Opinion ID: 779092
Heading Depth: 3
Heading Rank: 2

Heading: District Court's Role Under Daubert

Text: 31 Rule 702 of the Federal Rules of Evidence, which governs the admissibility of expert and other scientific or technical expert testimony, provides as follows: 32 If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise, if (1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case. 33 Fed.R.Evid. 702. 34 Interpreting Rule 702 in Daubert, the Supreme Court rejected the traditional Frye rule, under which courts required that a scientific theory be generally accepted by the scientific community in order to be admissible. Daubert, 509 U.S. at 585-89, 113 S.Ct. 2786; see Frye v. United States, 293 F. 1013, 1014 (D.C.Cir.1923); see also Zuchowicz v. United States, 140 F.3d 381, 386 n. 5 (2d Cir.1998) (discussing Supreme Court's rejection of Frye ). Concluding that the bright-line general acceptance test established in Frye was at odds with the liberal thrust of the Federal Rules of Evidence, Daubert, 509 U.S. at 588, 113 S.Ct. 2786 (internal quotation marks omitted), the Supreme Court has made clear that the district court has a gatekeeping function under Rule 702 — it is charged with the task of ensuring that an expert's testimony both rests on a reliable foundation and is relevant to the task at hand. Id. at 597, 113 S.Ct. 2786; accord Campbell, 239 F.3d at 184; Federal Judicial Center, Reference Manual on Scientific Evidence 11 (2d ed.2000). 35 In fulfilling this gatekeeping role, the trial court should look to the standards of Rule 401 in analyzing whether proffered expert testimony is relevant, i.e., whether it `ha[s] 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.' Campbell, 239 F.3d at 184 (quoting Fed.R.Evid. 401) (alteration in original). Next, the district court must determine whether the proffered testimony has a sufficiently `reliable foundation' to permit it to be considered. Id. (quoting Daubert, 509 U.S. at 597, 113 S.Ct. 2786). In this inquiry, the district court should consider the indicia of reliability identified in Rule 702, namely, (1) that the testimony is grounded on sufficient facts or data; (2) that the testimony is the product of reliable principles and methods; and (3) that the witness has applied the principles and methods reliably to the facts of the case. Fed.R.Evid. 702. In short, the district court must 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. 36 Although Rule 702 sets forth specific criteria for the district court's consideration, the Daubert inquiry is fluid and will necessarily vary from case to case. The Supreme Court has identified a number of factors bearing on reliability that district courts may consider, such as (1) whether a theory or technique can be (and has been) tested, Daubert, 509 U.S. at 593, 113 S.Ct. 2786; (2) whether the theory or technique has been subjected to peer review and publication, id.; (3) a technique's known or potential rate of error, and the existence and maintenance of standards controlling the technique's operation, id. at 594, 113 S.Ct. 2786; and (4) whether a particular technique or theory has gained general acceptance in the relevant scientific community, id. See also Fed. Deposit Ins. Corp. v. Suna Assocs., Inc., 80 F.3d 681, 687 (2d Cir.1996) (discussing Daubert factors); Jack B. Weinstein & Margaret A. Berger, Weinstein's Federal Evidence § 702.05[2][a], at 702-66 to 702-72.2 (Joseph M. McLaughlin ed., 2d ed.2002) (listing factors for the district court's consideration identified in Daubert and its progeny). These factors do not constitute, however, a definitive checklist or test. Daubert, 509 U.S. at 593, 113 S.Ct. 2786. Rather, [t]he inquiry envisioned by Rule 702 is ... a flexible one, id. at 594, 113 S.Ct. 2786, and the gatekeeping inquiry must be tied to the facts of a particular case, Kumho Tire, 526 U.S. at 150, 119 S.Ct. 1167 (internal quotation marks omitted). 37 In undertaking this flexible inquiry, the district court must focus on the principles and methodology employed by the expert, without regard to the conclusions the expert has reached or the district court's belief as to the correctness of those conclusions. See Daubert, 509 U.S. at 595, 113 S.Ct. 2786. But, as the Supreme Court recognized in Joiner, 38 conclusions and methodology are not entirely distinct from one another.... [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. A court may conclude that there is simply too great an analytical gap between the data and the opinion proffered. 39 522 U.S. at 146, 118 S.Ct. 512. Thus, when an expert opinion is based on data, a methodology, or studies that are simply inadequate to support the conclusions reached, Daubert and Rule 702 mandate the exclusion of that unreliable opinion testimony. See Heller v. Shaw Indus., Inc., 167 F.3d 146, 153 (3d Cir.1999) ([A] district court must examine the expert's conclusions in order to determine whether they could reliably follow from the facts known to the expert and the methodology used.). 