Opinion ID: 781962
Heading Depth: 2
Heading Rank: 2

Heading: Dodge II — Admissibility of Expert Testimony

Text: 21 In Dodge II, Cotter raises two issues regarding the admissibility of plaintiffs' experts. First, Cotter argues that the district court failed to perform the gatekeeper function mandated by Daubert by focusing its findings entirely on certain experts' professional qualifications and failing to make specific findings relating to the reliability of their opinions. Second, Cotter argues that had the district court performed its gatekeeper function, it would have excluded as unreliable the testimony of certain plaintiffs' experts, including geologist Glen Miller and medical experts Dr. Malin Dollinger and Dr. Martyn Smith. Dodge II Aplt. Br. at 22. Cotter does not challenge the experts' credentials, expertise or qualifications to testify as experts in their respective areas of concern. 22 It is by now well established that Fed.R.Evid. 702 imposes on a district court a gatekeeper obligation to ensure that any and all scientific testimony or evidence admitted is not only relevant, but reliable. Daubert, 509 U.S. at 589, 113 S.Ct. 2786. This gatekeeper function requires the judge to assess the reasoning and methodology underlying the expert's opinion, and determine whether it is both scientifically valid and applicable to a particular set of facts. Id. at 592-93, 113 S.Ct. 2786. The Supreme Court has made clear that `where [expert] testimony's factual basis, data, principles, methods, or their application are called sufficiently into question ... the trial judge must determine whether the testimony has `a reliable basis in the knowledge and experience of [the relevant] discipline.' Kumho Tire Co. v. Carmichael, 526 U.S. 137, 149, 119 S.Ct. 1167, 143 L.Ed.2d 238 (1999) (quoting Daubert, 509 U.S. at 592, 113 S.Ct. 2786). 23 To be reliable under Daubert, an expert's scientific testimony must be based on scientific knowledge, which implies a grounding in the methods and procedures of science based on actual knowledge, not subjective belief or unsupported speculation. 509 U.S. at 590, 113 S.Ct. 2786. In other words, an inference or assertion must be derived by the scientific method ... [and] must be supported by appropriate validation — i.e. `good grounds,' based on what is known. Id. While expert opinions must be based on facts which enable [the expert] to express a reasonably accurate conclusion as opposed to conjecture or speculation, ... absolute certainty is not required. Gomez v. Martin Marietta Corp., 50 F.3d 1511, 1519 (10th Cir.1995) (quotation omitted). The plaintiff need not prove that the expert is undisputably correct or that the expert's theory is `generally accepted' in the scientific community. Mitchell v. Gencorp Inc., 165 F.3d 778, 781 (10th Cir.1999). 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 satisfy Rule 702's reliability requirements. Id. 24 To assist in the assessment of reliability, the Supreme Court in Daubert listed four nonexclusive factors that the trial court may consider: (1) whether the opinion at issue is susceptible to testing and has been subjected to such testing; (2) whether the opinion has been subjected to peer review; (3) whether there is a known or potential rate of error associated with the methodology used and whether there are standards controlling the technique's operation; and (4) whether the theory has been accepted in the scientific community. 509 U.S. at 593-94, 113 S.Ct. 2786. As noted, the list is not exclusive, and district courts applying Daubert have broad discretion to consider a variety of other factor. Kumho Tire, 526 U.S. at 150, 119 S.Ct. 1167 ([W]e can neither rule out, nor rule in, for all cases and for all time the applicability of the factors mentioned in Daubert .... Too much depends upon the particular circumstances of the particular case at issue.). 25 Generally, the district court should focus on an expert's methodology rather than the conclusions it generates. Daubert, 509 U.S. at 595, 113 S.Ct. 2786. However, an expert's conclusions are not immune from scrutiny: A court may conclude that there is simply too great an analytical gap between the data and the opinion proffered. General Elec. Co. v. Joiner, 522 U.S. 136, 146, 118 S.Ct. 512, 139 L.Ed.2d 508 (1997) ([N]othing in either Daubert or the Federal Rules of Evidence requires a district court to admit opinion evidence which is connected to existing data only by the ipse dixit of the expert.). Under Daubert, any step that renders the analysis unreliable ... renders the expert's testimony inadmissible. This is true whether the step completely changes a reliable methodology or merely misapplies that methodology. Mitchell, 165 F.3d at 782 (quoting In re Paoli R.R. Yard PCB Litigation, 35 F.3d 717, 745 (3d Cir.1994)). It is critical that the district court determine whether the evidence is genuinely scientific, as distinct from being unscientific speculation offered by a genuine scientist. Id. at 783 (quoting Rosen v. Ciba-Geigy Corp., 78 F.3d 316, 318 (7th Cir.1996)). Regardless of the specific factors at issue, the purpose of the Daubert inquiry is always to make certain that an expert, whether basing testimony upon professional studies or personal experience, 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, 119 S.Ct. 1167.
