FILED
United States Court of Appeals
Tenth Circuit

DEC 6 2004

PATRICK FISHER
Clerk
PUBLISH

UNITED STATES COURT OF APPEALS

TENTH CIRCUIT



FRED D. BITLER; PEGGY A. BITLER; No. 02-1527
COLORADO COMPENSATION INSURANCE
AUTHORITY, a political subdivision
of the State of Colorado,

Plaintiffs - Appellees,

v.

A.O. SMITH CORPORATION, a foreign
corporation; NATIONAL PROPANE
CORP., formerly known as All
Seasons Propane, a Colorado
corporation,

Defendants,

and

WHITE RODGERS, a subsidiary of
EMERSON ELECTRIC CORP., a foreign
corporation,

Defendant - Appellant.



Appeal from the United States District Court
for the District of Colorado
(D.C. Nos. 98-N-1897 and 98-BB-1897)




Daniel A. Nelson (Bruce A. Lampert, with him on the briefs), Schaden, Katzman,
Lampert & McClune, Broomfield, Colorado, for Plaintiffs-Appellees Fred and
Peggy Bitler.

Andrew M. Low (Peter J. Krumholz, with him on the briefs), Davis, Graham &
Stubbs LLP, Denver, Colorado, for Defendant-Appellant.



Before LUCERO, McKAY, and HARTZ, Circuit Judges.



LUCERO, Circuit Judge.

Danger lurked in Fred and Peggy Bitler's basement, liability for which is
the occasion for the present appeal. Mr. Bitler was severely burned when a gas
explosion occurred in the basement of his home. On filing a products liability
suit against, inter alia, White-Rodgers as manufacturer of the gas control installed
in his basement water heater, a jury returned a verdict finding negligence and
product defect and awarded damages to the Bitlers. White-Rodgers' motions for
JNOV and a new trial having been denied by the district court, the present appeal
followed. In contesting the jury verdict imposing products liability on it for the
explosion, White-Rodgers assigns as principal error the district court's admission
of plaintiffs' expert testimony under Daubert principles. We exercise jurisdiction
under 28 U.S.C. _ 1291 and AFFIRM.

I


Fred and Peggy Bitler resided in a house provided for their use on the Oldland
Ranch outside of Meeker, Colorado where Fred Bitler was a ranch hand.
On the evening of the accident, July 25, 1996, Bitler discovered that there was no
hot water when he attempted to shower. Hot water was supplied to the Bitlers'
home by a liquid propane hot water heater located in the basement. Donning
sweat pants, he proceeded to the basement door, unlatched it, and walked
approximately two-third's of the way down the staircase when a large explosion
occurred, knocking him backwards. His wife, Peggy Bitler, was thrown off a sofa
and onto the floor, which was later determined to have been raised several inches
by the force of the explosion. Fred Bitler sustained severe burns, and after being
flown by helicopter to a hospital, underwent multiple skin graft surgeries over the
following weeks. It was established at trial that he has, in addition to general
disfigurement, continuing problems with regulation of his body temperature, use
of his hands, growth of hair follicles, and he will also need additional procedures
in the future to develop nail growth on his hands. As a result of the injuries he
sustained in this accident, he is no longer able to perform the duties appertaining
to his former occupation as a cowboy and ranch hand.
There were three gas propane appliances in the Bitlers' home Ä a cook
stove in the kitchen, a furnace in a bedroom, and a space heater in one of the
bedrooms. Gas was supplied to the water heater via unsupported, flexible copper
tubing that ran along the basement ceiling joints. A "T-fitting" was located above



the hot water heater which provided branches running to the hot water heater and
the space heater. Post-accident inspection revealed a minor leak at the inlet to the
bedroom heater, and a leak at the "T-connector."
White-Rodgers, a subdivision of Emerson Electric Co., manufactured the
water heater gas control used in the Bitlers' hot water heater. This gas control
regulates the flow of gas to the pilot and main burner of the water heater, and is
designed to fulfill a crucial safety role if the pilot light is extinguished. To avoid
a gas leak that could lead to an explosion or fire, the gas control is designed to
shut off all gas flow to the pilot when the pilot is extinguished. As is well
known, a lit pilot heats a thermocouple which in turn creates an electric current
energizing an electromagnet that holds the safety valve open against the force of a
spring. So long as the pilot is lit, the safety valve remains open. If the pilot goes
out, however, the thermocouple will no longer be heated and will no longer
produce a current to energize the electromagnet, allowing the spring to snap the
valve shut. The safety valve seat is made of rubber, and is designed to create a
seal against a circular metal surface when closed to prevent the flow of gas to the
pilot.
Copper sulfide is a frequent contaminate found in gas and propane lines. If
copper sulfide particles of sufficient size become lodged on a safety valve seat
when a pilot is extinguished, the particles may prevent the valve from sealing,