40 This is not to suggest that an expert must back his or her opinion with published studies that unequivocally support his or her conclusions. See Bonner v. ISP Techs., Inc., 259 F.3d 924, 929 (8th Cir.2001) (observing that [t]here is no requirement `that a medical expert must always cite published studies on general causation in order to reliably conclude that a particular object caused a particular illness') (quoting Heller, 167 F.3d at 155); see also Fed. Deposit Ins. Corp., 80 F.3d at 687 (finding no abuse of discretion in the admission of expert testimony based on a hybrid of two widely used methods). In McCullock, for example, we affirmed the district court's admission of medical expert testimony despite the fact that the expert could not point to a single piece of medical literature that specifically supported the expert's opinion. 61 F.3d at 1043. Where an expert otherwise reliably utilizes scientific methods to reach a conclusion, lack of textual support may go to the weight, not the admissibility of the expert's testimony. Id. at 1044; see also Zuchowicz, 140 F.3d at 387. A contrary requirement would effectively resurrect a Frye -like bright-line standard, not by requiring that a methodology be `generally accepted,' but by excluding expert testimony not backed by published (and presumably peer-reviewed) studies. Heller, 167 F.3d at 155. Such a bright-line requirement would be at odds with the liberal admissibility standards of the federal rules and the express teachings of Daubert. See McCullock, 61 F.3d at 1042, 1044. 41 The flexible Daubert inquiry gives the district court the discretion needed to ensure that the courtroom door remains closed to junk science while admitting reliable expert testimony that will assist the trier of fact. To warrant admissibility, however, it is critical that an expert's analysis be reliable at every step. As Chief Judge Becker of the Third Circuit has explained, the Daubert requirement that the expert testify to scientific knowledge — conclusions supported by good grounds for each step in the analysis — means that any step that renders the analysis unreliable under the Daubert factors renders the expert's testimony inadmissible. In re Paoli R.R. Yard PCB Litig., 35 F.3d 717, 745 (3d Cir.1994); see also Heller, 167 F.3d at 155 ([T]he reliability analysis applies to all aspects of an expert's testimony: the methodology, the facts underlying the expert's opinion, the link between the facts and the conclusion, et alia. ). 42 In deciding whether a step in an expert's analysis is unreliable, the district court should undertake a rigorous examination of the facts on which the expert relies, the method by which the expert draws an opinion from those facts, and how the expert applies the facts and methods to the case at hand. A minor flaw in an expert's reasoning or a slight modification of an otherwise reliable method will not render an expert's opinion per se inadmissible. The judge should only exclude the evidence if the flaw is large enough that the expert lacks `good grounds' for his or her conclusions. In re Paoli, 35 F.3d at 746; see Daubert, 509 U.S. at 590, 113 S.Ct. 2786. This limitation on when evidence should be excluded accords with the liberal admissibility standards of the federal rules and recognizes that our adversary system provides the necessary tools for challenging reliable, albeit debatable, expert testimony. As the Supreme Court has explained, [v]igorous cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof are the traditional and appropriate means of attacking shaky but admissible evidence. Daubert, 509 U.S. at 596, 113 S.Ct. 2786; accord Weinstein, § 702.05[3] at 702-76. 43 In addition, if the admissible evidence is insufficient to permit a rational juror to find in favor of the plaintiff, the court remains free to direct a verdict or grant summary judgment for defendant. See Weisgram v. Marley Co., 528 U.S. 440, 455-56, 120 S.Ct. 1011, 145 L.Ed.2d 958 (2000) (affirming appellate grant of judgment as a matter of law where court of appeals concluded that expert testimony was erroneously admitted and found the remaining evidence insufficient to support the jury's verdict); Daubert, 509 U.S. at 596, 113 S.Ct. 2786 (citing Fed.R.Civ.P. 50(a) & 56); see, e.g., Brooks v. Outboard Marine Corp., 234 F.3d 89, 92 (2d Cir. 2000) (per curiam) (affirming district court's grant of summary judgment). We have cautioned, however, that the district court's Daubert gatekeeping role does not permit the district court, in ruling on evidentiary sufficiency, to reject admissible expert testimony. See In re Joint E. & S. Dist. Asbestos Litig., 52 F.3d 1124, 1132-34 (2d Cir.1995); see also Marbled Murrelet, 83 F.3d at 1066-67. Once the district court has deemed the evidence sufficiently reliable so as to be admissible, it is bound to consider the evidence in the light most favorable to plaintiff when deciding motions for summary judgment or judgment as a matter of law. In re Joint, 52 F.3d at 1135.