26 We review de novo the question of whether the district court applied the proper legal test in admitting an expert's testimony. Goebel v. Denver & Rio Grande W. R.R. Co., 215 F.3d 1083, 1087 (10th Cir.2000). 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. Id. (citing Kumho Tire, 526 U.S. at 158-59, 119 S.Ct. 1167 (Scalia, J., concurring)). Therefore, we review de novo the question of whether the district court applied the proper standard and actually performed its gatekeeper role in the first instance. We then review the trial court's actual application of the standard in deciding whether to admit or exclude an expert's testimony for abuse of discretion. Joiner, 522 U.S. at 139, 118 S.Ct. 512. The trial court's broad discretion applies both in deciding how to assess an expert's reliability, including what procedures to utilize in making that assessment, as well as in making the ultimate determination of reliability. Kumho Tire, 526 U.S. at 152, 119 S.Ct. 1167; United States v. Velarde, 214 F.3d 1204, 1208-09 (10th Cir.2000). Accordingly, we will not disturb the district court's ruling unless it is arbitrary, capricious, whimsical or manifestly unreasonable or when we are convinced that the district court made a clear error of judgment or exceeded the bounds of permissible choice in the circumstances. Atlantic Richfield Co. v. Farm Credit Bank of Wichita, 226 F.3d 1138, 1163-64 (10th Cir.2000). 27 A natural requirement of the gatekeeper function is the creation of a sufficiently developed record in order to allow a determination of whether the district court properly applied the relevant law. Goebel, 215 F.3d at 1087; see also Dodge I, 203 F.3d at 1200 n. 12 (urging the district court on remand to vigilantly make detailed findings to fulfill the gatekeeper role crafted in Daubert  to ensure that each particular opinion is based on valid reasoning and reliable methodology). In Velarde, we observed that  Kumho and Daubert make it clear that the [district] court must, on the record, make some kind of reliability determination. 214 F.3d at 1209. Thus, we held in Goebel that when faced with a party's objection, a district court must adequately demonstrate by specific findings on the record that it has performed its duty as gatekeeper. 215 F.3d at 1088 (emphasis added). Without specific findings or discussion on the record, it is impossible on appeal to determine whether the district court carefully and meticulously reviewed the proffered scientific evidence or simply made an off-the-cuff decision to admit the expert testimony. Id. (quotations omitted). In the absence of such findings, we must conclude that the court abused its discretion in admitting such testimony. Id.
28
29 Before trial, Cotter moved to exclude the testimony of certain plaintiffs' experts on the grounds that the opinions were not reliable under Daubert. Aplt.App. at 002034-101. The 47-page motion included an appendix of several thousand pages containing Fed.R.Civ.P. 26 reports from both parties' experts, deposition testimony, and over 200 articles and studies relied upon by the experts. Id. at 002103-009852. Concluding that the motion violated local court rules regarding length, the district court returned the motion and accompanying appendix and allowed Cotter to file a revised motion and appendix, neither of which could exceed 20 pages in length. Id. at 009857-858. Cotter moved for leave to submit a lengthier appendix to provide the court with sufficient information to make its ultimate determination, id. at 009860-862, but the district court denied the motion, finding that such material is prolix because the 20-page limit is sufficient to allow [Cotter] to allege that plaintiffs' experts are not, in fact, experts, or that they base their opinions on unreliable studies or methodologies. Id. at 009865. Cotter then submitted a revised motion and appendix complying with the limits in which Cotter objected to the reliability of six of the plaintiffs' proposed expert witnesses. Id. at 009868-908. 30 The district court recognized the necessity of conducting a Daubert hearing to address several important issues raised in the motions. Id. at 010114. At a trial preparation conference, the court informed the parties that its Daubert rulings are going to be very similar, if not the same, as [its] rulings were [in Dodge I ] ... except in the areas where the Court of Appeals [found] error. Id. The district court also informed the parties that while it wished to conduct the Daubert hearing without live witness testimony by relying on argument and proffers, it would consider allowing live witnesses if absolutely necessary. Id. at 010166. Plaintiffs submitted several proffers in opposition to Cotter's Daubert motion including summaries of their challenged experts' opinions, bases, methods and conclusions. Id. at 010191-271, 299-307. Cotter also submitted exhibits including expert affidavits, deposition testimony, articles, studies and proffers related to the contested experts. Id. at 010330-696. 31