resulting in a gas leak. It was established that numerous accidents have occurred
in this manner, and that copper sulfide contamination was a significant source of
concern for White-Rodgers. As a consequence, White-Rodgers modified the
design of the safety valve in 1978 and began installing a wire mesh screen in the
gas inlet, upstream from the safety valve to prevent copper sulfide particles from
migrating onto the rubber valve seat. In further recognition of the safety hazard
caused by copper sulfide contamination, White-Rodgers recalled all gas controls
lacking the mesh screen in 1980. Thereafter, White-Rodgers also began adding
another safety feature to the mesh screen by installing a deflection "baffle" to aid
in preventing debris from reaching the valve and to hold the edges of the mesh
screen in place more effectively. The safety valve installed in the Bitler's water
heater was one of about 200,000 devices produced in the interim that contained
the mesh screen, but did not contain the baffle.
As a result of their investigations, plaintiffs' expert Elden Boh concluded
that the water heater was the source of the accident, and plaintiffs' expert Donald
Sommer concluded that the leak was caused by copper sulfide contamination on
the water heater's safety valve seat. Elden Boh is a fire investigator hired by the
Colorado Farm Bureau, and Donald Sommer is an engineer and accident
investigator retained by the Bitlers. Although White-Rodgers contests the
admissibility of these two experts on appeal, plaintiffs' expert W. Alan



Bullerdiek, a chemical engineer, also testified concerning the history of copper
sulfide-contamination-related accidents, and that the amount of contamination
found on the Bitlers' safety valve seat was at an unacceptable level.
During post-accident testing of the safety valve installed in the Bitlers'
water heater, the device was disassembled in the presence of representatives of
both White-Rodgers and the Bitlers. Copper sulfide particulate contamination
was discovered downstream of the mesh screen and found on the safety valve
seat. During the teardown, a test of the valve revealed that it snapped shut as
designed. Plaintiffs' expert, Donald Sommer, opined at trial that a mix of copper
sulfide particles and grease located on the safety valve seat caused the leak. Mr.
Sommer testified that the valve seat was altered after the accident when the
control was turned to the "off" position; furthermore, he testified that because
copper sulfide contamination leads to intermittent leaks, the teardown test could
not be determinative. Whether the particles found on the safety valve were large
enough or of sufficient quantity to have caused the gas leak in the present case is
hotly disputed.
Having marshaled their expert witnesses and having ruled out to their
satisfaction all other sources of the gas leak save for the gas control on the water
heater, the Bitlers filed suit in Colorado state court against White-Rodgers, as
well as A.O. Smith Corporation, which manufactured the water heater, and



National Propane Corporation, which installed and maintained the water heater
and propane piping in the house. After removing the case to federal district court,
defendants moved for summary judgment, contesting the admission of the
plaintiffs' expert testimony as insufficiently reliable and lacking a firm
foundation in science. In an order denying the motion, the trial judge found that
the Bitlers' proposed expert testimony was relevant and reliable in accord with
the standard required by Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579
(1993). The matter proceeded to a two-week jury trial, at the close of which the
jury returned a verdict against White-Rodgers and National Propane, attributing
fifty percent of the fault to National Propane and forty percent to White-Rodgers,
and awarding $2,319,492.27 in damages to the Bitlers. As to White-Rodgers
specifically, the jury found both negligence and product defect. In its order of
October 30, 2002, the district court denied White-Rodgers' motions for judgment
as a matter of law and for a new trial. This appeal followed.
II
We review de novo whether the district court properly performed its role as
"gatekeeper" in admitting or excluding expert testimony. Dodge v. Cotter Corp.,
328 F.3d 1212, 1223 (10th Cir. 2003) ("Though the district court has discretion in
how it conducts the gatekeeper function, we have recognized that it has no
discretion to avoid performing the gatekeeper function."). We review for abuse



of discretion the manner in which the district court exercises its Daubert
"gatekeeping" role in making decisions whether to admit or exclude testimony.
General Elec. Co. v. Joiner, 522 U.S. 136, 139 (1997). We will not, however,
disturb a district court's ruling absent our conviction that it is arbitrary,
capricious, whimsical, manifestly unreasonable, or clearly erroneous. Goebel v.
Denver and Rio Grande W. R.R. Co., 346 F.3d 987, 990 (10th Cir. 2003). The
district court must, however, make specific factual findings on the record which
are sufficient for an appellate court to review the trial court's conclusion
concerning whether the testimony was scientifically reliable and factually
relevant. Dodge, 328 F.3d at 1223. Our standard of review of a trial court's
factual findings in pursuit of its gatekeeping role does not vary when examining
exclusion or admission of expert testimony. Our focus on review mirrors that of
the trial judge's assessment of the testimony itself: we are concerned with the
trial court's performance of its obligation under Rule 702 and Daubert, not upon
the exact conclusions reached to exclude or admit expert testimony. See Goebel,
346 F.3d at 1001 (holding that district court did not abuse its discretion in
admitting expert testimony); Mitchell v. Gencorp Inc, 165 F.3d 778, 784 (10th
Cir. 1999) (holding that the district court did not abuse its discretion in excluding
expert testimony). Thus, although the district court "must, on the record make
some kind of reliability determination," United States v. Velarde, 214 F.3d 1204,



