## F I L E D 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; 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. No. 02-1527

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,2

Lampert & McClune, Broomfield, Colorado, for Plaint iffs-Appellees Fred and Peggy Bitler. Andrew M. Low (Peter J. Krumholz, with him on the b riefs), 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 wa s 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 manufact urer of the gas control installed in his basement water heater, a jury returned a ver dict 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 dist rict court, the present appeal followed. In contesting the jury verdict imposing products liability on it for the explosion, White-Rodgers assigns as principal errorthe district court’s admission of plaintiffs’ expert testimony under Daubertprinciples. We exercise jurisdiction under 28 U.S.C. § 1291 and AFFIRM

.

I Fred and Peggy Bitler resided in a house provided f or their use on the3

Oldland Ranch outside of Meeker, Colorado where Fre d Bitler was a ranch hand. On the evening of the accident, July 25, 1996, Bitl er discovered that there was no hot water when he attempted to shower. Hot water w as supplied to the Bitlers’ home by a liquid propane hot water heater located i n the basement. Donning sweat pants, he proceeded to the basement door, unl atched it, and walked approximately two-third’s of the way down the stair case 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 h ave been raised several inches by the force of the explosion. Fred Bitler sustain ed severe burns, and after being flown by helicopter to a hospital, underwent multip le skin graft surgeries over the following weeks. It was established at trial thathe 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 Bit lers’ home – a cook stove in the kitchen, a furnace in a bedroom, and aspace heater in one of the bedrooms. Gas was supplied to the water heater viaunsupported, flexible copper tubing that ran along the basement ceiling joints. A “T-fitting” was located above4

the hot water heater which provided branches runnin g to the hot water heater and the space heater. Post-accident inspection reveale d 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 w ater heater. This gas control regulates the flow of gas to the pilot and main bur ner of the water heater, and is designed to fulfill a crucial safety role if the pi lot 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 i s extinguished. As is well known, a lit pilot heats a thermocouple which in tu rn creates an electric current energizing an electromagnet that holds the safety v alve open against the force of a spring. So long as the pilot is lit, the safety va lve remains open. If the pilot goes out, however, the thermocouple will no longer be he ated and will no longer produce a current to energize the electromagnet, al lowing the spring to snap the valve shut. The safety valve seat is made of rubbe r, and is designed to create a seal against a circular metal surface when closed t o prevent the flow of gas to the pilot. Copper sulfide is a frequent contaminate found in g as 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 pre vent the valve from sealing,5

resulting in a gas leak. It was established that n umerous accidents have occurred in this manner, and that copper sulfide contaminati on 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 instal ling a wire mesh screen in the gas inlet, upstream from the safety valve to preven t copper sulfide particles from migrating onto the rubber valve seat. In further r ecognition of the safety hazard caused by copper sulfide contamination, White-Rodge rs recalled all gas controls lacking the mesh screen in 1980. Thereafter, White -Rodgers also began adding another safety feature to the mesh screen by instal ling 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 acciden t, and plaintiffs’ expert Donald Sommer concluded that the leak was caused by coppersulfide 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 engin eer and accident investigator retained by the Bitlers. Although Whi te-Rodgers contests the admissibility of these two experts on appeal, plain tiffs’ expert W. Alan6

Bullerdiek, a chemical engineer, also testified con cerning the history of copper sulfide-contamination-related accidents, and that t he amount of contamination found on the Bitlers’ safety valve seat was at an u nacceptable level. During post-accident testing of the safety valve in stalled in the Bitlers’ water heater, the device was disassembled in the pr esence of representatives of both White-Rodgers and the Bitlers. Copper sulfide particulate contamination was discovered downstream of the mesh screen and fo und on the safety valve seat. During the teardown, a test of the valve rev ealed that it snapped shut as designed. Plaintiffs’ expert, Donald Sommer, opine d 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 af ter the accident when the control was turned to the “off” position; furthermo re, 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 Co urt against White-Rodgers, as well as A.O. Smith Corporation, which manufactured the water heater, and7

