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An Introduction to the Admissibility of Expert Opinion

June 23, 2011

We have talked repeatedly about July 1, 1975 as the date the Federal Rules were adopted.  So, because of that watershed event, hardly anything that happened before then remains particularly important to the modern practicing trial lawyer who wants to do what trial lawyers do: win cases.  On the other hand, much of what happened before that date remains important to law professors and other academics who don’t have to argue and win evidence struggles in a courtroom.  (There is an interesting passage about this in Daubert.)  Happily, we have an exception with expert testimony; one that will help us to understand what the law currently says about the “foundation” for the admissibility of expert opinion. 

Until 1993 when the United States Supreme Court decided Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579, 585 (1993), no court had definitively explained the role of Rule 702 in the admissibility of expert opinion.  Until then, most courts used as the test for admissibility of expert opinion the rule set forth in Frye v. United States, 293 F. 1013 (D.C. Cir. 1923).  There are two interesting things about the “Frye test” that inform modern trial lawyers on how to introduce expert opinion, and also how to oppose its admission.  First, an analysis of Frye tells us that the central issue regarding the admissibility of expert opinion has not changed since 1923.  While there are three elements to the “foundation” for expert opinion, it often really boils down to the reliability of the underlying principles and methods the expert used in arriving at the opinion (knowledge) to be presented to the jury in the trial.  Second, the way the court expressed its rule is simply awesome!  The Frye rule is called the “general acceptance” test, and though it is no longer applied in trials, it helps us to understand the modern requirement of reliability. 

James Alphonso Frye was charged with murder.  At his trial in the District of Columbia in the early 1920’s, he offered into evidence the testimony of an expert witness who would testify that Frye was telling the truth when he denied guilt.  As it does now in almost every challenge to the admissibility of an expert’s opinion, the admissibility of the opinion came down to reliability.  Let’s look at it as two questions:

  1. How did the expert arrive at this opinion?
  2. Was this method sufficiently reliable that the opinion should be allowed into evidence?

The D.C. Circuit explained all this in compelling terms.  As to the first question, the answer was that the expert used a lie detector test.  The court stated:

In the course of the trial counsel for defendant offered an expert witness to testify to the result of a deception test made upon defendant.  The test is described as the systolic blood pressure deception test.  It is asserted that blood pressure is influenced by change in the emotions of the witness, and that the systolic blood pressure rises are brought about by nervous impulses sent to the sympathetic branch of the autonomic nervous system.  Scientific experiments, it is claimed, have demonstrated that fear, rage, and pain always produce a rise of systolic blood pressure, and that conscious deception or falsehood, concealment of facts, or guilt of crime, accompanied by fear of detection when the person is under examination, raises the systolic blood pressure in a curve, which corresponds exactly to the struggle going on in the subject’s mind, between fear and attempted control of that fear, as the examination touches the vital points in respect of which he is attempting to deceive the examiner.

293 F. at 1013-14. 

The court then focused in on the question we still find most important even today under the Federal Rules of Evidence: the reliability of the method used by the expert.  Discussing the challenge of distinguishing between an acceptable level of reliability and something too speculative, the court stated:

Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define.  Somewhere in this twilight zone the evidential force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs

293 F. at 1014 (quoted as an “infamous passage,” and emphasis added, in Daubert, 509 U.S. at 585-86).

In 1923, as today, the inquiry into the admissibility of expert opinion included reliability: “the thing from which the deduction is made,” meaning the principles and methods the expert used in arriving at the opinion to which he is now proposing to testify, must have been reliable as measured by “general acceptance” in the applicable field of study.  However, the Daubert Court held the “austere standard” of Frye was too “rigid” a test for measuring reliability, and ruled that “the Frye test was superseded by the adoption of Federal Rules of Evidence.”  The Court held, nevertheless, that reliability remained a focus for determining the admissibility of expert opinion.  The Court then applied the requirement of reliability in the context of Rule 702, and left us with three elements for the foundation for the admissibility of expert opinion:

  • The expert must be qualified
  • The opinion must assist the trier of fact
  • The principles and methods [way the expert went about … ] the expert used in reaching the opinion must be reliable

Since then, Rule 702 has been amended to set forth three subelements related to reliability.  Here’s the text of the rule:

Rule 702. Testimony by Experts

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.

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