the expert’s testimony is not admissible. See
GMC v. Iracheta, 161 S.W.3d 462, 470-72 (Tex. 2005).

B. Reliability Factors

The court of
appeals noted that Elwell’s testimony largely applied his knowledge, training,
and experience to the underlying data and that his methodology was not easily
tested by objective criteria such as identifiable scientific formulas. The court
of appeals concluded that under such circumstances the reliability of Elwell’s
opinion is not properly measured by a Robinson–factor analysis, but that
the “analytical gap” test should be applied. 100 S.W.3d at 555-56.

Mack argues
that the court of appeals’ analysis is flawed. Mack urges that Elwell’s
inability to demonstrate at least one of the Robinson factors, coupled
with his inability to eliminate the crude oil tanker as the source of the fire,
rendered Elwell’s testimony unreliable. The Tamezes, on the other hand, argue
that because Elwell’s testimony was based on his training and experience, and
not science, application of the analytical gap test, as opposed to use of
Robinson factors, was appropriate. They contend that Elwell’s opinion was
reliable because there were no analytical gaps in his testimony. See
Gammill, 972 S.W.2d at 726.

In
Gammill we clarified that the list of non-exclusive factors listed in
Robinson may not be applicable when assessing certain kinds of expert
testimony. 972 S.W.2d at 720. We held that Robinson factors did not apply
to the mechanical engineer expert under consideration in Gammill, even
though his claimed expertise was scientific in nature. Id. at 727. In so
holding, however, we did not mean to imply that a trial court should never
consider the Robinson factors when evaluating the reliability of expert
testimony that is based on knowledge, training or experience, or that the
factors can only be applied when evaluating scientific expert testimony. We
recognized that the criteria for assessing reliability must vary depending on
the nature of the evidence. Id. at 726.

The United
States Supreme Court has noted that it is not possible to “rule out, nor rule
in, for all cases and for all time the applicability of the factors mentioned in
Daubert.” Kumho Tire v. Carmichael, 526 U.S. 137, 150 (1999). Nor
can the Court “now do so for subsets of cases categorized by category of expert
or by kind of evidence,” as “[t]oo much depends upon the particular
circumstances of the particular case at issue.” Id. In Robinson we
likewise explained that the factors mentioned do not constitute an exclusive
list and that the trial court’s gatekeeping inquiry will differ with each
particular case depending on the “[t]he factors a trial court will find helpful
in determining whether the underlying theories and techniques . . . are
scientifically reliable.” Robinson, 923 S.W.2d at 557. Thus, a trial
court should consider the factors mentioned in Robinson when doing so
will be helpful in determining reliability of an expert’s testimony, regardless
of whether the testimony is scientific in nature or experience-based. See
Kumho Tire, 526 U.S. at 139; Gammill, 972 S.W.2d at 726.

In
determining reliability, the trial court “should undertake a rigorous
examination of the facts on which the expert relies, the method by which the
expert draws an opinion from those facts, and how the expert applies the facts
and methods to the case at hand.” See Amorgianos v. Amtrak, 303 F.3d 256,
267 (2d Cir. 2002). A significant part of the trial court’s gatekeeper function
is to evaluate the expert’s qualifications, listen to the testimony, view the
evidence, and determine which factors and evaluation methodology are most
appropriate to apply. For example, in the present case the trial court would
have been within its discretion to measure the reliability of Elwell’s
testimony, at least in part, by considering (1) the extent to which Elwell’s
theory had been or could be tested; (2) the extent to which his methodology
relied upon his subjective interpretation; (3) the methodology’s potential rate
of error; (4) whether the underlying theory or methodology has been generally
accepted as valid by the accident reconstruction and post-collision fire
investigation community; and (5) the non‑judicial uses that have been made of
his methodology. These are similar to factors 1, 2, 4, 5 and 6 of those
enumerated in Robinson. But, as we have said above, that is not to imply
that the trial court was precluded from measuring Elwell’s methodology by
Gammill’s analytical gap analysis.

C. Elwell’s Causation Testimony

At the
Robinson hearing, Elwell testified that the fuel and battery system on
the tractor were designed improperly, and suggested safer designs. He criticized
the placement of the fuel tanks and also of the batteries’[7] proximity to the fuel tanks. He
criticized certain parts of the fuel system such as the crossover or “balance
line” hose between the two fuel tanks and the spigots by which the hose was
attached to each of the tanks. He referenced a particular report, which was not
introduced, which he asserted supported his design critiques and his suggested
safer designs.

