Appeal from the United States District Court for the Northern District of Georgia. (No. 1:92-CV-2137-ODE). Orinda D. Evans, Judge.
Before Birch and Barkett, Circuit Judges, and Smith,*fn* Senior Circuit Judge.
Robert Joiner ("Joiner") and his wife, Karen Joiner, brought this suit in state court on August 5, 1993, seeking damages for personal injuries from lung cancer allegedly caused by Robert Joiner's exposure to polychlorinated biphenyls ("PCBs") while working for the City of Thomasville, Georgia ("City"). Monsanto, General Electric Company, and Westinghouse Electric Corporation ("defendants") removed the action to federal district court, which excluded the testimony of the Joiners' experts and granted the defendants' motion for summary judgment, which the Joiners now appeal. Because we find that the district court improperly assessed the admissibility of the proffered scientific expert testimony and overlooked evidence establishing disputed issues of fact, we reverse the summary judgment.
Beginning in 1973, Joiner worked as an electrician in the City's Water & Light Department, a position requiring him to work with and around the City's electrical transformers. Throughout Joiner's employment, all of the City's transformers should have used as a coolant a mineral oil-based dielectric fluid which was free of PCBs.*fn1 However, in 1983, the City discovered PCB contamination in the dielectric fluid used in some of its transformers. From 1983 to 1993, the City conducted tests and concluded that almost one out of every five of the transformers tested presented a PCB hazard.
When a transformer was in need of repair, it was Joiner's duty to open it, drain out the dielectric fluid, bake the core of the transformer dry of dielectric fluid,*fn2 make repairs, refill the transformer with fresh mineral oil dielectric fluid, and then test the transformer. These repairs required that Joiner stick his hands and arms into the dielectric fluid. Joiner testified that dielectric fluid got all over him at times, that he would swallow a small amount of dielectric fluid when it splashed into his mouth, and that dielectric fluid had splashed into his eyes on several occasions.
In 1991, at the age of 37, Joiner was diagnosed with lung cancer. The Joiners' theory of the case was that while Joiner's history of cigarette smoking and his family history of lung cancer may have predisposed him to developing lung cancer,*fn3 his exposure to PCBs and their derivatives--polychlorinated dibenzofurans ("furans") and polychlorinated dibenzodioxins ("dioxins")--served to "promote" his small cell lung cancer.*fn4
Defendants moved for summary judgment on the grounds that (1) there was no admissible scientific evidence that PCBs promoted Joiner's cancer, and (2) there was no evidence that Joiner suffered significant exposure to PCBs, furans, or dioxins. The Joiners responded with the depositions and affidavits of experts who testified that PCBs alone can promote cancer and that furans and dioxins can also promote cancer, that Joiner was exposed to PCBs, furans, and dioxins, and that, in these experts' opinions, such exposure was responsible for Joiner's cancer. The district court deemed inadmissible all of the testimony presented by the Joiners' experts and granted summary judgment for the defendants.*fn5 In addition, although it found Joiner was exposed to PCBs, the court asserted that there was no credible evidence that Joiner had been exposed to furans and dioxins, and granted summary judgment against the Joiners on the question of exposure to furans and dioxins. Joiner v. General Elec. Co., 864 F. Supp. 1310, 1326 (N.D.Ga. 1994).
On appeal, the Joiners reassert the admissibility of their expert testimony to establish causation. They also contest the district court's grant of summary judgment on the issue of Joiner's exposure to furans and dioxins.
We review a grant of summary judgment de novo. Fane v. Edenfield, 945 F.2d 1514, 1516 (11th Cir. 1991), aff'd, 507 U.S. 761, 113 S. Ct. 1792, 123 L. Ed. 2d 543 (1993). Summary judgment is appropriate when there is no genuine issue of material fact, and the moving party is entitled to judgment as a matter of law. Fed.R.Civ.P. 56(c). The moving party bears the burden of showing that there is no issue of material fact. Celotex Corp. v. Catrett, 477 U.S. 317, 325, 106 S. Ct. 2548, 2553-54, 91 L. Ed. 2d 265 (1986).
A district court's ruling on the admissibility of evidence is reviewed for abuse of discretion. Ad-Vantage Tel. Directory Consultants, Inc. v. GTE Directories Corp., 37 F.3d 1460, 1463 (11th Cir. 1994). Because the Federal Rules of Evidence governing expert testimony display a preference for admissibility, we apply a particularly stringent standard of review to the trial judge's exclusion of expert testimony. See, e.g., Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579, 113 S. Ct. 2786, 2794, 125 L. Ed. 2d 469 (1993); In re Paoli R.R. Yard PCB Litigation, 35 F.3d 717, 750 (3d Cir. 1994). To the extent that the district court's ruling turns on an interpretation of a Federal Rule of Evidence, our review is plenary. Id. at 749.
