Opinion ID: 1897734
Heading Depth: 1
Heading Rank: 3

Heading: Expert Testimony on Proof of Causation in Iowa.

Text: Generally, we have been committed to a liberal view on the admissibility of expert testimony. See Leaf v. Goodyear Tire & Rubber Co., 590 N.W.2d 525, 532 (1999) (citing court's history of maintaining liberal view on admissibility). Our broad test for admissibility of expert testimony has two preliminary areas of judicial inquiry that must be considered before admitting expert testimony. See Iowa R. Evid. 5.702. The court must first determine if the testimony will assist the trier of fact in understanding the evidence or to determine a fact in issue. Id. This preliminary determination not only requires the court to consider the existence of a reliable body of scientific, technical, or other specialized knowledge, but it also requires the court to ensure the evidence is relevant in assisting the trier of fact. See Johnson v. Knoxville Cmty. Sch. Dist., 570 N.W.2d 633, 637 (Iowa 1997) (stating that, to be relevant, the evidence must be reliable, and reliability is an implicit requirement of admissibility under Iowa Rule of Evidence 5.702 because unreliable testimony cannot assist the trier of fact); see also Bonner v. ISP Techs., Inc., 259 F.3d 924, 929 (8th Cir.2001) (The rule's concern with `scientific knowledge' is a reliability requirement, while the requirement that the evidence `assist the trier of fact to understand the evidence or determine a fact in issue' is a relevance requirement.) Second, the court must determine if the witness is qualified to testify as an expert by knowledge, skill, experience, training, or education. Iowa R. Evid. 5.702. In assessing the reliability of scientific evidence under the first area of preliminary inquiry, we essentially utilize an ad hoc approach to decide if the scientific area of expertise produces results that are reliable enough to assist the trier of fact. State v. Hall, 297 N.W.2d 80, 85 (Iowa 1980) (rejecting Frye test of general scientific acceptance). When the scientific evidence is particularly novel or complex, however, we have suggested that courts consider the relevant factors identified by the United States Supreme Court in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 593-94, 113 S.Ct. 2786, 2796-97, 125 L.Ed.2d 469, 482-83 (1993). Leaf, 590 N.W.2d at 532. These factors help assess reliability of expert evidence by evaluating the scientific validity of the reasoning and methodology as applied to the facts of the case. Daubert, 509 U.S. at 592-93, 113 S.Ct. at 2796, 125 L.Ed.2d at 482. See also Bonner, 259 F.3d at 929 (recognizing the purpose of Daubert factors). These factors are: (1) whether the theory or technique is scientific knowledge that can and has been tested, (2) whether the theory or technique has been subjected to peer review or publication, (3) the known or potential rate of error, or (4) whether it is generally accepted within the relevant scientific community. Leaf, 590 N.W.2d at 533. The target of the court's scrutiny is on the principles and methodologies used to reach the expert's conclusions, not the conclusions themselves. Daubert, 509 U.S. at 595, 113 S.Ct. at 2797, 125 L.Ed.2d at 484. We emphasize that the ad hoc Hall test remains our general approach to evaluating reliability, but the rapid advancements in science and medicine have presented particularly unique challenges for courts seeking to ensure the integrity of scientific evidence used by juries. This judicial role has become increasingly difficult and complex, yet important, as the access to and availability of sources of information and opinions continue to expand. Thus, we encourage a more expansive judicial gatekeeping function in difficult scientific cases. At the same time, it follows that application of Daubert considerations is not appropriate in cases involving technical[] or other specialized knowledge because such nonscientific evidence is not as complex. Johnson, 570 N.W.2d at 639. As a result, the foundational showing of reliability for nonscientific evidence is correspondingly lower. See id. at 637. For example, we have previously noted the inapplicability of Daubert to general medical issues. Johnson, 570 N.W.2d at 638 (quoting Thornton v. Caterpillar, Inc., 951 F.Supp. 575, 578 (D.S.C.1997)). In all circumstances involving expert testimony, the proponent of the evidence has the burden of demonstrating to the court as a preliminary question of law the witness's qualifications and the reliability of the witness's opinion. Iowa R. Evid. 5.104( a ); see State v. Myers, 382 N.W.2d 91, 93 (Iowa 1986); see also McClain v. Metabolife Int'l, Inc., 401 F.3d 1233, 1238 (11th Cir.2005). Although it is the province of the jury to evaluate the credibility of expert witnesses, trial courts have a well-recognized role as guardians of the integrity of expert evidence offered at trials. See, e.g., 31A Am.Jur.2d Expert and Opinion Evidence § 47, at 73 (2002) (The qualifications of an expert witness must be carefully scrutinized by the court to guard against a pseudolearned person or charlatan who may give erroneous testimony or opinions without a sound foundation. (citing Webb v. Olin Mathieson Chem. Corp., 9 Utah 2d 275, 342 P.2d 1094, 1097 (1959))); Kumho Tire Co. v. Carmichael, 526 U.S. 137, 149, 119 S.Ct. 1167, 1174-75, 143 L.Ed.2d 238, 251 (1999); see also Iowa R. Evid. 5.104( a ) official cmt.; Leaf, 590 N.W.2d at 534 (noting issues of admissibility of expert testimony will be raised prior to trial). Like Daubert, the case before us is a toxic-tort case. The proffered testimony at issue involves complex medical issues, including the potential biological effect of PPA on the human body and on Ranes, a corresponding differential diagnosis, and the alternative diagnosis of a complex neurological disease. Such testimony is certainly complex, and it has the potential to achieve an exaggerated impact on the fact-finding process. Leaf, 590 N.W.2d at 534. The facts presented are far from general, and unlike the cases cited in Johnson, the methodology in this case is not based on practical experience and acquired knowledge, but on a somewhat novel scientific procedure characteristic of scientific knowledge. 570 N.W.2d at 638. Additionally, Daubert itself was a toxic-tort case involving a complex issue of causation. See Daubert, 509 U.S. at 582, 113 S.Ct. at 2791, 125 L.Ed.2d at 476. Thus, the district court's application of relevant Daubert considerations in preliminarily assessing the reliability of Dr. Thoman's methodology was appropriate under Iowa law as an exercise of the court's gatekeeping function. [1]