32 At the Daubert hearing, Cotter stated its intention to introduce live testimony from three of its experts. Id. at 010700. Citing Cotter's failure to notify the court of this intention in a timely manner, the court refused to allow any live witness testimony. Id. at 010704. Thus, relying solely on evidentiary proffers, each party argued its position on the admissibility of certain expert testimony. Id. at 010698-843. Three experts in particular were the focus of Cotter's argument. The first was geologist Glen Miller, whose expert testimony would be offered to establish the presence of harmful substances (i.e., uranium, molybdenum, arsenic, lead) in levels exceeding the natural background in soil, water and vegetation samples taken in and around plaintiffs' properties and also to establish that such substances derived from the Mill. Id. at 010755-782. The remaining two were Dr. Malin Dollinger, a medical doctor board certified in internal medicine and oncology, and Martyn Smith, Ph.D., a professor of toxicology; the testimony from these experts would be offered to establish that the harmful substances released from the Mill were a cause of plaintiffs' extensive range of maladies. Id. at 010706-726. 33 Briefly summarized, Cotter argued that Mr. Miller's testimony was unreliable due to his use of unreliable methodologies, specifically the method and reasoning he employed in selecting baselines with which to compare the measured levels of the substances at issue. Because each of these substances are naturally found in the environment, and because the vicinity of the Mill was known to be mineral rich and geologically varied, Cotter argued that the selection of valid baselines was nothing short of fundamental to determining if Cotter was in fact responsible for the measured levels of the substances on plaintiffs' properties. Cotter took particular issue with Mr. Miller's use of baselines from a textbook published in 1966, referred to by the author's name, Bowen, which established worldwide average baselines of various substances. Although Mr. Miller maintained that no superior source of pre-Mill-contamination baselines were available, Cotter argued, among other things, that use of Bowen's worldwide baselines, as opposed to baselines more directly tied to the specific mineral-rich vicinity of the Mill, rendered Mr. Miller's entire analysis unreliable. Id. at 010755-782. 34 Cotter also argued that the causation testimony from Drs. Dollinger and Smith was unreliable due to their reliance on improper methodology and reasoning to conclude that substances from Cotter caused the plaintiffs' maladies. Specifically, Cotter took issue with: (1) their reliance on Mr. Miller's testimony to conclude that plaintiffs were significantly exposed without any real understanding or estimate of dose or exposure amounts; (2) their conclusion without proper scientific support that the substances at issue could even cause health problems in humans like those alleged by plaintiffs; and (3) the reasoning that because nothing else seemed to account for the plaintiffs' alleged maladies, contamination from Cotter must have been the cause. 35 The district court recognized that several of Cotter's arguments merited close attention. Id. at 010839-840. The court specifically expressed concern with various aspects of the proposed expert testimony, including Mr. Miller's baselines for dust, vegetation and water. Id. at 010786, 010770-771, 010792-795, 010801, 010804, 010809-811. In fact, the court had the following to say regarding perceived problems with Mr. Miller's testimony: 36 Let me just be very candid with you. I wish that the plaintiffs had some better information on background. I think it would be much better if they had; if they had even gone out and done some tests in the surrounding areas, rather than rely on Bowen. What is the level in Europe or Israel or South Africa, it seems to me is not that critical. 37 Unfortunately, they didn't. Now, if I don't give Mr. Miller a chance to show that this background is sufficient, basically the whole plaintiffs' case goes and we might as well just strike the trial. And I frankly don't want to do that. I think the plaintiffs should have some opportunity to present their case to the jury. 38 Id. at 010817. Recognizing the need to hear from the experts themselves, the court opted to reserve ruling on each expert until trial, at which time the court would allow in camera voir dire of each contested expert. Id. at 010839-840. As a result, at the Daubert hearing, the court made no specific findings on the record concerning the reliability of the experts' testimony. Id. at 010840. The court concluded the hearing by denying Cotter's request to proffer a complete appendix of the reports and studies relied upon by the contested experts, stating that it would ask for any additional materials if it needed them. Id. at 010842. 39