1209 (10th Cir. 2000), we recognize the wide latitude a district court has in
exercising its discretion to admit or exclude expert testimony.
A
White-Rodgers assigns as a principal source of error the district court's
performance of its Daubert gatekeeping functions. We begin our inquiry into the
admissibility of the Bitlers' expert testimony with Fed. R. Evid. 702. In accord
with Rule 702, the Supreme Court has determined that the trier of fact "must
ensure that any and all scientific testimony or evidence is not only relevant, but
reliable." Daubert, 509 U.S. at 589. To fulfill its gatekeeping role, a district
court must therefore conduct a two-part inquiry.
First, a district court must determine if the expert's proffered testimony Ä
whether it concerns scientific, technical, or other special knowledge Ä has "a
reliable basis in the knowledge and experience of his [or her] discipline." Id. at
592; see also, Kuhmo Tire Co. v. Carmichael, 526 U.S. 137, 149 (1999) (holding
that Daubert's general principles apply to all expert matters under Rule 702). By
conducting a preliminary inquiry into the expert's qualifications and the
admissibility of proffered evidence, a district court fulfills its initial obligation
under Fed. R. Evid. 104(a) ("Preliminary questions concerning the qualification
of a person to be a witness . . . or the admissibility of evidence shall be
determined by the court"). To determine whether expert testimony is admissible



requires a trial court to examine "whether the reasoning or methodology
underlying the testimony is scientifically valid . . . ." Daubert, 509 U.S. at 592-
93. In order to establish an expert's testimony as reliable, we have held that:
The plaintiff need not prove that the expert is undisputably correct or that
the expert's theory is "generally accepted" in the scientific community.
Instead, the plaintiff must show that the method employed by the expert in
reaching the conclusion is scientifically sound and that the opinion is based
on facts which sufficiently satisfy Rule 702's reliability requirements.

Mitchell, 165 F.3d at 781 (citation omitted).
Providing guidance as to the kinds of factors that might bear on a judge's
gatekeeping determination, the Supreme Court has suggested that a court
consider: (1) whether a theory has been or can be tested or falsified, (2) whether
the theory or technique has been subject to peer review and publication, (3)
whether there are known or potential rates of error with regard to specific
techniques, and (4) whether the theory or approach has "general acceptance."
Daubert, 509 U.S. at 593-94. The Court has made clear, however, that this list is
neither definitive nor exhaustive and that a trial judge has wide discretion both in
deciding how to assess an expert's reliability and in making a determination of
that reliability. Kuhmo Tire Co., 526 U.S. at 150, 152-53; see also Velarde, 214
F.3d at 1208-09. While these factors are most relevant in the context of a new
and novel scientific theory Ä asking if it has been tested, subjected to peer review
and publication, etc. Ä they do provide examples of the general kinds of issues a



trial court need probe in light of its purpose of ensuring that an expert "employs
in the courtroom the same level of intellectual rigor that characterizes the practice
of an expert in the relevant field." Kumho Tire, 526 U.S. at 152. Failure to
consider one, or even any, of these factors, albeit suggestive, will not be
dispositive of a district court's failure to fulfill its gatekeeping role because that
role depends on the underlying factual circumstances of the particular case.
Accordingly, a trial court's focus generally should not be upon the precise
conclusions reached by the expert, but on the methodology employed in reaching
those conclusions. Daubert, 509 U.S. at 595. Although it is not always a
straightforward exercise to disaggregate method and conclusion, when the
conclusion simply does not follow from the data, a district court is free to
determine that an impermissible analytical gap exists between premises and
conclusion. See Joiner, 522 U.S. at 146; Dodge, 328 F.3d at 1222. When
examining an expert's method, however, the inquiry should not be aimed at "the
exhaustive search for cosmic understanding but for the particularized resolution
of legal disputes." Daubert, 509 U.S. at 597.(1) Thus it is the specific relation
between an expert's method, the proffered conclusions, and the particular factual
circumstances of the dispute, and not asymptotic perfection, that renders
testimony both reliable and relevant.
Second, in fulfilling its Daubert obligations a trial court must also conduct
a further inquiry into whether proposed testimony is sufficiently "relevant to the
task at hand." Daubert, 509 U.S. at 597. Relevant evidence "means evidence
having any tendency to make the existence of any fact that is of consequence to
the determination of the action more probable or less probable than it would be
without the evidence." Fed. R. Evid. 401. The Supreme Court has described the
consideration of relevant evidence as one of "fit." Daubert, 509 U.S. at 591. A
trial court must look at the logical relationship between the evidence proffered
and the material issue that evidence is supposed to support to determine if it
advances the purpose of aiding the trier of fact. Even if an expert's proffered
evidence is scientifically valid and follows appropriately reliable methodologies,
it might not have sufficient bearing on the issue at hand to warrant a
determination that it has relevant "fit." Id. Testimony concerning the laws of
(1) Determining whether proffered testimony is scientifically reliable can be
a considerable challenge for a trial judge. As Justice Breyer has noted, "this
requirement will sometimes ask judges to make subtle and sophisticated
determinations about scientific methodology and its relation to the conclusions an
expert witness seeks to offer - particularly when a case arises in an area where
the science itself is tentative or uncertain. . . ." Joiner, 522 U.S. at 147-48
(Breyer, J., concurring). To fulfill this task, however, as Judge Posner has
observed, "we do not have to become philosophers of science and set forth the
necessary and sufficient conditions of `real' science," or endeavor to discover
"the essence of `science,' if there is such an essence." Rosen v. Ciba-Geigy
Corp., 78 F.3d 316, 318 (7th Cir. 1996). We may leave the philosophy of science
to the philosophers.