National Propane Corporation, which installed and m aintained the water heater and propane piping in the house. After removing th e case to federal district court, defendants moved for summary judgment, contesting t he admission of the plaintiffs’ expert testimony as insufficiently reli able and lacking a firm foundation in science. In an order denying the mot ion, the trial judge found that the Bitlers’ proposed expert testimony was relevantand reliable in accord with the standard required by Daubert v. Merrell Dow Pha rms., Inc. , 509 U.S. 579 (1993). The matter proceeded to a two-week jury tr ial, at the close of which the jury returned a verdict against White-Rodgers and N ational 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 Bitler s. As to White-Rodgers specifically, the jury found both negligence and pr oduct defect. In its order of October 30, 2002, the district court denied White-R odgers’ motions for judgment as a matter of law and for a new trial. This appea l followed.
II We review de novo whether the district court proper ly performed its role as “gatekeeper” in admitting or excluding expert testi mony. Dodge v. Cotter Corp. , 328 F.3d 1212, 1223 (10th Cir. 2003) (“Though the d istrict court has discretion in how it conducts the gatekeeper function, we have re cognized that it has no discretion to avoid performing the gatekeeper funct ion.”). We review for abuse8

of discretion the manner in which the district court exercises its Daubert “gatekeeping” role in making decisions whether to a dmit 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 convic tion 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 tr ial court’s factual findings in pursuit of its gatekeeping role does not vary when examining exclusion or admission of expert testimony. Our fo cus on review mirrors that of the trial judge’s assessment of the testimony itsel f: 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 e xpert testimony. See Goebel , 346 F.3d at 1001 (holding that district court did n ot abuse its discretion in admitting expert testimony); Mitchell v. Gencorp In c , 165 F.3d 778, 784 (10th Cir. 1999) (holding that the district court did notabuse its discretion in excluding expert testimony). Thus, although the district cou rt “must, on the record make

some kind of reliability determination,” United States v. Velarde , 214 F.3d 1204,9

1209 (10th Cir. 2000), we recognize the wide latitu de a district court has in exercising its discretion to admit or exclude expert testimony.
A White-Rodgers assigns as a principal source of erro r the district court’s performance of its Daubertgatekeeping functions. We begin our inquiry into t he 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 evi dence 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 – whether it concerns scientific, technical, or otherspecial knowledge – has “a reliable basis in the knowledge and experience of h is [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 u nder Rule 702). By conducting a preliminary inquiry into the expert’s qualifications and the admissibility of proffered evidence, a district cou rt fulfills its initial obligation under Fed. R. Evid. 104(a) (“Preliminary questions concerning the qualification of a person to be a witness . . . or the admissibil ity of evidence shall be determined by the court”). To determine whether expert testimony is admissible10

requires a trial court to examine “whether the reas oning 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 und isputably 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 reli ability 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 su ggested that a court consider: (1) whether a theory has been or can be t ested or falsified, (2) whether the theory or technique has been subject to peer re view and publication, (3) whether there are known or potential rates of errorwith 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, ho wever, 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 rele vant in the context of a new and novel scientific theory – asking if it has been tested, subjected to peer review and publication, etc. – they do provide examples of the general kinds of issues a1 Determining whether proffered testimony is scient ifically reliable can be

a considerable challenge for a trial judge. As Jus tice Breyer has noted, “this requirement will sometimes ask judges to make subtl e and sophisticated determinations about scientific methodology and its relation to the conclusions an expert witness seeks to offer – particularly when acase arises in an area where the science itself is tentative or uncertain. . . . ” Joiner , 522 U.S. at 147-48 (continued...) 11 trial court need probe in light of its purpose of e nsuring that an expert “employs in the courtroom the same level of intellectual rig or 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, albeitsuggestive, will not be dispositive of a district court’s failure to fulfil l its gatekeeping role because that role depends on the underlying factual circumstance s 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 metho dology 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 exis ts 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 relation1 (...continued)

(Breyer, J., concurring). To fulfill this task, ho wever, as Judge Posner has observed, “we do not have to become philosophers of science and set forth the necessary and sufficient conditions of ‘real’ scien ce,” or endeavor to discover “the essence of ‘science,’ if there is such an esse nce.” Rosen v. Ciba-Geigy Corp. , 78 F.3d 316, 318 (7th Cir. 1996). We may leave t he philosophy of science to the philosophers. 12 between an expert’s method, the proffered conclusio ns, and the particular factual circumstances of the dispute, and not asymptotic pe rfection, that renders testimony both reliable and relevant. Second, in fulfilling its Daubertobligations a trial court must also conduct a further inquiry into whether proposed testimony i s sufficiently “relevant to the task at hand.” Daubert , 509 U.S. at 597. Relevant evidence “means eviden ce having any tendency to make the existence of any fa ct that is of consequence to the determination of the action more probable or le ss probable than it would be without the evidence.” Fed. R. Evid. 401. The Sup reme 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 b etween 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 approp riately 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 of13