40 Upon reviewing the record, we reluctantly conclude that the district court did not perform its gatekeeper function with respect to plaintiffs' experts Mr. Miller, Dr. Dollinger and Dr. Smith and thereby abused its discretion by admitting their testimony. Faced with an exceedingly difficult, complex case and obvious docket pressures, the court did not make adequate findings on the record to assure that the expert testimony offered was both relevant and reliable, and that the particular opinions were based on valid reasoning and reliable methodology. 41 As is true in most any toxic tort action, the outcome of this case indisputably hinges on the testimony of experts. Recognizing this fact, in reversing and remanding Dodge I, we specifically alerted the district court to the fundamental importance of properly performing the gatekeeper function: 42 [B]ecause the question of expert testimony is likely to recur, we would be remiss not to indicate our concern that the district court vigilantly make detailed findings to fulfill the gatekeeper role crafted in Daubert .... Given the novelty of the medical causation theory here linking exposure to molybdenum with osteoarthritis and bony exostoses, it is essential that by specific findings of record the trial court assures the expert testimony offered by both sides is relevant and reliable, and the particular opinion is based on valid reasoning and reliable methodology. 43 203 F.3d at 1200 n. 12 (quotations omitted) (emphasis added). At the Daubert hearing itself, the district court made no specific, detailed findings on the record concerning any of the experts' testimony. Therefore, unless the court made such findings at trial during the in camera voir dire of Mr. Miller, Dr. Dollinger, and Dr. Smith, it necessarily failed to perform the gatekeeper function with respect to those experts. 44 Regarding Mr. Miller, after a brief in camera voir dire by the parties, the court made the following findings, which we include in their entirety: 45 There certainly are problems here, a lot of problems, concerning water, concerning vegetation, and the differences. But what I have heard is that Mr. Miller is certainly a well-qualified geologist, got his degree in Wyoming, has a great deal of experience. 46 He wishes to use Bowen, which is a source or a treatise widely accepted by state agencies. He also has looked at the Southfield Mine and the values there. He has looked at many other sources, baselines and GeoTrans, and the USGS figures. 47 I think that the problems that exist with differences can be covered by cross-examination. And with one exception, I'm going to permit him to testify. I'd like to hear what he says. I'd like to hear the direct and cross. If there are any huge problems, I'd like to hear a Rule 50 motion at the end of the case. 48 But the one problem I have is the dust. There apparently is no baseline for dust. It's not in Bowen, and the Court feels that it's just speculation to let this witness testify about dust. And he may not testify concerning dust. 49 As far as the water, vegetation, soil, et cetera, I think that can be covered on cross-examination. 50 Aplt.App. at 012035-036. These findings lack the degree of specificity that would allow us to determine whether the district court properly applied the relevant law. Not only is no mention made about Mr. Miller's reasoning or the reliability of his methodology, no mention is made at all about how or why he arrived at his conclusion that the Bowen text was the proper source to establish baselines for the area in question. Having reviewed the record, we certainly share the district court's obvious concern about Mr. Miller's selection of baseline values. See, e.g., id. at 010817-818. However, in the absence of specific, detailed findings, it is impossible for us on appeal to determine whether the district court carefully and meticulously reviewed the proffered scientific evidence or simply made an off-the-cuff decision to admit the expert testimony. Goebel, 215 F.3d at 1088 (quotations omitted). 51 Regarding the causation testimony presented by Dr. Dollinger and Dr. Smith, the court likewise did not make adequate findings on the record to assure that the testimony offered was relevant and reliable, and that the particular opinions were based on valid reasoning and reliable methodology. In their entirety, the court's findings relating to Dr. Dollinger are as follows: 52 What the Court is faced with is an expert witness in internal medicine and the subspecialty of oncology who has a very fine education — Yale medical school, Phi Beta Kappa — and other excellent background; who treats patients with cancer and other diseases; who has reviewed medical literature on the effects of molybdenum, lead, arsenic, uranium, on human beings, heavy metals; who perhaps is going to disagree with defendant's experts on many of these areas. But just because Dr. Dollinger's view may be a minority view or different from defendant's does not mean that he is not qualified as an expert opinion in the area of internal medicine, oncology, to — to give testimony on whether or not different heavy metals are substantial causes of whatever the ailments are. 53 Now, I will take objections as we go along; and if something appears to be far afield from his specialty, I will consider the objection of Counsel. 