quantum mechanics may be scientifically relevant, but may have no practical
relevance to testimony concerning the function and possible failure of a water
heater safety valve control. Evidence appropriate for one purpose, therefore, may
not be relevant for a different purpose, and it is the trial court's task to make this
fitness determination.
B
In fulfilling its Daubert gatekeeping function, the district court, in its order
denying summary judgment to the defendants, focused on two expert witnesses
proposed by the Bitlers: Elden Boh and Donald Sommer. On reviewing the
record, we note that the actual testimony offered at trial does not differ in
material respects from either Boh's or Sommer's depositions as analyzed by the
district court on motions for summary judgment. Nonetheless White-Rodgers
argues that the magistrate judge was required to perform a gatekeeping role by
entertaining anew, during pre-trial proceedings, defendant's objections to the
testimony of Sommer; the magistrate judge instead treated District Judge
Nottingham's order denying summary judgment as law of the case, and refused to
consider de novo the issue of whether to admit the Bitlers' expert testimony. It is
clear, however, that because White-Rodgers did not raise new issues concerning
the reliability of the Bitlers' expert witnesses, the district court did not fail to
perform its Daubert role merely by refusing to reconsider the question of



admissibility that had already been decided. Daubert does not require a district
court to linger at the "gate," as if caught in Zeno's paradox, unable to proceed to
the main trial without first conducting a series of mini-trials with regard to every
objection raised against a party's expert witnesses.
As to reliability regarding Boh's testimony, the district court specifically
found that Boh's methodology in reaching his conclusion about the cause of the
explosion was sound. Employing his experience and knowledge as a fire
investigator, Boh observed the physical evidence at the scene of the accident and
deduced the likely cause of the explosion. Although such a method is not
susceptible to testing or peer review, it does constitute generally acceptable
practice as a method for fire investigators to analyze the cause of fire accidents.
See Kumho Tire Co., 526 U.S. at 150 ("the relevant reliability concerns may
focus upon personal knowledge or experience"). Nothing in Rule 702 or Daubert
requires more. We conclude that the trial court did not abuse its discretion in
finding Boh's personal experience, training, method of observation, and deductive
reasoning sufficiently reliable to constitute "scientifically valid" methodology.
With regard to the testimony of Donald Sommer, as well as other experts
testifying for the Bitlers, White-Rodgers argues that his testimony constituted
impermissible speculation because he failed to test his theory that copper sulfide
particles passed through and around the mesh screen to lodge on the safety valve



seat and thereby cause the gas leak. Furthermore, White-Rodgers argues that
Sommer's theory fails to "fit" the known facts that no particles of sufficient size
to cause a leak were found on the seat of the valve. Finally, White-Rodgers
contests the reliability of the so-called "differential diagnosis" method Sommer
employed.
We turn to the issue whether the Bitlers' experts, particularly Sommer,
were required to test their theory. No doubt, Daubert noted that a key factor in
valid scientific methodology is the practice of testing hypotheses to determine
whether they can be falsified. Daubert, 509 U.S. at 593 (citing Karl Popper,
Conjectures and Refutations: The Growth of Scientific Knowledge (5th ed. 1989),
who emphasized the importance of testing scientific theories to determine whether
they can withstand critical scrutiny). One object of Popper's method of
falsification as a way of testing scientific theory is to acknowledge that any
scientific theory is subject to future refutation through further observation and
testing. Such emphasis, however, is aimed at theories purporting to explain the
causal relations among regularly occurring natural phenomena. (Ptolemy's theory
of the movement of celestial bodies which hypothesized that the Earth was the
center of the solar system, later falsified by Copernicus, is a prominent example
of such a scientific theory subject to falsification by further inquiry.) No such
theory is in question here. The Bitlers need only establish by a preponderance of



