Abuse of discretion is the proper standard of review of a district court's evidentiary rulings. It is very much a matter of discretion with the court whether to receive or exclude the evidence; but the appellate court will not reverse in such a case, unless the ruling is manifestly erroneous. With respect to expert testimony under the Daubert standard and the rules of evidence, the trial judge must ensure that any and all scientific testimony or evidence admitted is not only relevant, but reliable. Thus, the rules leave in place the gatekeeper role of the trial judge in screening such evidence. A court of appeals applying abuse of discretion review to such rulings may not categorically distinguish between rulings allowing expert testimony and rulings which disallow it.
After the worker was diagnosed with cancer, he brought a products liability action, claiming exposure to polychlorinated biphenyls (PCBs), furans, and dioxins produced by the companies caused his cancer. After finding the testimony of the worker's experts speculative and unsupported, the district court excluded their testimony and entered summary judgment for the companies upon ruling that, although there was a genuine issue as to whether the worker was exposed to PCBs, there was no factual dispute that he had not been exposed to furans and dioxins. The Supreme Court held that the proper standard of review was abuse of discretion and it was within the district court's discretion to exclude unreliable expert testimony.
In reviewing the decision of a Trial Court to exclude or admit expert testimony, should the appellate court apply the abuse of discretion standard?
The court have held that abuse of discretion is the proper standard of review of a district court's evidentiary rulings. Indeed, our cases on the subject go back as far as Spring Co. v. Edgar, 99 U.S. 645, 658, 25 L. Ed. 487 (1879) where we said that "cases arise where it is very much a matter of discretion with the court whether to receive or exclude the evidence; but the appellate court will not reverse in such a case, unless the ruling is manifestly erroneous." The Court of Appeals suggested that Daubert somehow altered this general rule in the context of a district court's decision to exclude scientific evidence. But Daubert did not address the standard of appellate review for evidentiary rulings at all. It did hold that the "austere" Frye standard of "general acceptance" had not been carried over into the Federal Rules of Evidence.
Thus, while the Federal Rules of Evidence allow district courts to admit a somewhat broader range of scientific testimony than would have been admissible under Frye, they leave in place the "gatekeeper" role of the trial judge in screening such evidence. A court of appeals applying "abuse of discretion" review to such rulings may not categorically distinguish between rulings allowing expert testimony and rulings which disallow it.We likewise reject respondent's argument that because the granting of summary judgment in this case was "outcome determinative," it should have been subjected to a more searching standard of review. On a motion for summary judgment, disputed issues of fact are resolved against the moving party -- here, petitioners. But the question of admissibility of expert testimony is not such an issue of fact, and is reviewable under the abuse of discretion standard.