54 But right now, we have a very highly qualified expert in the field of internal medicine and oncology who has a theory that — concerning the causes of cancer and other diseases which may be different from defendant's experts. Nevertheless, I think in this case the jury should be able to hear his opinions and conclusions and decide for themselves. 55 So according to the direction of the Tenth Circuit, which is that this court should vigilantly make detailed findings to fulfill the gatekeeper role, this court is satisfied that the jury may hear the opinions of Dr. Dollinger in this area, as far as we've gone so far, in this area under his speciality of oncology, a subspecialty of internal. 56 Now, if we get into detailed neurology or arthritis, I am going to have to hear from him whether this is covered by his expertise or not. And it may be that some of these opinions may be ruled otherwise. But I think I'm going to have to just take that as it comes up. 57 The Court will permit him to testify. 58 Aplt.App. at 011550-552. Again, we lack specific, detailed findings about Dr. Dollinger's reasoning or the reliability of his methodology in arriving at his conclusions. As with Mr. Miller, the court's findings relative to Dr. Dollinger's credentials and qualifications are simply insufficient by themselves to fulfill the gatekeeper function. As we have emphasized, a district judge asked to admit scientific evidence must determine whether the evidence is genuinely scientific, as distinct from being unscientific speculation offered by a genuine scientist. Mitchell, 165 F.3d at 783 (quoting Rosen, 78 F.3d at 318). These findings simply do not allow us to determine if the district court satisfied that requirement. 59 Similarly, the entirety of the district court's findings regarding Dr. Smith's testimony is as follows: 60 In order to try to satisfy the Tenth Circuit test that they indicate the court must make, the Court will agree with the plaintiffs that by proffer and by testimony a couple years ago, there has been a showing that he is undisputably an expert in the area of toxicology. It's been indicated that his methodology is the same as the methodology that is used in nonlitigation cases. He doesn't have to see patients. He's a Ph.D., not an M.D. He has apparently done research, himself, on heavy metals. He teaches doctors about toxicology, and the plaintiff is conceding that there is no study in risk exposure, if I'm understanding plaintiffs correctly — ... numerical risk exposure. So the Court will overrule the objections, the Daubert objections as to Dr. Smith, and we'll see how it goes. 61 Id. at 012166. Although the court apparently alludes to Dr. Smith's methodology, it made no specific findings and really did nothing more than note an indication that his methodology was the same as that used outside the context of litigation. Id. Even if the court's musings could be considered findings, they do not allow us to determine if the court applied the proper legal standard. As we observed in Dodge I, [g]iven the novelty of the medical causation theory here, such findings are essential. 203 F.3d at 1200 n. 12. 62 Even had the district court performed its gatekeeper function, on this record we would be inclined to conclude that the court abused its discretion by unreasonably limiting the evidence upon which to base the decision. It is plain that a district court exercises significant discretion in deciding how to perform its gatekeeper role. Kumho Tire, 526 U.S. at 158, 119 S.Ct. 1167. While we have held that a Daubert hearing is but one method a court might choose to fulfill its gatekeeper obligation, we have also emphasized that ultimately, the obligation can be satisfied only if the court has sufficient evidence to perform the task. Goebel, 215 F.3d at 1087 (quotation omitted). Therefore, although a district court has discretion to limit the information upon which it will decide the Daubert issue, we review the exercise of that discretion for its abuse. See, e.g., United States v. Nichols, 169 F.3d 1255, 1262-63 (10th Cir.1999); United States v. Call, 129 F.3d 1402, 1405 (10th Cir.1997). 63 The important issue here is the aggregate effect of several of the district court's decisions. Initially, the court limited the length of any Daubert brief and appendix to 20 pages. Aplt.App. at 009857-858. Though the court was put on notice of specific challenges to certain experts' methodology and reasoning, it insisted on the exclusive use of argument and proffers at the Daubert hearing instead of meaningful live witness testimony. Id. at 010166. Although a detailed, in-depth hearing addressing disputed reasoning and methodologies was critical to a proper resolution of the entire case, the Daubert hearing lasted just over four hours and allowed for little more than a cursory review of the contested issues. The court itself proved this point by asking questions of counsel that only the expert could realistically answer. See, e.g., id. at 010775, 010793-796, 010801-802, 010804. 