the evidence that copper sulfide particles caused a one-time occurrence Ä the gas
explosion in their basement. See, e.g., Kaiser Found. Health Plan v. Sharp, 741
P.2d 714, 719 (Colo. 1987). Their experts do not present any controversial or
novel explanations concerning regularly occurring natural phenomena.
Undoubtedly, had their experts conducted further tests on their water heater's
safety valve and established by observation that it did intermittently fail, they
would have established causation to a near certainty. But such a high degree of
certainty is not required.(2) In fact, the only phenomenon of regular occurrence at
issue here is one that is undisputed: copper sulfide particles of sufficient size or
quantity if lodged on the valve seat may cause a gas leak. Thus, because testing
is not necessary in all instances to establish reliability under Daubert, and because
it is not required by the particular factual circumstances of this case, we conclude
that the district court did not abuse its discretion in finding that the Bitlers'
experts' testimony is reliable.
With regard to White-Rodgers' argument that the Bitlers' experts
impermissibly relied on a method of "differential diagnosis," we note that the term is
being used analogically to its proper use in a medical context; nonetheless,
we conclude that in this circumstance it is a valid scientific technique to establish
causation.(3) Concerning the method he employed in his investigation, Sommer
testified that he undertook a process of eliminating alternative possible causes,
determining that these possibilities were improbable sources of the explosion, and
arriving at a highly probable cause for the gas leak, calling it a method of
"differential diagnosis." "Differential diagnosis," is "the determination of which
of two or more diseases with similar symptoms is the one from which the patient
is suffering, by a systematic comparison and contrasting of the clinical findings."
Stedman's Medical Dictionary 492 (27th ed. 1995).(4) In the medical context,
differential diagnosis is a common method of analysis, and federal courts have
regularly found it reliable under Daubert. Goebel, 346 F.3d at 999 (concluding
that a district court may admit a differential diagnosis it determines is reliable);



(2) As to alleged shortcomings of the proffered testimony, these go to "the
weight which the trier of fact should accord the evidence and do not make the
testimony incredible." Orth v. Emerson Elec. Co., 980 F.2d 632, 637 (10th Cir.
1992). Nowhere does Rule 702 or Daubert require a finding that an expert's
proffered testimony reach absolute certainty with regard to the likely truth of a
conclusion.
(3) Urging us to adopt the analysis in Stibbs v. Mapco, 945 F.Supp. 1220 (D.
Iowa 1996), which also involved a LP gas explosion implicating one of their
controls, White-Rodgers argues that the inference involved in differential
diagnosis "turns scientific analysis on its head." Id. at 1226. We reject this
reasoning as itself fundamentally unsound as we explain infra. Furthermore, we
adopt the district court's apt analysis distinguishing Stibbs on its facts from the
present case - viz., in Stibbs the plaintiff's evidence consisted of a mark on the
safety valve and the absence of a leak elsewhere, with no evidence of debris
downstream nor testimony as to how debris could have migrated past the screen.
(4) Used in its traditional medical sense, the term refers "to the diagnosis of
disease, and refers to the process of identifying external causes of diseases and
conditions as `determining cause' . . . as the circumstances warrant." Federal
Judicial Center, Reference Manual on Scientific Evidence 444 (2d ed. 2000).



Westberry v. Gislaved Gummi AB, 178 F.3d 257, 262 (4th Cir. 1999) (holding
that differential diagnosis is a reliable technique "of identifying the cause of a
medical problem by eliminating the likely causes until the most probable one is
isolated"); Clausen v. M/V New Carissa, 339 F.3d 1049, 1058-59 (9th Cir. 2003)
(recognizing differential diagnosis as a reliable method); Zuchowicz v. United
States, 140 F.3d 381, 387 (2d Cir. 1998) (upholding district court decision to
admit differential diagnosis testimony). What is not so clear is whether
"differential diagnosis" is an appropriate method when employed outside of the
medical context.
Here, however, the Bitlers' experts use a general method more aptly
characterized as a process of reasoning to the best inference.(5) The Bitlers'
experts must reason, as it were, backwards to the cause of a single explosion, and
to do so requires a process of eliminating possible causes as improbable until the
most likely one is identified. For example, Sommer and Boh both testified to how
they eliminated the gas leaks in the bedroom and the T-connector above the water
heater as likely sources of the accident; the one was not located close enough to the
source of the explosion, and the other was itself most likely the result of
trauma caused by the explosion. Sommer testified that the force of the explosion
lifted the house off its foundation, and accordingly, was the most probable cause
of the leak at the T-connector, especially in light of its damaged physical
condition. Experts must provide objective reasons for eliminating alternative
causes when employing a "differential analysis." See Clausen, 339 F.3d at 1058.
Furthermore, the inference to the best explanation must first be in the range of
possible causes; there must be some independent evidence that the cause
identified is of the type that could have been the cause. See Joiner, 522 U.S. at
146 ("[N]othing in either Daubert or the Federal Rules of Evidence requires a
district court to admit opinion evidence that is connected to existing data only by
the ipse dixit of the expert."). But more than mere possibility, an inference to the
best explanation for the cause of an accident must eliminate other possible
sources as highly improbable, and must demonstrate that the cause identified is
highly probable.(6) In the present case, it is uncontroverted that if copper sulfide
(5) Unlike a logical inference made by deduction where one proposition can
be logically inferred from other known propositions, and unlike induction where a
generalized conclusion can be inferred from a range of known particulars,
inference to the best explanation - or "abductive inferences" - are drawn about a
particular proposition or event by a process of eliminating all other possible
conclusions to arrive at the most likely one, the one that best explains the
available data.
(6) An expert must show that other causes are improbable when conducting
differential diagnosis, but "[t]his is not to say that an expert, in order to testify on
causation, must be able to categorically exclude each and every possible
alternative cause. . . ." - to require otherwise "would mean that few experts would
ever be able to testify." Stephen A. Saltzburg et al., Federal Rules of Evidence
Manual 702-33 (8th ed. 2002). Indeed, "the underlying premise of differential
diagnosis is that there is an established connection between certain possible
causes and a condition or symptomthen all of the established causes are ruledout but one."
Id. at 702-35.



