Daubert v. Merrell Dow Pharmaceuticals is the seminal case involving the admission of scientific expert testimony. The plaintiff party consisted of the parents of two minor children who claimed that the mother’s ingestion of Benedictin caused the children to have birth defects. The trial court granted summary judgment for Merrell Dow based on an affidavit signed by an expert, which stated his opinion that Benedictin was not a risk factor in developing birth defects.
Daubert responded with their own expert testimony that the drug can cause birth defects. Their expert testimony was based on animal studies, chemical structure analyses, and the unpublished “reanalysis” of previously published human statistical studies. The trial court held that their evidence did not meet the standard for admission of scientific evidence. The Court of Appeals affirmed the decision and based their decision on Frye v. United States, 54 App. D.C. 46, 47, 293 F. 1013, 1014, which had been the test for admissibility of scientific evidence until this opinion. The Frye test states that scientific evidence is admissible if it is generally accepted in the scientific community.
The Frye case involved evidence derived from a systolic blood pressure deception test. Many people thought at the time that the case did not properly define the line between experimental and widely accepted science. Daubert argued that the Federal Rules of Evidence, which had been changed since the Frye opinion had been issued, are the controlling standard for the admissibility of scientific evidence in federal court and the Court agreed.
Rule 702 was the specific rule of evidence that issue, which states, “If 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.” The court reasoned that the general acceptance theory of admissibility was not included in rule 702.
Rule 702 places the responsibility on the trial court judge to ensure that the scientific testimony or evidence that is admitted into evidence is reliable and relevant. That determination looks to the methods the expert used to arrive at scientific conclusions rather than the conclusions themselves. The Court specifically contemplated the word “science” in the rule implies that the science is based on knowledge obtained through application of the scientific method. The goal is weed out more theoretical or experimental science. This is primarily accomplished by generating hypotheses and testing them to see if they can be falsified.
The Court reasoned that peer review and publication are key ways to determine that scientific knowledge is reliable. However, the Court also stated that publication alone does not render an opinion admissible because there is unreliable science that has been published and reliable science that has not. However, if the methodology has been scrutinized by the scientific community and approved, there is a basis to consider it “good science” because any flaws in the methodology will likely be found.
The Court also reasoned that the trial judges should consider the error rate of the scientific technique. Methods with high error rates should be avoided, whereas methods with low error rates are more trustworthy.
Lastly, general acceptance within the scientific community, as established in Frye, can also have bearing on the admission of scientific evidence. Here, scientific methods which have only minimal support in the scientific community may raise concerns to the court. The opinion notes that: experts may rely on hearsay in coming to conclusions; that the court can hire its own expert witness; and that to perform a 403 test, weighing scientific evidence for its probative value is substantially outweighed by its prejudicial effect.
Concern was raised that movement away from the Frye standard would result in a free-for-all. Yet, the Court found that cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof can easily alleviate those concerns. If a mistake is made, the court can correct it by directing the verdict.
The Court distinguished between the scientific and legal searches for truth, stating that science is open-ended while legal disputes must be resolved quickly and with finality. The Court noted that if the judge is to be the gatekeeper of scientific evidence, it will sometimes lead to the judge taking away meaningful information from the jury. The Rules of Evidence seek not to engage in an “exhaustive search for cosmic understanding,” but instead, the resolution of legal disputes.
The Court ultimately held that general acceptance is not a necessary precondition to the rules of evidence, and that Rule 702 assigns the trial judge the task of ensuring that expert testimony is based on reliable foundation. As a result, the Supreme Court reversed the opinion of the Court of Appeals and remanded the case for further proceedings.
The dissent argued that the Court went beyond the questions raised by the parties and that Frye was not necessarily abrogated by Rule 702.
After the Daubert opinion was handed down, Rule 702 was amended to read:
A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:
(a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue
(b) the testimony is based on sufficient facts or data
(c) the testimony is the product of reliable principles and methods
(d) the expert has reliably applied the principles and methods to the facts of the case
The rule now clearly contains the factors raised in the Daubert opinion and is now the standard for the admission of scientific evidence in federal court. Many states have also adopted the Daubert standard for the admission of scientific evidence in state court.