Elwell’s
analysis and conclusion that the fire began with the fuel system and the battery
system were based on the “fire triangle” theory. He explained that under the
fire triangle theory, a post-collision fuel-fed fire such as the one under
consideration must be analyzed with an eye toward the ignition, fuel, and oxygen
sources that were available. Because the air provided oxygen, his analysis
centered on the other parts required to complete the triangle, “the source of
fluids that could be ignited and what would it take to ignite those fluids and
fuel, of course, is the primary suspect, either fuel or crude oil in this
particular case.”

He did not
testify that he inspected the remnants of the burned tractor and trailer or that
he performed or reviewed any accident reconstruction analysis as to how the
rollover occurred and how different parts of the vehicle would have been
affected or harmed thereby. His Robinson hearing testimony did not
identify a particular alleged defect of the tractor’s fuel system which he
concluded was the source of a diesel fuel leak that initiated the fire.

On
cross-examination he testified that he had read and relied on “over 5,000”
studies on the subject of the causes of post-collision fuel-fed fires. He did
not specify any studies that supported his conclusion as to the specifics
involved in the accident, and none were offered as evidence for the trial court
to consider in evaluating his testimony.

In coming to
his conclusion that the fire began with the fuel system and battery system of
the tractor, Elwell asserted that he relied on several specific factors and
facts. Each of the factors and facts he enumerated supported conclusions that
Tamez was burned by diesel and that the diesel ignited so quickly that Tamez
could not escape.

Even assuming
that what Elwell relied on and classified as “factors” and “facts” were true,
however, which Mack denies, the factors and facts are merely consistent with
diesel fuel having been released during the rollover and Tamez having been
burned by part of the fire fed by the tractor’s diesel fuel. They are not
probative evidence that diesel fuel was released because of one of the asserted
defects in the fuel system or that it was ignited by the battery system. He did
not testify to having analyzed, tested, or investigated the characteristics of
batteries like the battery in the wrecked tractor to support his opinion that
the battery system was involved in causing the fire. He failed to set out any
process by which he excluded other sources for ignition of the diesel fuel such
as mechanical sparks which could be generated when parts of a truck make contact
with the pavement, or ignition of the cargo fuel which in turn could have
ignited the diesel fuel. See Gammill, 972 S.W.2d at 728; see also
Robinson, 923 S.W.2d at 559 (noting that an expert who is trying to find a
cause of something should carefully consider alternative causes). For example,
when Elwell was asked during the Robinson hearing why he concluded that
the fire originated with the fuel and battery systems instead of with the crude
oil cargo, his response was that “if [crude oil] remains to be burned, that
after five or ten or fifteen minutes, then that’s not the fuel that started the
fire.” He did not explain any investigation or research that supported such a
conclusion. He did not elaborate on the amount of crude that was in the trailer
when the wreck occurred, calculate the amount of time it would take the cargo to
burn, or discuss or compare the relative ease of ignition or flash points of the
crude and diesel fuel. He did not address any analysis or process by which he
concluded that some part of a trailer of crude oil would continue to burn for
several minutes only if it was ignited by, rather than being the ignitor of,
diesel fuel from the tractor’s fuel system.

In sum,
Elwell did not testify at the Robinson hearing to a methodology by which
he reached his conclusion that the fire had been caused by defects in the
tractor’s fuel and battery systems. In order for Elwell’s testimony on causation
to be reliable, he was required to present some methodology that reliably
supported his opinions that the “fuel” and “ignition” parts of the fire triangle
were supplied, respectively, by the tractor’s alleged fuel system defects and
battery system. He did not do so. The mere fact that the fuel system had a
design that could cause the hoses to separate is not evidence that the hoses
separated in this case.

Elwell’s
testimony did no more than set out “factors” and “facts” which were consistent
with his opinions, then conclude that the fire began with diesel fuel from the
tractor. The reliability inquiry as to expert testimony does not ask whether the
expert’s conclusions appear to be correct; it asks whether the methodology and
analysis used to reach those conclusions is reliable. Kerr-McGee Corp. v.
Helton, 133 S.W.3d 245, 254 (Tex. 2004). The trial court was not required to
accept his opinions at face value just because Elwell was experienced in
examining post-collision fuel-fed fires. See Gammill, 972 S.W.2d at 726
(holding that a court should not admit opinion evidence which is connected to
existing data only by the ipse dixit of the expert).

We conclude
that the trial court did not abuse its discretion when it excluded Elwell’s
testimony on causation. The court of appeals erred when it determined
otherwise.

IV. The Summary Judgment

Mack moved
for summary judgment on multiple grounds, including the ground that there was no
evidence Mack’s fuel system design was a producing or proximate cause of Tamez’s
injuries. The Tamezes contend that even without Elwell’s testimony as to
causation, they presented sufficient evidence to survive summary judgment.