particles of sufficient size became lodged on the safety valve seat, then a gas leak
substantial enough to cause the explosion in the Bitlers' basement could occur.
Whether or not that actually occurred is a question that may be answered by
inference to the best explanation.(7) We see no abuse of discretion, especially in
light of our deferential standard of review, in the district court's admitting expert
testimony that employs an expert's physical investigation, professional
experience, and technical knowledge to establish causation in this case.
Finally, as to the "fit" between the expert testimony and the material issue
at stake in this case, White-Rodgers argues that the theory of copper sulfide
particulate contamination does not "fit" the facts that the safety valve at issue is a
screened valve, and no screened valve had ever been shown to allow sufficient
copper sulfide downstream so as to cause a gas leak; furthermore, the valve
functioned properly when tested after the accident. This argument confuses a
Daubert inquiry into relevant "fit" with the jury question of which theory,
plaintiffs' or defendant's, best captures the truth of the matter at issue. The former
inquiry is aimed at determining if "a valid scientific connection to the
pertinent inquiry," Daubert, 509 U.S. at 592, obtains as a precondition to the
admissibility of expert testimony. Here, the expert testimony "fits" because it
involves a reliable method that would aid the jury in resolving a factual dispute;
whether the jury finds that the testimony "fits" their best assessment of the truth
of the matter is an altogether different issue. Accordingly, the district court did
not abuse its discretion in admitting the Bitlers' expert testimony.
Thus, in summation, we conclude that in fulfilling its gatekeeping role
pursuant to the Federal Rules of Evidence and Daubert, the district court did not
abuse its discretion in making its "preliminary assessment of whether the
reasoning or methodology underlying the testimony is scientifically valid and of
whether that reasoning or methodology properly can be applied to the facts in
issue." Daubert, 509 U.S. at 592-3.
III
White-Rodgers argues on appeal that safety valve models lacking an inlet
screen are substantially dissimilar from models containing the mesh screen and
therefore the district court abused its discretion in admitting plaintiff's evidence
of accidents involving the unscreened devices.
At trial, the Bitlers introduced evidence of accidents which involved a
(7) As Judge Kozinski noted on remand in Daubert: "Not knowing the
mechanism whereby a particular agent causes a particular effect is not always
fatal to a plaintiff's claim. Causation can be proved even when we don't know
precisely how the damage occurred, if there is sufficiently compelling proof that
the agent must have caused the damage. . . ." Daubert v. Merrell Dow Pharm., 43
F.3d 1311, 1314 (9th Cir. 1995).



model of safety valves exactly the same as the one in the Bitlers' water heater save
for the absence of the inlet screen. These accidents occurred when copper
sulfide particles contaminated the safety valve of unscreened safety controls,
preventing the valve from closing fully and resulting in a gas leak. The purpose
of this evidence was to demonstrate a key element of the Bitlers' theory of
causation: if copper sulfide particles are allowed downstream to contaminate the
valve seat, then the safety valve system could fail. Furthermore, the Bitlers argue
that this evidence was necessary to prove notice to White-Rodgers of the potential
for their safety valves to fail.
In response, White-Rodgers contends that they offered to stipulate to the
failures of the unscreened device, and that therefore the admission of evidence
involving accidents with unscreened controls was irrelevant. Although White-
Rodgers admits that copper sulphide particles can cause leaks in unscreened
models, they argue that there has been no demonstration that screened models are
susceptible to sufficient contamination to cause leaks; therefore, they suggest that
the presence of a screen makes the Bitlers' safety control substantially dissimilar
to unscreened devices. Moreover, because these other accidents involving
unscreened controls resulted in injuries and deaths, White-Rodgers argues that the
evidence was inherently prejudicial.
We review a district court's decision to admit evidence for abuse of
discretion. Smith v. Ingersoll-Rand Co., 214 F.3d 1235, 1246 (10th Cir. 2000).