B. The Admissibility of Expert Testimony
In 1923, Frye v. United States established a "general acceptance" test that guided district courts in determining when to admit scientific evidence. Frye, 54 App. D.C. 46, 293 F. 1013, 1014 (D.C.Cir. 1923). This test required courts to exclude any novel scientific evidence not already grounded in a principle that had attained "general acceptance in the particular field" in which it belonged. Id.
In 1975, the Federal Rules of Evidence ("Rules") introduced a more liberal approach to the question of the admissibility of scientific evidence.*fn6 Rule 702, which specifically governs expert testimony, provides:
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.
Fed.R.Evid. 702. Notwithstanding the Rules, most courts continued to adhere to the "general acceptance" test.
In 1993, the Supreme Court in Daubert, U.S. at, 113 S. Ct. at 2793, specifically held that the Rules superseded the Frye "general acceptance" test. The Court made clear that the critical concerns of Rule 702 are evidentiary reliability and relevancy. Daubert, U.S. at, 113 S. Ct. at 2795. Thus, an expert's bald statement that he or she is imparting "scientific knowledge" does not automatically render that expert's opinion admissible. In order to best ensure relevant and reliable testimony and exclude "unsupported speculation," Daubert establishes a two-pronged test which requires a district court, before it may admit scientific testimony, to determine "whether the expert is proposing to testify to (1) scientific knowledge that (2) will assist the trier of fact to understand or determine a fact in issue." Id. at, 113 S. Ct. at 2796. This "gatekeeping" role calls for the trial judge to make a "preliminary assessment of whether the reasoning or methodology underlying the testimony is scientifically valid, i.e., whether it is reliable; and whether that reasoning or methodology properly can be applied to the facts in issue," i.e., whether it is relevant to the issue involved. Id. Proffered scientific evidence must satisfy both prongs to be admissible.
Under the first prong, evidentiary reliability, the district court must examine the reasoning or methodology underlying the expert opinion to determine whether it utilizes valid scientific methods and procedures. Trial judges must evaluate scientific processes and studies with which they may not be intimately familiar, but be careful not to cross the line between deciding whether the expert's testimony is based on "scientifically valid principles" and deciding upon the correctness of the expert's conclusions. The latter inquiry is for the jury and, therefore, judges may not implicitly factor it into their assessment of reliability.
Daubert suggests several factors to aid federal judges in evaluating whether a particular scientific theory or study is reliable: (1) its empirical testability; (2) whether the theory or study has been published or subjected to peer review; (3) whether the known or potential rate of error is acceptable; and (4) whether the method is generally accepted in the scientific community. Id. at, 113 S. Ct. at 2797-98. These factors are neither exhaustive nor applicable in every case. See also Paoli, 35 F.3d at 742. Where appropriate, they serve as indicia of the reliability of the basis of an expert's testimony.
Under the second prong, relevance, the district court must determine whether the methodology or reasoning underlying the expert opinion relates to the issue at hand, i.e., whether it assists the trier of fact in understanding the evidence or a fact in issue. Daubert, U.S. at, 113 S. Ct. at 2795. In this regard, the Daubert Court discusses the concept of "fitness," that is, "whether expert testimony proffered in the case is sufficiently tied to the facts of the case that it will aid the jury in resolving a factual dispute." Id. at, 113 S. Ct. at 2795-96 (quoting United States v. Downing, 753 F.2d 1224, 1242 (3d Cir. 1985)).
In analyzing the admissibility of expert testimony, it is important for trial courts to keep in mind the separate functions of judge and jury, and the intent of Daubert to loosen the strictures of Frye and make it easier to present legitimate conflicting views of experts for the jury's consideration. Frye required that before an expert could testify, the proffered opinion had to be generally accepted in the pertinent field. The necessity for such broad acceptance as a condition for admissibility was eliminated by Rule 702. The admission of scientific evidence that might not yet be generally accepted in the field, however, is contingent on a trial court's finding that such evidence is indeed scientifically legitimate, and not "junk science" or mere speculation. This gatekeeping role is simply to guard the jury from considering as proof pure speculation presented in the guise of legitimate scientifically-based expert opinion. It is not intended to turn judges into jurors or surrogate scientists. Thus, the gatekeeping responsibility of the trial courts is not to weigh or choose between conflicting scientific opinions, or to analyze and study the science in question in order to reach its own scientific ...