Jason Daubert and Eric Schuller sued Merrell Dow for compensation for limb reduction birth defects allegedly caused by their mothers' ingestion of Bendectin, a morning sickness pill manufactured by Merrell Dow. The district court granted summary judgment for Merrell Dow based on exclusion of the plaintiffs' expert testimony. The Ninth Circuit affirmed. The U.S. Supreme Court granted certiorari and used the opportunity to overrule the Frye[1] "general acceptance" test for the admissibility of expert testimony. Based on the Federal Rules of Evidence, the Court established a two-pronged test and placed judges in the role of "gatekeepers." Under the new test, judges must first determine if the expert testimony reflects scientific knowledge, whether it is derived by the scientific method, and whether the work product is good science. The Court referred to the second prong as the "fit" requirement: the judge must then determine if the testimony will assist the trier of fact. The Court vacated the judgment and remanded to the Ninth Circuit.

The Ninth Circuit viewed the first prong of the test as requiring it to evaluate the basis, rather than the content, of the expert testimony. The court determined there must be objective evidence the expert had used the scientific method, not just his "bald assurance" he had done so.

The U.S. Supreme Court listed factors courts could use to determine if the expert had used scientific methods. These include whether scientists in general accept the methods; whether the research has been published; whether the research can be tested; and whether the potential rate of error is within reasonable bounds. The Ninth Circuit read this list as "illustrative rather than exhaustive." For its own analysis, the Ninth Circuit relied upon the following factors: whether the research was conducted independent of litigation; whether the research had been subjected to peer review through publication; and whether the expert could show that his methods were objectively accepted by at least a minority of the scientific community.

All of the plaintiffs' experts conducted their research specifically in preparation for the Bendectin litigation. The court reasoned that research undertaken in preparation for litigation is more likely to be biased than that undertaken independently. Additionally, none of the studies had been published and the only serious review the studies had received was in the courts. Furthermore, the Food and Drug Administration continues to approve Bendectin. The court reasoned if the studies had merit, scientific journals would have published them. Lastly, the experts could not point to objective sources to back up their methodologies. Despite these factors, the court generally determined the testimony was not inadmissible as a matter of law. Because the record had been developed while Frye was still the law of the circuit, the court reasoned that the plaintiffs might be able to present some additional evidence that would meet the new standard.

One of the plaintiffs' experts, Dr. Palmer, based his testimony on his belief that Bendectin was a teratogen and his examination of the plaintiffs' medical records; he offered no testable theories on which he based his conclusions. Because he testified from no "understandable scientific basis," the court held his testimony was personal opinion, not science, and struck it.

The court also held that the plaintiffs' evidence failed the second prong of the test, the "fit" test. Looking to California tort law, the court reasoned the plaintiffs would have to prove that Bendectin more likely than not caused their birth defects. Dr. Palmer testified to that, but his testimony was inadmissible under the first prong.

Because the plaintiffs had produced no admissible evidence to create a genuine issue of material fact as to causation, the Ninth Circuit affirmed the district court's granting of summary judgment in favor of Merrell Dow.