As a threshold matter, we will admit evidence of prior accidents in a products
liability suit if it is relevant to the present inquiry. Id. To determine relevancy,
we must examine whether there is substantial similarity between the evidence
offered of prior accidents and the facts at issue in the present case. "Before
introducing such evidence, the party seeking its admission must show the
circumstances surrounding the other accidents were substantially similar to the
accident involved in the present case." Wheeler v. John Deere Co., 862 F.2d
1404, 1407 (10th Cir. 1988); Black v. M & W Gear Co., 269 F.3d 1220, 1227
(10th Cir. 2001). Determining whether and to what extent proffered evidence of
prior accidents involves substantially similar circumstances will depend on the
underlying theory of the case advanced by the plaintiffs. If the evidence of other
accidents is substantially similar to the accident at issue in a particular case, then
that evidence will assist the trier of fact by making the existence of a fact in
dispute more or less probable, and the greater the degree of similarity the more
relevant the evidence. See Four Corners Helicopters, Inc. v. Paton, 979 F.2d
1434, 1440 (10th Cir. 1992). Naturally, this is a fact-specific inquiry that depends
largely on the theory of the underlying defect in a particular case. Id.
Accordingly, the district court is owed considerable deference in its determination
of substantial similarity.
With regard to the Bitlers' proposed evidence of accidents involving



unscreened devices, the district court ruled that these prior accidents involved
substantially similar devices to the one involved in the present accident, and
accordingly denied the defendant's motion in limine to exclude. In order to
demonstrate notice and the existence of a defect, namely the consequences of
copper sulfide contamination, the district court ruled that exact similarity between
the devices was not required and its absence would not compel exclusion. We
have routinely held that federal law permits introduction of substantially similar
accidents to show notice, the potential existence of a defect, or to refute defense
witness testimony. Four Corners Helicopters, Inc., 979 F.2d at 1440.
In light of the plaintiffs' purposes of showing notice and defect, we do not
require a showing of exact similarity, and hence we cannot conclude that the
district court erred in admitting evidence it found substantially similar given the
circumstances surrounding the Bitlers' accident. In order to demonstrate that
copper sulfide particles were capable of causing a gas leak when contaminating
the safety valve seat, it was reasonable and relevant for the plaintiffs to introduce
evidence of failures in substantially similar devices under substantially similar
circumstances. If contamination could cause gas leaks absent an inlet screen,
then if the plaintiffs could show that particles could get through or around the
screen Ä the essence of the plaintiffs' case Ä it would be reasonable for jurors to
make a determination as to causation in the present case. Offering evidence that



the industry was aware as early as 1967 that copper sulfide contamination could
be a problem for gas control valves served the purpose of demonstrating notice to
White-Rodgers and of highlighting the potential existence of a defect Ä part of the
underlying theory of the plaintiff's case which goes to establish a standard in this
case for "how substantial the similarity must be. . . ." Ponder v. Warren Tool
Corp., 834 F.2d 1553, 1560 (10th Cir. 1987) (citation omitted). Indeed, the
district court found that the similarity between the two models of safety valves,
for purposes of the trial, was not only substantial, but constituted a "high degree
of similarity" in light of other evidence demonstrating that even with the screen,
copper sulfide particles were found downstream from the screen. (4 R. at 967.)
We see no error in the district court's finding. Accordingly, we hold that
the district court did not abuse its discretion in admitting evidence of prior
accidents involving unscreened safety valves.
IV
White-Rogers argues that the district court erred by giving a jury
instruction on failure to warn of known and non-obvious defects in its safety
valve. Whether a jury was properly instructed in accord with the applicable law
and consistent with matters properly within its provence is a question we review
de novo. Gardetto v. Mason, 100 F.3d 803, 816 (10th Cir. 1996). However, we
will review for abuse of discretion a district court's exercise of its discretion in



giving a particular jury instruction. Hynes v. Energy West, Inc., 211 F.3d 1193,
1197 (10th Cir. 2000).
Arguing that the issue of a duty to warn was not supported by the evidence,
and hence not a matter properly submitted to the jury, White-Rodgers objects to
the district court's presentation of the following instruction to the jury:
If A.O. Smith and White-Rodgers, a wholly-owned division of Emerson
Electric, as manufacturers or sellers of a product know or in the exercise of
reasonable care should know that the use of the product may be harmful or
injurious to a user, and such risk of harm or injury is not obvious to a
reasonable user, then the manufacturer and seller must use reasonable care
to warn the user of the risk of harm or injury if a reasonably careful person
would under the same or similar circumstances. The failure to do so is
negligence.

(13 R. at 3525.)

As a threshold matter, we are persuaded that White-Rodgers' assignment of
error to the district court's jury instruction on a duty to warn is not properly
preserved for appeal. At trial, White-Rodgers objected generally to the jury
instruction concerning a duty to warn, arguing only that there is neither a basis for,
nor an issue of, a failure to warn.(8) Defendant further objected that plaintiffs failed
to establish any evidence for the instruction. Rejecting White-Rodgers' inchoate
objections, the district court found "that there is evidence sufficient to allow the














(8) White-Rodgers' counsel opined generally: "If the product is found to be
defective then I guess liability exists. I don't know what we're supposed to warn
them about." (11 R. 2995.)



