What is an environmental expert? The impact of Daubert, Joiner and Kumho Tire on the admissibility of scientific expert evidence.

• Author: Gagen, Andrew B.

I.

INTRODUCTION

Environmental experts are typically environmental engineers and environmental and occupational health doctors (1) whose testimony is based on "scientific, technical, or other specialized knowledge" that "will assist the trier of fact." (2) In complex environmental and toxic tort (3) cases, "scientific, technical or other specialized" expert evidence (4) "has become virtually indispensable, especially on the issues of causation (5) and damages." (6) For the following reasons, environmental and toxic tort expert evidence must be treated differently than ordinary evidence in environmental and toxic tort litigation.

First, unlike expert evidence, ordinary evidence is typically derived from fact witnesses whose testimony is limited to inferences and opinions based on firsthand knowledge. (7) An expert witness' testimony, in contrast, is not limited to firsthand knowledge or observation. (8) Scientific expert witnesses may testify to inferences and opinions based on data (tests, models, and peer publications) "reasonably relied upon by experts in the particular field." (9) A distinction is recognized between lay and expert witnesses because experts possess an "unique ability" to draw conclusions from data. (10) The United States Court of Appeals for the District of Columbia first recognized this distinction in Frye v. United States. (11) Congress codified this distinction in the adoption of Article VII of the Federal Rules of Evidence ("Rules") in 1975, (12) which separates Rule 701 (13) from Rules 702 (14) and 703, (15) in order to distinguish ordinary witnesses from expert witnesses. Since the enactment of the Rules, the Supreme Court has twice recognized that Rules 702 and 703 grant expert witnesses "wide latitude to offer opinions ... not based on firsthand knowledge or observation." (16) Because expert witnesses are not limited to firsthand knowledge, their testimony ought to be treated differently than more reliable firsthand evidence from lay witnesses.

Second, expert evidence in environmental and toxic tort cases often "involve[s] complex scientific theories that are novel, and affect many people beyond just the individual litigants." (17) Novel scientific expert evidence is evidence that has not received widespread peer review (18) and/or acceptance from the judicial or scientific communities. (19) Such evidence raises countervailing concerns. On the one hand, a "liberal admission standard [may] impede the judicial process" (20) by allowing "junk science" (21) into the courtroom. On the other hand, "a restrictive standard will prevent courts from becoming fully informed about [novel] scientific developments," (22) which may be relied upon by toxic tort and environmental litigants. As technology and the underlying scientific theories continue to grow, more litigation will include complex and/or novel scientific expert evidence. (23) Given the possible increased reliance on novel scientific evidence and the potential impacts of such litigation beyond just the individual litigants, (24) scientific expert evidence ought to be treated differently than ordinary witness testimony.

The third reason for treating scientific expert evidence differently than lay witness evidence in environmental and toxic tort litigation is the latency period of the diseases involved in such litigation. (25) A disease may develop many years after an acute exposure or after many years of long-term, low-dose exposure to a carcinogen or toxin. (26) The long latency period obscures the chain of causation. The causation chain is further obscured in novel cases because the mechanism by which the toxin causes the disease may not be understood. (27) Subsequently, a fact witness, or a witness with firsthand knowledge, does not typically possess the experience or knowledge to explain the causal link to the trier of fact. (28) Given the technical and complex nature of proving causation in a typical toxic tort claim, (29) scientific expert evidence is needed to establish a prima facie case. (30)

Finally, the difference perceived by a jury between scientific expert evidence and ordinary evidence can be so great that a court must treat expert evidence differently. A jury may presuppose that the scientific expert evidence it confronts is infallible, (31) because technology, such as automobiles and computers, surrounds our daily lives. (32) Therefore, scientific expert evidence should be treated differently than ordinary evidence because scientific expert evidence may enter a courtroom with a preconceived notion of infallibility that may misguide a jury. For these reasons, scientific expert evidence should continue to be treated differently than non-expert evidence, particularly in environmental and toxic tort litigation.