quantum mechanics may be scientifically relevant, b ut 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 Daubertgatekeeping function, the district court, in its o rder denying summary judgment to the defendants, focused on two expert witnesses proposed by the Bitlers: Elden Boh and Donald Somm er. 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 dep ositions as analyzed by the district court on motions for summary judgment. No netheless White-Rodgers argues that the magistrate judge was required to pe rform a gatekeeping role by entertaining anew, during pre-trial proceedings, de fendant’s objections to the testimony of Sommer; the magistrate judge instead t reated 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, t he district court did not fail to perform its Daubertrole merely by refusing to reconsider the question of14

admissibility that had already been decided. Daube rtdoes 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 di strict court specifically found that Boh’s methodology in reaching his conclu sion about the cause of the explosion was sound. Employing his experience and knowledge as a fire investigator, Boh observed the physical evidence atthe scene of the accident and deduced the likely cause of the explosion. Althoug h such a method is not susceptible to testing or peer review, it does cons titute generally acceptable practice as a method for fire investigators to anal yze the cause of fire accidents.
See Kumho Tire Co. , 526 U.S. at 150 (“the relevant reliability concer ns may focus upon personal knowledge or experience”). Not hing in Rule 702 or Daubert requires more. We conclude that the trial court di d not abuse its discretion in finding Boh’s personal experience, training, method of observation, and deductive reasoning sufficiently reliable to constitute “scie ntifically valid” methodology. With regard to the testimony of Donald Sommer, as w ell as other experts testifying for the Bitlers, White-Rodgers argues th at his testimony constituted impermissible speculation because he failed to testhis theory that copper sulfide particles passed through and around the mesh screento lodge on the safety valve15

seat and thereby cause the gas leak. Furthermore, White-Rodgers argues that Sommer’s theory fails to “fit” the known facts thatno 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 “differen tial diagnosis” method Sommer employed. We turn to the issue whether the Bitlers’ experts, particularly Sommer, were required to test their theory. No doubt, Daub ertnoted that a key factor in valid scientific methodology is the practice of tes ting hypotheses to determine whether they can be falsified. Daubert , 509 U.S. at 593 (citing Karl Popper, Conjectures and Refutations: The Growth of Scientif ic 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 a scientific theo ry is to acknowledge that any scientific theory is subject to future refutation t hrough further observation and testing. Popper’s emphasis, however, is aimed at t heories purporting to explain the causal relations among regularly occurring natu ral 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 fals ification by further inquiry.) Although we would not conclude from the citation to Popper, or the logical16

positivist Carl Hempel, id. at 593, that the Supreme Court intended to limit a district court’s consideration of whether testing w ould assist the trier of fact only to those instances of scientific knowledge aimed atsuch causal relations, we do find the emphasis suggested by the citations instru ctive. For example, in Truck Ins. Exch. v. Magnetek Inc. , 360 F.3d 1206, 1211- 1212 (10th Cir. 2004), plaintiff attempted to intro duce evidence of a novel theory, “pyrolysis,” which hypothesized that wood could ign ite at temperatures much lower than normal under particular circumstances. We affirmed the district court’s decision to exclude this evidence because p laintiff’s experts had failed to test their novel theory sufficiently to demonstrate its scientific reliability. Id. at 1213. When an expert proposes a theory that modifi es otherwise well-established knowledge about regularly occurring phenomenon, suc h as the normal ignition temperature of wood, we would expect the importance of testing as a factor in determining reliability to be at its highest. Here , by contrast, plaintiffs’ experts propose a theory about how the accident occurred gi ven the known science of copper sulfide particulate contamination as a cause of propane gas leaks. What distinguishes the present case is that the need fortesting is not at its highest because the reliability of the science of copper su lfide contamination is not in dispute, and thus the district court did not abuse its discretion in finding that the presence of a screen did not alter the reliability of the fundamental science.17

