Frye v. United States, 293 F. 1013, 1014 (D.C.Cir. 1923) held, in the context of a case involving the admissibility of opinion evidence based upon use of a precursor of the polygraph, that scientific evidence would be admissible only after the thing from which the deduction is made had been sufficiently established to have gained general acceptance in the particular field in which it belongs.This decision was the birth of what ultimately became known alternatively as the Frye test or the general acceptance test. While ignored initially by other courts, the Frye test would, by the end of the 1990's, become the majority test for the admissibility of novel scientific evidence. This was true in the federal courts as well as in the states, despite the passage in 1975 of Federal Rule of Evidence 702, which was believed by some courts to embody a more flexible general relevance test for admissibility of opinion testimony by expert witnesses. 

In 1993, however, the United States Supreme Court handed down the very significant decision of Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993). In Daubert, the Court stated that evidence based on novel scientific knowledge should be admissible only after it had been established that the evidence was reliable and scientifically valid. Furthermore, the Court cast upon the trial judges the duty to act as gatekeepers charged with preventing junk science from entering the courtroom. In order to assist the judges in fulfilling that role, Daubert discussed four factors: testing, peer review, error rates, and acceptability in the relevant scientific community. These four tests for reliability became known as the Daubert factors.

In 1997, in General Electric v. Joiner, 522 U.S. 136 (1997), the Court amplified its Daubert holding by adding that in reviewing the decision of a trial court to either admit or deny admission of certain expert testimony, whether on the issue of the judge's determination of reliability/ unreliability, or on the ultimate conclusion reached by an expert, a court of appeals must use an abuse-of-discretion standard. 

In the aftermath of Daubert, several issues remained unresolved and courts reached differing conclusions on these questions. One uncertainty was generated by the language used by the Court in defining scientific knowledge and by identifying four specific factors by which reliability of such knowledge was to be determined. The Court adopted a definition of scientific knowledge that was drawn from the physical sciences, and the Daubert factors, it was widely argued, were not suitable for many other types of expert testimony that depended more on skill, generalized knowledge and experience, technical prowess, or even on applied science and/or clinical judgment. Another unresolved issue was whether a Daubert inquiry would even be required at all when a court was dealing with non-scientific expert opinion evidence, or when a particular technique already had gained widespread judicial acceptance.

On March 23, 1999, the United States Supreme Court significantly enlarged the Daubert holding in the case of Kumho Tire Co. v. Carmichael, No. 97-1709.

In Kumho Tire, the Court held that the Daubert factors Amay apply to the opinion testimony of non-scientist expert witnesses. The Kumho Tire case was a diversity action against the maker and distributor of an automobile tire. The tire had blown out, which caused the minivan on which it was mounted to turn over. In the accident, one passenger died and others were injured.

The plaintiffs sought to make their case through the testimony of a tire failure analyst who wanted to testify that a defect in the tire's design or manufacture caused the blowout. The defendants sought to exclude the expert's evidence on the ground that the methodology did not satisfy Federal Rule of Evidence 702's requirements. The district court, applying the Daubert factors, agreed with defendants and granted the motion. It also entered summary judgment for defendants. While there were some intermediate procedural steps, the case ultimately reached the United States Supreme Court on the issue of whether Daubert applied only to expert evidence that was based on scientific knowledge.

Without equivocation, the Court held that the obligation imposed on trial judges by Daubert to act as gatekeepers applies not only to scientific testimony, but it applies to all expert opinion testimony. In order to fulfill its gatekeeping responsibility, a court Amay use the factors identified in Daubert IF they can be appropriately utilized to determine reliability of either the underlying technique or the expert's conclusions. But since Daubert clearly stipulated that the inquiry it asks trial judges to undertake is a flexible one, the gatekeeping function of necessity must be tied to the particular facts of a case. Thus, the factors identified in Daubert are not supposed to be talismanic, nor do they constitute a definitive checklist or litmus test. 

In this newest decision, the Court continued to grant trial judges a broad latitude of discretion. The Court permits trial judges to apply any and all useful factors, whether identified in Daubert or elsewhere, that will assist the tribunal in making a determination of reliability of proffered evidence as deemed appropriate in the particular case.