A. Standard of Review

A summary
judgment motion pursuant to Tex. R. Civ.
P. 166a(i) is essentially a motion for a pretrial directed verdict.
See Merrell Dow Pharms., Inc. v. Havner, 953 S.W.2d 706, 711 (Tex. 1997).
Once such a motion is filed, the burden shifts to the nonmoving party to present
evidence raising an issue of material fact as to the elements specified in the
motion. Id.; W. Invs., Inc. v. Urena, 162 S.W.3d 547, 550 (Tex.
2005). We review the evidence presented by the motion and response in the light
most favorable to the party against whom the summary judgment was rendered,
crediting evidence favorable to that party if reasonable jurors could, and
disregarding contrary evidence unless reasonable jurors could not. See
City of Keller v. Wilson, 168 S.W.3d 802, 827 (Tex. 2005); Johnson v.
Brewer & Pritchard, P.C., 73 S.W.3d 193, 208 (Tex. 2002).

B. Causation

Producing or
proximate cause is an element of all of the Tamezes’ claims, which included
negligence, misrepresentation, breach of warranty, and design, manufacturing,
and marketing defects. Causation-in-fact is common to both proximate and
producing cause, including the requirement that the defendant’s conduct or
product be a substantial factor in bringing about the injuries in question.
See Union Pump Co. v. Allbritton, 898 S.W.2d 773, 775 (Tex. 1995).

All the
Tamezes’ theories regarding the fire’s cause were based on allegations that the
tractor’s fuel system was defectively designed and manufactured so as to be
unreasonably prone to fail and release flammable fluids in an environment
conducive to ignition and fire; that such defects caused the release of diesel
fuel; and that a defectively designed and placed ignition source then caused
ignition of the released diesel.

To survive
summary judgment on their theory that a defect in the tractor’s fuel system was
the cause of the fire, the Tamezes were required to present more than evidence
of a fuel leak. See Ford Motor Co. v. Ridgway, 135 S.W.3d 598, 600-01
(Tex. 2004) (affirming summary judgment because the plaintiffs’ evidence
“establishe[d] only that a fire occurred, and [the plaintiffs’ expert] could say
no more than that he ‘suspects’ the electrical system caused the fire”). They
had to present evidence that (1) the diesel fuel leaked because of one or more
of the alleged defects, and (2) the leak caused by the defect was the ignition
point for the fire. See Iracheta, 161 S.W.3d at 470 (holding that the
possibility that the fire occurred in the manner the plaintiff suggested is not
enough to support the jury’s findings); Nissan Motor Co. v. Armstrong,
145 S.W.3d 131, 137 (Tex. 2004).

The Tamezes
point to several parts of their summary judgment evidence that they say are
sufficient, individually or collectively, to defeat summary judgment:
(1) an accident witness’s “personal assumption,” based on his averred
experience with and ability to recognize the smell of diesel fuel, that Tamez
was burned by diesel fuel because Tamez was coated with a shiny, oily substance
and did not smell like crude oil; (2) a notation by Mack’s accident
reconstruction expert noting a diesel fuel spill on the road; (3) a
statement by Elwell that the design of the system was such that if there was any
significant dislodgement of the fuel tanks, the fuel line would separate;[8] (4) a statement by Mack’s expert
witness that it was possible that a battery cable found in the tractor had arced
and ignited the fire, although the witness ultimately concluded that the
crude-oil cargo caused the fire; and (5) an eyewitness’s statement implying
that it took the fire a short period of time to reach Tamez, who exited and
crawled away from the tractor after the accident.

Proof other
than expert testimony will constitute some evidence of causation only when a
layperson’s general experience and common understanding would enable the
layperson to determine from the evidence, with reasonable probability, the
causal relationship between the event and the condition. Expert testimony is
required when an issue involves matters beyond jurors’ common understanding.
See Alexander v. Turtur & Assocs., 146 S.W.3d 113, 119-20 (Tex.
2004). Whether expert testimony is necessary to prove a matter or theory is a
question of law. See FFE Transp. Servs., Inc. v. Fulgham, 154 S.W.3d 84,
89 (Tex. 2004). In Fulgham we held that expert testimony was necessary to
establish the standard of care for connecting refrigerated trailers to tractors
and for the frequency and type of inspection and maintenance of such connectors,
because those matters were not within the general experience and common
understanding of laypersons. Id. at 91; see also Turbines, Inc. v.
Dardis, 1 S.W.3d 726, 738 (Tex. App.–Amarillo 1999, pet. denied) (holding
that performance of mechanical work on turbine aircraft engines is not within
the experience of a layperson).