Whether the Bitlers established that the copper sul fide particles and grease found on the valve seat caused this accident is a m atter the district court determined goes to the sufficiency of the evidence – not its scientific reliability. Defendants misunderstand what is at stake in a reli ability analysis when they claim that the mere addition of a screen fundamenta lly and necessarily changed the nature of the underlying science such that the district court abused its discretion in admitting plaintiffs’ expert testimony. No doubt, presence of the screen changed the causal analysis the jury was req uired to conduct based on the conflicting evidence presented, but the presence of a screen did not change the analysis into one that necessarily required furthertesting to determine its scientific reliability. The core science – that co pper sulfide particles are the kind of thing that when lodged on the valve seat can cau se leaks – is sufficiently wellestablished that the district court did not abuse i ts discretion in finding it reliable. The core dispute – whether copper sulfide particles found on the valve seat in this case were sufficient to cause a leak – is one the d istrict court could properly determine is a question for the jury. In light of this evidentiary dispute, the Bitlers need only establish by a preponderance of t he evidence that copper sulfide particles caused the gas explosion in their basemen t. See, e.g. , Kaiser Found. Health Plan v. Sharp , 741 P.2d 714, 719 (Colo. 1987). Had their expert s conducted further tests on their water heater’s saf ety valve and established by2 As to alleged shortcomings of the proffered testi mony, these go to “the

weight which the trier of fact should accord the ev idence 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 Daubertrequire a finding that an expert’s proffered testimony reach absolute certainty with r egard to the likely truth of a conclusion. See Daubert , 509 U.S. at 590 (“Of course, it would be unreason able to conclude that the subject of scientific testimony must be ‘known’ to a certainty; arguably, there are no certainties in science.”).

3 Urging us to adopt the analysis in Stibbs v. Mapc o , 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 i nvolved in differential diagnosis “turns scientific analysis on its head.” Id . at 1226. We reject this reasoning as itself fundamentally unsound as we exp lain infra . Furthermore, we adopt the district court’s apt analysis distinguish ing Stibbs on its facts from the present case – viz., in Stibbs the plaintiff’s evidence consisted of a mark on th e safety valve and the absence of a leak elsewhere, w ith no evidence of debris (continued...) 18 observation that it did intermittently fail, they m ay have established causation to a near certainty. But such a high degree of certainty is not required. 2 Thus, because testing is not necessary in all instances t o establish reliability under Daubert , and because the district court reasonably found t hat it was not required by the particular factual circumstances of this cas e, we conclude that the district court did not abuse its discretion in admitting the Bitlers’ experts’ testimony. With regard to White-Rodgers’ argument that the Bit lers’ experts impermissibly relied on a method of “differential d iagnosis,” we note that the term is being used analogically to its proper use i n 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 investig ation, Sommer3 (...continued)

downstream nor testimony as to how debris could hav e migrated past the screen.

4 Used in its traditional medical sense, the term r efers “to the diagnosis of disease, and refers to the process of identifying e xternal causes of diseases and conditions as ‘determining cause’ . . . as the circ umstances warrant.” Federal Judicial Center, Reference Manual on Scientific Evi dence 444 (2d ed. 2000). 19 testified that he undertook a process of eliminatin g alternative possible causes, determining that these possibilities were improbabl e sources of the explosion, and arriving at a highly probable cause for the gas lea k, calling it a method of “differential diagnosis.” “Differential diagnosis, ” is “the determination of which of two or more diseases with similar symptoms is th e one from which the patient is suffering, by a systematic comparison and contra sting of the clinical findings.” Stedman’s Medical Dictionary492 (27th ed. 1995). 4 In the medical context, differential diagnosis is a common method of analys is, 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 diag nosis it determines is reliable); 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 un til 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 m ethod); Zuchowicz v. United
States , 140 F.3d 381, 387 (2d Cir. 1998) (upholding distr ict court decision to5 Unlike a logical inference made by deduction wher e 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 i nferences” – are drawn about a particular proposition or event by a process of eli minating all other possible conclusions to arrive at the most likely one, the o ne that best explains the available data. 20 admit differential diagnosis testimony). What is n ot so clear is whether “differential diagnosis” is an appropriate method w hen employed outside of the medical context. Here, however, the Bitlers’ experts use a general m ethod more aptly characterized as a process of reasoning to the bestinference. 5 The Bitlers’ experts must reason, as it were, backwards to the c ause 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, Sommerand Boh both testified to how they eliminated the gas leaks in the bedroom and th e T-connector above the water heater as likely sources of the accident; the one w as not located close enough to the source of the explosion, and the other was itse lf most likely the result of trauma caused by the explosion. Sommer testified t hat the force of the explosion lifted the house off its foundation, and accordingl y, was the most probable cause of the leak at the T-connector, especially in lightof its damaged physical condition. Experts must provide objective reasons for eliminating alternative causes when employing a “differential analysis.” S ee Clausen , 339 F.3d at 1058.6 An expert must show that other causes are improba ble when conducting