Part II of this Note discusses the evolution of expert evidence from Frye v. United States, (33) Daubert v. Merrell Dow Pharmaceuticals, Inc., (34) and General Electric Co. v. Joiner (35) to the Supreme Court's most recent interpretation of Rule 702 in Kumho Tire Co. v. Carmichael. (36) Part III discusses the impact that Kumho Tire will have on the admissibility of scientific expert evidence. Specifically, this section argues that the discretionary application of the Daubert and non-Daubert factors to expert evidence will open the evidentiary gates wider for the admission of scientific expert evidence, which will tilt the potential admission of scientific expert evidence back toward an equilibrium between plaintiffs and defendants. Additionally, this section discusses the consequences of a trial court's failure to consider a relevant Daubert or non-Daubert factor. Part IV first discusses that extensive evidentiary hearings may be the most effective way to determine the admissibility of novel expert evidence, and then argues that the model approach to admit novel scientific expert evidence in light of Daubert and Kumho Tire is for the litigant to develop a detailed record during discovery in addition to a Rule 26 Report of the expert's opinion, (37) and to present the experts' individual proffered expert evidence as a whole conclusion during a Daubert inquiry. This section concludes that Trial judges should assign limited weight to the "general acceptance" factor when evaluating novel expert evidence during a Daubert inquiry.

II.

THE EVOLUTION OF EXPERT EVIDENCE: FRYE, DAUBERT, JOINER, AND KUMHO TIRE

In Frye v. United States, the United States Court of Appeals for the District of Columbia promulgated a test for the admissibility of scientific expert evidence. (38) The appellate court held that expert testimony "must be sufficiently established to have gained `general acceptance' in the particular field in which it belongs." (39) The Frye court noted that "just when the scientific principle or discovery crosses the line between the experimental and demonstrable states is difficult to define." (40) The "general acceptance" test failed to define this line, and proved to be too conservative for the judicial system. (41) Moreover, the "general acceptance" test misconceived the scientific process, because the validity of the test is premised on the belief that acceptance equals scientific validity. However, the degree of peer-acceptance is not a substantive test of scientific validity. (42)

1. DAUBERT V. MERRELL Dow PHARMACEUTICALS, INC.

   Seventy years later, a unanimous Supreme Court rejected the "general acceptance" test as the sole criteria for determining the admissibility of scientific expert evidence in Daubert v. Merrell Dow Pharmaceuticals, Inc., (43) and supplanted it with the relevance and reliability standards of the Federal Rules of Evidence. (44) The "general acceptance" test was demoted to one of several factors to be considered in determining the admissibility of scientific expert evidence. (45)

   In Daubert, two families claimed that Bendectin, an anti-nausea medication administered to pregnant women, caused birth defects in their children. (46) The district court granted summary judgment in favor of the defendant, (47) and the Ninth Circuit affirmed on grounds that the proffered theories of the two families' expert witnesses were not generally accepted in the scientific community. (48) The U.S. Supreme Court vacated and remanded the Ninth Circuit's ruling, because the lower decisions relied "almost exclusively on [the] `general acceptance'" test. (49)

   In Daubert, the Supreme Court focused on the plain language of Rule 702, and promulgated a two-prong test to assist trial judges (50) in determining the admissibility of expert evidence. (51) The test establishes the trial judge's role as gatekeeper, requiring trial judges to determine, pursuant to Rule 104(a), (52) whether the proffered expert evidence is "(1) scientific knowledge that (2) will assist the trier of fact to understand or determine the facts in issue." (53) This gatekeeper role requires the trial judge to make a "preliminary assessment of whether the reasoning or methodology underlying the testimony is scientifically valid" under the first prong, and "whether that reasoning or methodology can be applied properly to the facts in issue" under the second prong. (54)

   In other words, the first prong addresses the reliability of the proffered expert evidence, requiring the trial judge to determine whether the expert evidence has been subjected to the scientific method, and is not merely subjective or "unsupported speculation." (55) The second prong addresses the relevance of the proffered expert evidence, requiring the trial judge to determine whether the expert testimony "fits" the issue to which the expert is testifying. (56) The proffered expert evidence must satisfy both prongs to be admissible. (57)

   Daubert offered four discretionary factors to assist the trial judge's determination of whether the proffered expert evidence is sufficiently reliable to be considered by the trier of fact. This non-exhaustive list of factors includes...