In 1993, in Daubert v. Merrell Dow Pharmaceuticals, Inc. 509 U.S. 579 (1993), the Supreme Court finally clarified that Rule 702, not Frye, controlled the admission of expert testimony in the federal courts.  The Supreme Court held that when expert evidence based upon “scientific knowledge” is offered at trial, the judge, upon proper motion by a litigant who challenges the admissibility of the testimony, should act as a gatekeeper and first determine whether the proffered evidence is “reliable”–Whether it is evidence that can be trusted to be scientifically valid.  In the outcome of Daubert, a number of courts had to address the unresolved issue whether the Daubert factors by which reliability was to be tested should also be applied to experts offering opinion testimony that was not based on clearly identified scientific principles, but which sprung from “technical or other specialized knowledge.” Since the clear majority of informed opinion seemed to favor applying a Daubert-like standard to all expert opinion testimony, the Advisory Committee on the Rules of Evidence endorsed that requirement by amending Federal Rule of Evidence 702 in 2000. 

The amended version includes:

(1) The testimony is sufficiently based upon reliable 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.

This means that if the 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 sufficiently based upon reliable 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. 

I. The 2000 Amendment of Rule 702

The Supreme Court clarified its Daubert opinion in the case of Kumho Tire Co. V.Carmichael, 119 S.Ct. 1167 (1999) after the proposed first amendment by mandating that the trial judges’ duty to act as gatekeepers, charged with insuring that only reliable expert opinion evidence be admitted, apply to all forms of expert testimony.  The Court thus approved the above proposed amendment, which had already been widely revealed and publicized prior to the Court’s decision in Kumho Tire.   

Moreover, even after the Amendment of Rule 702, the framers emphasized again the non-exclusive use of Rule 702 in judging whether proffered scientific expert opinion testimony meets the Daubert criteria of reliability:

The specific factors demonstrated by the Daubert Court are:

(1)    whether the expert’s theory or technique can be challenged in some objective or in  a subjective sense, conclusory approach that cannot reasonably be assessed for reliability;

(2)    whether the technique or theory has been subject to peer review and publication:

(3)    The known or potential rate of error of the technique or theory when applied;

(4)    The existence and maintenance of standards and controls; and

(5)    Whether the technique or theory has been generally accepted in the scientific community.

In Kumho Tire, the Court recognized that these same factors might not be applicable to all forms of expert opinion testimony, and stressed that these factors constituted not mandates but flexible guidelines.  The courts could look at other factors depending on the particular circumstances of a case, were likely to permit an assessment of the reliability of the nonscientific expert opinion testimony offered to the tribunal. The Court also specifically declared that the gatekeeping function of trial judges “applies not only to testimony based on ‘scientific’ knowledge, but also to knowledge based on ‘technical’ and ‘other specialized’ knowledge.”

The Daubert Court in 1993 explicitly stated that trial judge’s focus must be towards examining the “principles and methodology, not on the conclusions they generate”.  Later on in General Electric v. Joiner, 522 U.S. 136 (1997) the Court changed its opinion from this announced position and recognized that “conclusions and methodology are correlated and not entirely distinct from one another.” The language of the proposed amendment to Rule 702 covers both methodology as well as the conclusion, in that it directs a trial court to determine not only whether the methods used by an expert and the principles upon her analysis rests have been determined to be reliable, but also whether “the witness has applied the principles and methods reliably” to the facts that are in controversy in the particular case.

Moreover, although Daubert remains the standard by which admissibility in federal cases is measured under Federal Rule of Evidence 702, states remain free to apply other evidentiary standards.  The reason for this is that state courts receive 200 times more criminal prosecutions than federal courts, because forensic science is used most commonly in crimes of violence, and most crimes of violence are tried in state courts. 

II. Rule 703. Bases of Opinion Testimony By Experts

Another amendment to the Federal Rules of Evidence pertains to disclosing the bases upon which an expert opinion is based.  In 1975, when the Federal Rules of Evidence were first enacted, one of the important changes to the common law rules of evidence was that under Rule 703.  The rule provide experts could base an opinion not only on facts which were in evidence, but also on facts that were not in evidence, and even on facts which might not even be admissible if they were offered at trial, as long as these underlying facts dealt with the kind of information on which similar experts would rely in making non-litigation-oriented professional judgments. Thus, under the Federal Rules of Evidence, the prominence shifted, away from the admissibility of the facts upon which an expert’s opinion was based, to the reliability of these facts as determined by the profession in arriving at professional judgments independent of litigation. Therefore, the Amendment designed to clarify that just because an opinion may be based on inadmissible evidence that does not make the underlying information therefore admissible.

Naturally, the amendment only applies to the “proponent” of certain evidence. The opponent or contestant may freely inquire into the underlying facts upon which an expert’s conclusion is based.

III. Rule 701. Opinion Testimony by Lay Witnesses

Rule 701 was also changed, dealing with opinion evidence by ordinary fact witnesses.  Lay witnesses may be permitted to offer opinion evidence in cases where ordinary persons would typically relate their recollections of events in a conclusory matter. Thus, courts permit lay witnesses to offer opinions like, “he appeared to be drunk,” “he was going much, much faster than the 10 MPH speed limit,” “it smelled like rotten eggs,” etc.  The focus in the amendment is on “lay testimony” and “expert testimony.”  It is possible for a witness to have information available on which he or she could provide lay as well as expert opinion evidence.