In Daubert, the United States Supreme Court set the standards for admitting testimony about scientific evidence under the Federal Rules of Evidence.

The United States Supreme Court upheld the trial court's exclusion of evidence in the Daubert case. As part of its opinion, the Court set out four factors that the trial judge should consider in determining if evidence should admitted: such as a theory's testability, whether it "has been a subject of peer review or publication," the "known or potential rate of error," and the "degree of acceptance ... within the relevant scientific community. The Daubert court stressed that this analysis was intended to be flexible, with the trial judge determining how and whether the factors applied in a given case.

The Kumho case looks at whether the Daubert factors may also be applied to non- scientific expert testimony.[Kumho Tire Co., Ltd. v. Carmichael, 119 S.Ct. 1167 (U.S. 1999)] Kumho arose when a tire manufactured by defendant blew out, resulting in a automobile accident that injured plaintiff. Plaintiff's expert attempted to testify that defendant's tire was defective and that the defect was the cause of the blowout. Defendant objected, claiming that plaintiff's expert's method of determining whether a tire was defective was not sound and ignored substantial evidence of other causes of the blowout. The trial judge found that the plaintiff's expert's methods for analyzing the date the expert obtained from a visual analysis were unscientific and refused to allow the expert to testify. Without the expert's testimony the plaintiff did not have any evidence to support the its case of products liability and the judge gave defendant a summary judgment.

Plaintiff appealed to the Eleventh Circuit, which found that the trial judge had erred by applying the Daubert factors to non-scientific evidence and remanded the case to the trial court with instructions to reevaluate the expert's testimony without using the Daubert factors. The defendant appealed and the United States Supreme Court accepted the case for review. In its review, the Supreme Court's primary ruling was that trial judges should review evidence to assure that it was reliable and not overly prejudicial. It stressed that the trial courts have great latitude in how they do this review, and that they should be flexible in setting their standards to assure that different types of evidence get appropriate review. The court held that it was not error for the trial judge to use the Daubert standards to evaluate the expert's testimony on the nature of the defect in the defendant's tire. The court stressed that the trial judge has not just looked at the theory behind the expert's methods, but had looked to the extensive discovery record questioning these methods and the problems the expert had in determining basic information about the tire. The court makes it clear that the trial judge is not rejecting all methods of tire analysis, but is looking specifically at this expert's own variant of accepted methods and finding them inadequate. Justice Scalia's brief concurrence is a good summary of this case: " I join the opinion of the Court, which makes clear that the discretion it endorses-- trial-court discretion in choosing the manner of testing expert reliability--is not discretion to abandon the gatekeeping function. I think it worth adding that it is not discretion to perform the function inadequately. Rather, it is discretion to choose among reasonable means of excluding expertise that is false and science that is junky. Though, as the Court makes clear today, the Daubert factors are not holy writ, in a particular case the failure to apply one or another of them may be unreasonable, and hence an abuse of discretion."