differential diagnosis, but “[t]his is not to say t hat an expert, in order to testify on causation, must be able to categorically exclude ea ch and every possible alternative cause. . . .” – to require otherwise “w ould 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 pr emise of differential diagnosis is that there is an established connectio n between certain possible causes and a condition or symptom—then all of the e stablished causes are ruled out but one.” Id . at 702–35.

7 As Judge Kozinski noted on remand in Daubert : “Not knowing the mechanism whereby a particular agent causes a parti cular effect is not always fatal to a plaintiff’s claim. Causation can be pro ved even when we don’t know (continued...) 21 Furthermore, the inference to the best explanation must first be in the range of possible causes; there must be some independent evi dence 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 Daubertor the Federal Rules of Evidence requires a district court to admit opinion evidence that is co nnected to existing data only by the ipse dixit of the expert.”). But more than mer e 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 particles of sufficient size became lodged on the s afety valve seat, then a gas leak substantial enough to cause the explosion in the Bi tlers’ 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 in7 (...continued)

precisely howthe damage occurred, if there is sufficiently comp elling proof that the agent must have caused the damage. . . .” Daube rt v. Merrell Dow Pharm. , 43 F.3d 1311, 1314 (9th Cir. 1995). 22 light of our deferential standard of review, in the district court’s admitting expert testimony that employs an expert’s physical investi gation, professional experience, and technical knowledge to establish ca usation in this case. Finally, as to the “fit” between the expert testimo ny and the material issue at stake in this case, White-Rodgers argues that th e 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 Daubertinquiry 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” th eir best assessment of the truth of the matter is an altogether different issue. Ac cordingly, the district court did23

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 Daube rt , the district court did not abuse its discretion in making its “preliminary ass essment of whether the reasoning or methodology underlying the testimony i s 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 mo dels lacking an inlet screen are substantially dissimilar from models con taining 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 accide nts which involved a model of safety valves exactly the same as the one in the Bitlers’ water heater save for the absence of the inlet screen. These ac cidents occurred when copper sulfide particles contaminated the safety valve of unscreened safety controls, preventing the valve from closing fully and resulti ng in a gas leak. The purpose of this evidence was to demonstrate a key element o f 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 argue24

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 offer ed to stipulate to the failures of the unscreened device, and that therefo re the admission of evidence involving accidents with unscreened controls was irrelevant. Although WhiteRodgers admits that copper sulphide particles can c ause leaks in unscreened models, they argue that there has been no demonstration that screened models are susceptible to sufficient contamination to cause le aks; therefore, they suggest that the presence of a screen makes the Bitlers’ safety control substantially dissimilar to unscreened devices. Moreover, because these oth er 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 evid ence 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 pr ior accidents in a products liability suit if it is relevant to the present inq uiry. Id . To determine relevancy, we must examine whether there is substantial simila rity between the evidence offered of prior accidents and the facts at issue i n the present case. “Before introducing such evidence, the party seeking its ad mission must show the circumstances surrounding the other accidents were substantially similar to the25

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 circ umstances will depend on the underlying theory of the case advanced by the plain tiffs. 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 maki ng 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 inq uiry that depends largely on the theory of the underlying defect in aparticular case. Id

. Accordingly, the district court is owed considerabl e deference in its determination of substantial similarity. With regard to the Bitlers’ proposed evidence of ac cidents involving unscreened devices, the district court ruled that t hese prior accidents involved substantially similar devices to the one involved i n 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, n amely the consequences of copper sulfide contamination, the district court ru led that exact similarity between the devices was not required and its absence would not compel exclusion. We26

have routinely held that federal law permits introd uction of substantially similar accidents to show notice, the potential existence o f 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 not ice 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. I n order to demonstrate that copper sulfide particles were capable of causing a gas leak when contaminating the safety valve seat, it was reasonable and releva nt for the plaintiffs to introduce evidence of failures in substantially similar devic es under substantially similar circumstances. If contamination could cause gas le aks absent an inlet screen, then if the plaintiffs could show that particles co uld get through or around the screen – the essence of the plaintiffs’ case – it w ould be reasonable for jurors to make a determination as to causation in the presentcase. Offering evidence that the industry was aware as early as 1967 that coppersulfide contamination could be a problem for gas control valves served the purp ose of demonstrating notice to White-Rodgers and of highlighting the potential exi stence of a defect – part of the underlying theory of the plaintiff’s case which goe s 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 om itted). Indeed, the27

