HomeSkepticism

November, 2002

I. Introduction

In continuation of Renata Zilch's article on the Toxic Mold scare, this is a brief overview of the US court system's treatment of scientific and other expert testimony under the standards set forth by the Supreme Court in Daubert (Daubert v. Merrill Dow Pharmaceuticals, Inc., 509 U.S. 579, 595 (1993)). The "toxic" mold case cited by Renata Zilch in her article had the testimony of the Plaintiff's expert excluded on the grounds that the methodology used was simply too unreliable to be useful to the jury. See Allison v. Fire Insurance Exchange, 98 S.W.3d 227 (Tex. App.-Austin 2002, n.w.h.).

The Texas standard, as discussed below, is based directly on the standards set forth by the U.S. Supreme Court in Daubert. This article is only a brief summary of some of the issues involved in expert testimony and the efforts by the court system in the U.S. to exclude unreliable expert testimony, or "junk science," from trials without interfering with the jury's basic function as a finder of fact.

II. Overview

The U.S. court system places a great amount of faith in the collective ability of a jury to determine issues on a bewildering array of subjects, with no special training or education. That faith is tested somewhat when the jury is faced with testimony from purported experts using techniques or methods of analysis that lie far outside a lay person's normal sphere of knowledge.

The courts have an inherent reluctance to take any issue of fact away from the jury. The credibility of any witness - even an expert witness - is a pure question of fact; there is no legal instruction regarding what a juror may or may not find "credible" or convincing. The court's authority is limited to issues of law, and it has no say on the decision regarding what type of evidence or witness should be believed.

However, the courts - and the drafters of the Federal Rules of Evidence - recognized that unreliable or irrelevant testimony from an expert is not useful to the jury, and in fact ultimately risks confusing them. There exists also the very real concern that a jury will give too much credence to a supposed "expert" based on his qualifications alone, and would be unable to effectively evaluate the science behind any opinions being offered. Finally, there is also the pragmatic fact that many litigants will simply use "hired guns" - terminology from the old west used as shorthand for experts-for-pay - who will essentially testify to anything, as long as they are paid enough.

The Federal Rules therefore set the courts up as "gatekeepers" to insure that only opinions that are backed by a consistent methodology be allowed before the jury. A subjective opinion from an expert with insufficient objective evidence to back it up is essentially no evidence at all.

The courts, however, recognize that their job as gatekeepers is extremely limited in scope. The court does not attempt to weed out an opinion that it believes is incorrect, but only looks to the methodology used to determine whether the result (whatever it may be) was arrived at in a reliable fashion. The exclusion of an expert's testimony is supposed to be the exception, not the rule: "Vigorous 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."

III. Daubert and The Federal Rules of Civil Procedure

Because of the above considerations, the courts have long filled the role of "gate keeper" to ensure that expert testimony reaching the jury meets a basic level of reliability. Older case law (based on the common law "Frye Test") (2) used a fairly stringent standard for determining if an expert could testify in front of a jury: the testimony was inadmissible unless "the principle it is based on is sufficiently established to have a general acceptance to the field in which it belongs." (3)

The Frye test was used by the majority of U.S. Federal courts for over seventy (70) years.(4) While it was widely accepted, a relatively small number of courts either refused to follow the strict test or actually repudiated it directly. (5)

The test, poor at separating any new or novel scientific or technological procedure, came under increasing attack in the Eighties and early Nineties.(6) The Supreme Court in the Daubert finally declared that the more flexible Federal Rules of Evidence had completely replaced the Frye test in determining whether an expert's testimony was admissible. (7)

IV. The Daubert Test for Reliability

Rule 702 of the Federal Rules of Evidence states, in part:

1. 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. (8)

A. The Daubert Factors

The U.S. Supreme Court set out several specific factors that should be used by the courts in evaluating any proposed expert testimony. These factors are not exclusive and some or all may not apply in any given case, but they are always the place to start the reliability analysis. (11) The factors are as follows:

1. Whether the theory or technique has been scientifically tested;
2. Whether the theory or technique has been subject to peer review or publication;
3. The (expected) error rate of the technique used;
4. Acceptance of the theory or technique in the relevant scientific community.(12)

B. "Other" Factors

Since the Daubert decision was handed down, the federal courts have identified a number additional factors which have been useful in examining the reliability of expert opinion. These include the following:

1. Whether experts are proposing to testify about matters growing naturally and directly out of research they have conducted independent of the litigation, or whether they have developed their opinions expressly for purposes of testifying. (15)
2. Whether the expert has unjustifiably extrapolated from an accepted premise to an unfounded conclusion. (16)
3. Whether the expert has adequately accounted for obvious alternative explanations. (17)
4. Whether the field of expertise claimed by the expert is known to reach reliable results for the type of opinion the expert would give (Skeptics will be happy to note that even the most "reliable" astrologer using methodology "widely accepted" by the relevant "scientific" community can be excluded under this analysis). (18)

C. Texas Factors

As Renata's associated article shows, the Texas courts use a test derived directly from the Supreme Court's Daubert analysis.(19) Many states have adopted similar language and analysis, as their state rules of evidence are patterned directly after - if not identical to - the Federal Rules of Evidence. (20)

The Texas Supreme Court, while accepting the analysis and conclusions of the U.S. Supreme Court in Daubert, declined to simply adopt the Daubert factors.(21) The Texas courts therefore use a slightly different formulation of the same concepts. In any case involving a challenge to the reliability of expert testimony, the courts examine the following factors:

1. The extent to which the theory has been or can be tested;
2. The extent to which the technique relies upon a subjective interpretation by the expert;
3. Whether the theory has been subject to publication and/or peer review;
4. The technique's potential rate of error;
5. Whether the underlying theory or technique has been generally accepted as valid by the relevant scientific community; and
6. The non-judicial uses that have been made of the theory or technique (i.e., was is developed simply for litigation?). (22)

Also like Daubert, the courts are cautioned to "focus solely on the validity of principles and methodology underlying the testimony, not the conclusions generated." (24) This is a test designed to find bad methodology, not exclude opinions that the court believes are incorrect.

V. Application to Mold Cases

Issues of causation in "toxic" mold cases, such as the one cited by Renata, are well suited for the above type of reliability analysis. In any case of alleged negligence, it is necessary for a plaintiff to prove not only that the Defendant has breached a duty of care, but that the breach actually caused the damages complained of. This type of causation evidence is outside the general knowledge of a lay person and is therefore almost exclusively within the realm of expert testimony.

Causation, in mold cases (or any case involving alleged health problems from exposure to a substance or chemical), is a two-step hurdle for the plaintiff. First, he or she must show that the substance in question can cause the type of damages attributed to it. This is called "general" causation - can the substance cause the type of damages alleged in the general population? (25)

If the plaintiff passes the first hurdle, then he or she must also show (by a preponderance of the evidence) that the substance in question actually caused his or her specific injuries. (26)

An expert must show a sufficient factual grounding for both of these levels of causation before that testimony can be considered reliable enough to be put in front of a jury. In the Allison case cited by Renata, the plaintiff's expert relied on epidemiological studies, but failed to show that such reliance met accepted standards within the scientific community.(27) In fact, the expert testified that:

1. he could not give a confidence interval for the results of his study;
2. he could not give a calculation for any risk factors for exposure; and
3. he could not state that the techniques used in the study were generally accepted. (28)

This case helps illustrate that the science behind at least some of the mold cases is built more upon wishful thinking and the profit motive than actual science. Until and unless the plaintiffs in such cases can come up with a methodology that passes muster, the "coming wave" of toxic tort litigation risks going the way of bathtub fusion.