A lay juror’s
general experience and common knowledge do not extend to whether design defects
such as those alleged in this case caused releases of diesel fuel during a
rollover accident. See Nissan Motor Co., 145 S.W.3d at 137 (stating that
we have consistently required competent expert testimony and objective proof
that a defect caused the condition complained of). Nor would a lay juror’s
general experience and common knowledge extend to determining which of the fire
triangle’s fuel sources, diesel from the tractor or crude from the tanker, would
have first ignited, or the source for the first ignition. That part of Elwell’s
testimony that was properly before the trial court and the testimony of other
experts as to the amount of time they spent in studying, investigating, and
working in the field of post-collision, fuel-fed fires demonstrated the
intricacies of such subject matter. Issues such as those regarding the fire’s
cause(s) present matters beyond the general understanding and common knowledge
of lay jurors. Proof of causation in this case also required expert
testimony.

The summary
judgment evidence presented by the Tamezes did not contain proof that any of the
possible sources of diesel fuel was more likely than any other, or more likely
than the crude oil cargo, to have been the source of liquids that first caught
fire. Accordingly, there is no evidence that the source was one of the alleged
fuel system defects. Kindred v. Con/Chem, Inc., 650 S.W.2d 61, 63 (Tex.
1983).

The Tamezes
also alleged that several ignition sources were located in areas likely to
contain diesel that would be released in a wreck. The Tamezes point to expert
testimony that an arced battery cable found in the tractor could possibly have
ignited the fire. But, testimony that the battery or its cable could possibly
have ignited the fire is not evidence that it probably did so. The expert who
provided this testimony could not determine whether the cable arced before the
fire was ignited or as it was being burned by an otherwise-ignited fire. As
proof of what caused the fire, such evidence is speculative and is insufficient
to prevent summary judgment. See Wal-Mart Stores, Inc. v. Gonzalez, 968
S.W.2d 934, 936 (Tex. 1998).

The
plaintiffs also rely on circumstantial evidence suggesting that the fire quickly
reached Tamez. That evidence is consistent with the Tamezes’ theory that the
fire originated with fuel from the tractor’s diesel fuel system. But, such
evidence does not make it more likely than not that the battery or some other
allegedly improperly located ignition source ignited diesel from the tractor, as
opposed to other possible sources of ignition such as the cargo of crude oil.
Accordingly, the circumstantial evidence is not sufficient to prevent summary
judgment. Id.

V. Conclusion

The
plaintiffs produced no evidence that the alleged defects of the Mack tractor
were a cause-in-fact of injuries to Abram Tamez. Because causation is a required
element of each of the Tamezes’ claims, the trial court properly granted summary
judgment. Accordingly, we reverse the court of appeals’ judgment and render
judgment that the plaintiffs take nothing.

________________________________________

Phil
Johnson

Justice

OPINION DELIVERED: October
27, 2006

[1] Elizabeth Tamez filed suit. Elsa Guerrero, Rosendo
Tamez, Sr., Dora Tamez, Rosa Elvia Gonzales, Donna Kim Cantu, and Terrie L. Zay
intervened. Rosa subsequently nonsuited. For ease of reference all the claimants
will be referred to collectively as “the Tamezes” or “the
plaintiffs.”

[2] Other defendants were Fruehauf Trailer Corporation,
Norco Crude Gathering, Inc., Glitsch Canada, Ltd., and Snyder Tank Corp. The
claims against those defendants were either nonsuited or settled and were
severed from the claims against Mack.

[3] E.I. du Pont de Nemours & Co. v. Robinson,
923 S.W.2d 549 (Tex. 1995).

[4] An offer of proof is sometimes referred to as a bill of
exceptions. See Tex. R. Evid.
103(a)(2); Tex. R.
App. P. 33 (comment to 1997 change). As the court of appeals and the
parties refer to the offer of proof in this case as a bill of exceptions, we
will, also.

[5] After Elwell’s expert testimony was excluded by the
trial court, the Tamezes obtained testimony from another expert witness, Douglas
Holmes. Mack moved to exclude Holmes’s testimony, and the trial court orally
granted the motion. The court of appeals upheld the exclusion of Holmes’s
testimony. 100 S.W.3d 549, 559. The Tamezes do not challenge the court of
appeals’ ruling as to Holmes.

[6] Id. (identifying the following considerations
regarding reliability of scientific testimony: (1) the extent to which the
theory has been or can be tested; (2) the extent to which the technique
relies upon the subjective interpretation of the expert; (3) whether the
theory has been subjected to peer review and/or publication; (4) the
technique’s potential rate of error; (5) whether the underlying theory or
technique has been generally accepted as valid by the relevant scientific
community; and (6) the non-judicial uses that have been made of the theory
or technique).

[7] The record is not clear whether the tractor had one
battery or two.

[8] Elwell’s testimony on design defect, as opposed to his
testimony on causation, was not
excluded.