district court found that the similarity between th e 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 fromthe screen. (4 R. at 967.) We see no error in the district court’s finding. A ccordingly, 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 b y giving a jury instruction on failure to warn of known and non-obv ious defects in its safety valve. Whether a jury was properly instructed in a ccord with the applicable law and consistent with matters properly within its pro vence 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. Ene rgy 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 ju ry, 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 div ision of Emerson Electric, as manufacturers or sellers of a product know or in the exercise of8 White-Rodgers’ counsel opined generally: “If the product is found to be

defective then I guess liability exists. I don’t k now what we’re supposed to warn them about.” (11 R. 2995.) 28 reasonable care should know that the use of the pro duct 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 m ust use reasonable care to warn the user of the risk of harm or injury if areasonably 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 aduty to warn is not properly preserved for appeal. At trial, White-Rodgers obje cted 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. Rej ecting White-Rodgers’ inchoate objections, the district court found “that there is evidence sufficient to allow the jury to determine that White-Rodgers knew prior to this accident of the migration of copper sulfide around the screen only device, wh ich 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 e vidence of proximate causation. Specifically, Appellant now argues that plaintiffs provided no evidence that a29

warning would have been effective or what the conte nt of that warning would have been. However, at trial Appellants did not raise a n objection as to proximate causation distinctly and did not identify specifica lly the grounds of the objection before the district court as required by Fed. R. Ci v. 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 a nd the grounds of the objection.”);

see also Hynes , 211 F.3d at 1200. White-Rodgers failed to make a bundantly 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 n o issue of warning. See Weir v. Fed. Ins. Co. , 811 F.2d 1387, 1390 (10th Cir. 1987) (noting thatRule 51 “requires counsel to make abundantly clear to the trial courtthe 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. Inst ead, 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 fo r 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.30 V In the alternative, failing success on its argumentto reverse the jury verdict, White-Rodgers argues that the jury award of $150,00 0 for future wage loss and $75,000 for future medical expenses was not support ed by any evidence. When we review a jury’s award of damages, we will sustain t he award unless it is clearly erroneous or there is no evidence to support the aw ard. Hudson v. Smith , 618 F.2d 642, 646 (10th Cir. 1980); Brown v. Presbyterian He althcare 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 a ccident and provided testimony concerning his current employment prospects. There is no doubt that evidence was presented that his earnings have declined as a cons equence of the accident, and that although he remains employable in some setting s, his employment prospects have been substantially diminished. Furthermore, e vidence was also offered of benefits he received as a ranch hand, but no longerreceives, such as use of the furnished house where the accident occurred and a r eplacement heifer worth $850, that go beyond his salary as reflected by his tax r eturns. 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 f inding of future lost wages in the amount of $150,000.31

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, D r. Hartford, described past problems with infections involving Mr. Bitler’s ski n grafts, and acknowledged a possibility of future infections. Mr. Bitler’s pla stic surgeon, Dr. Gordon, testified to the future need for procedures to develop Mr. Bi tler’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 b ased 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 rev iew is not based on specific and substantial evidence. But we do not review forsubstantial evidence; rather, we review for clear error whether there is any evid ence to support the jury finding. Despite some estimation in the jury’s award for fut ure 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 lo ss and future medical expenses, we affirm.
VI With regard to the final issue in White-Rodgers’ ap peal, appellant argues that the jury award of $25,000 for Mrs. Bitler’s physical and emotional injury was32

excessive. Specifically, White-Rodgers argues thatnegligent infliction of emotional harm was not pled, and because Mrs. Bitle r suffered only minor physical injuries in the accident, that the jury award is cl early excessive. We disagree. As appellant concedes, Mrs. Bitler may recover emotion al 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 itsel f 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 – quite apart from the emotional trauma of seeing the injuries sustain ed by her husband – are grossly excessive. Accordingly, as to the jury’s damage aw ard for Mrs. Bitler’s negligence claim, we affirm.
VII For the reasons set forth above, we AFFIRM

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