jury to determine that White-Rodgers knew prior to this accident of the migration
of copper sulfide around the screen only device, which the jury could conclude
required a duty to warn." (12 R. at 3057-58.)
On appeal, White-Rodgers now asserts that the jury instruction on a failure
to warn was error because plaintiffs presented no evidence of proximate causation.
Specifically, Appellant now argues that plaintiffs provided no evidence that a
warning would have been effective or what the content of that warning would have
been. However, at trial Appellants did not raise an objection as to proximate
causation distinctly and did not identify specifically the grounds of the objection
before the district court as required by Fed. R. Civ. P. 51(c)(1) ("A party who
objects to an instruction or the failure to give an instruction must do so on the
record, stating distinctly the matter objected to and the grounds of the objection.");
see also Hynes, 211 F.3d at 1200. White-Rodgers failed to make abundantly clear
the grounds and basis for its objection to the jury instruction on a failure to warn,
objecting instead in general terms that there was no issue of warning. See Weir v.
Fed. Ins. Co., 811 F.2d 1387, 1390 (10th Cir. 1987) (noting that Rule 51 "requires
counsel to make abundantly clear to the trial court the objecting party's position")
(quotation omitted). To preserve an objection for appeal, it is not enough for an
objecting party merely to raise an objection. Instead, the "grounds stated in [an]
objection must be obvious, plain, or unmistakable." Id. (citation omitted); see



also, Medlock v. Ortho Biotech, Inc., 164 F.3d 545, 553 (10th Cir. 1999) (noting
that "an excessively vague or general objection to the propriety of a given
instruction is insufficient to reserve the issue for appeal").
Accordingly, because White-Rogers' objections were not properly specific,
the issue of supposed error in the district court's jury instruction regarding failure
to warn is not properly preserved for appeal.

V
In the alternative, failing success on its argument to reverse the jury verdict,
White-Rodgers argues that the jury award of $150,000 for future wage loss and
$75,000 for future medical expenses was not supported by any evidence. When we
review a jury's award of damages, we will sustain the award unless it is clearly
erroneous or there is no evidence to support the award. Hudson v. Smith, 618 F.2d
642, 646 (10th Cir. 1980); Brown v. Presbyterian Healthcare Servs., 101 F.3d
1324, 1330 (10th Cir. 1996).
With regard to the evidence of future wage loss, Mr. Bitler provided tax
returns for the years prior and subsequent to the accident and provided testimony
concerning his current employment prospects. There is no doubt that evidence was
presented that his earnings have declined as a consequence of the accident, and
that although he remains employable in some settings, his employment prospects



have been substantially diminished. Furthermore, evidence was also offered of
benefits he received as a ranch hand, but no longer receives, such as use of the
furnished house where the accident occurred and a replacement heifer worth $850,
that go beyond his salary as reflected by his tax returns. In light of our highly
deferential stance regarding jury determinations of damages, we cannot say that
there was no evidence presented to support a jury finding of future lost wages in
the amount of $150,000.
Concerning the evidence of future medical expenses, there is no doubt that
physician testimony and Mr. Bitler's testimony did not establish precise costs of
any future procedures. One physician testifying, Dr. Hartford, described past
problems with infections involving Mr. Bitler's skin grafts, and acknowledged a
possibility of future infections. Mr. Bitler's plastic surgeon, Dr. Gordon, testified
to the future need for procedures to develop Mr. Bitler's fingernails, which Bitler
has elected to defer to a later time. (3 R. at 768.) Plaintiff argues that the jury
could reasonably estimate future medical expenses based on the stipulation by the
parties to past medical expenses. Clearly, such a basis for determining an award
for future medical expenses is imprecise and on review is not based on specific
and substantial evidence. But we do not review for substantial evidence; rather,
we review for clear error whether there is any evidence to support the jury finding.
Despite some estimation in the jury's award for future medical expenses, we



cannot conclude, in light of our deferential review, that there is no evidence to
support the award or that it was clearly erroneous.
Therefore, as to the jury awards for future wage loss and future medical
expenses, we affirm.
VI
With regard to the final issue in White-Rodgers' appeal, appellant argues
that the jury award of $25,000 for Mrs. Bitler's physical and emotional injury was
excessive. Specifically, White-Rodgers argues that negligent infliction of
emotional harm was not pled, and because Mrs. Bitler suffered only minor physical
injuries in the accident, that the jury award is clearly excessive. We disagree. As
appellant concedes, Mrs. Bitler may recover emotional injuries that flow from her
own physical injuries. See, e.g., Williams v. Continental Airlines, Inc., 943 P.2d
10, 16 (Colo. App. 1996). Because the circumstance surrounding her admittedly
minor physical injury to her knee when the force of the explosion in the basement
forced her off the sofa and onto the floor is itself quite traumatic, we cannot
conclude that the jury had no basis for finding the emotional injury associated with
her own experience of, and physical injuries from, the explosion Ä quite apart from
the emotional trauma of seeing the injuries sustained by her husband Ä are grossly
excessive. Accordingly, as to the jury's damage award for Mrs. Bitler's
negligence claim, we affirm.


VII
For the reasons set forth above, we AFFIRM.