64 After noting the need to hear from the experts in person to decide difficult issues, the court reserved ruling on admissibility until trial. Id. at 010839-840. And, although the court recognized the existence of significant reasoning and methodology problems, id. at 010817-818, it again declined to accept proffers of the experts' reports and full copies of all relevant studies upon which the experts relied. Id. at 010841-842. Finally, during the in camera voir dire of each expert at trial, which was the only time the court heard directly from the experts themselves, the court appeared to place a greater emphasis on keeping the voir dire brief than on a review of reasoning and methodology. See, e.g., id. at 011538-540, 011546, 012015, 012028, 012033, 012159. 65 Although each of the court's decisions taken by itself might well be within its discretion, taken together, these decisions placed an unreasonable limitation on the information available to the court and in our view exceeded the bounds of permissible choice in the circumstances. In a case like this one, where the expert testimony is crucial to the ultimate outcome, is vigorously challenged, and has several obvious areas of concern, we think it unreasonable to limit so severely both the underlying documentation and the use of live witness testimony upon which the court might base a decision. This was not a case where the parties agreed that the Daubert issues could be decided on a stipulated record, nor was it an ordinary case[] where the reliability of an expert's methods [could] properly [be] taken for granted. Kumho Tire, 526 U.S. at 152, 119 S.Ct. 1167. On the contrary, in this case, we fail to see how the Daubert issues could be reliably decided without a meaningful hearing, which of necessity depends upon the use of live witness testimony as opposed to attorneys' arguments. Because we have concluded that the district court did not perform its gatekeeper role, we do not have before us the findings required to determine definitely if the court abused its discretion by so limiting the evidence. However, from the record we do have before us, taken as a whole, we would be inclined to conclude that the court did abuse its discretion. 66 Having concluded that the district court improperly admitted the expert testimony by failing to perform its gatekeeper obligation, we now turn to the appropriate remedy. Given the vast investment of resources in this case by both parties and by the federal judiciary, we are reluctant to render a decision that will further delay a final resolution. Nonetheless, we must be faithful to our precedents which dictate that we reverse and remand to the district court for a new trial. See, e.g., Goebel, 215 F.3d at 1089; Velarde, 214 F.3d at 1211, 1213. In this case, we are simply unable to conclude that the erroneous admission of this expert testimony was harmless. As we stated in Goebel, [e]rroneous admission of evidence is harmless only if other competent evidence is `sufficiently strong' to permit the conclusion that the improper evidence had no effect on the decision. 215 F.3d at 1089 (quoting Lillie v. United States, 953 F.2d 1188, 1192 (10th Cir. 1992)). Here, the testimony of these experts was nothing short of essential to each of the plaintiffs' claims. See, e.g., Aplt.App. at 016094 (elements of negligence claim); id. at 016104 (elements of medical monitoring claim); id. at 016099 (elements of trespass claim). 67 We decline to entertain the possibility of a remand to the district court to make specific findings relative to these experts, for we think no district court would be well positioned to make valid findings given the overwhelming temptation to engage in post hoc rationalization of admitting the experts. We are further persuaded on this issue by the following reasoning of one of our sister circuits: 68 To remand for an evidentiary hearing post-jury verdict undermines Daubert's requirement that some reliability determination must be made by the trial court before the jury is permitted to hear the evidence. Otherwise, instead of fulfilling its mandatory role as a gatekeeper, the district court clouds its duty to ensure that only reliable evidence is presented with impunity. A post-verdict analysis does not protect the purity of the trial, but instead creates an undue risk of post-hoc rationalization. This is hardly the gatekeeping role the Court envisioned in Daubert and its progeny. 69 Mukhtar v. Cal. State Univ., 319 F.3d 1073, 1074 (9th Cir.2003), amending 299 F.3d 1053, 1066 (9th Cir.2002). Accordingly, on the basis of our holdings in Goebel and Velarde, we reverse and remand Dodge II for a new trial.