Technology
Admissibility of Expert Witness Testimony under the Daubert Standard
Quick fact
The Daubert standard replaced the older, stricter 'Frye rule' and shifted the judge's role from simply asking whether a technique is generally accepted to actively evaluating whether the underlying science is reliable.
Why this is interesting
In 1993, the Supreme Court changed the rules for how courts decide if an expert's testimony is admissible. But did it actually solve the problem of 'junk science' in the courtroom?
Read the full explanation
Understanding Admissibility of Expert Witness Testimony under the Daubert Standard
When an expert witness takes the stand, the judge must first act as a 'gatekeeper' to determine if that expert's testimony is reliable and relevant. Under the Daubert standard, this means examining the scientific reasoning and methodology behind the testimony, not just the expert's credentials. The Supreme Court in Daubert v. Merrell Dow Pharmaceuticals identified four non-exclusive factors: whether the theory or technique has been tested, whether it has been subjected to peer review, what the known error rate is, and whether the method is generally accepted within the scientific community. These factors provide a flexible checklist for judges to evaluate the admissibility of scientific evidence, ensuring that juries are not misled by unreliable claims.
A deeper explanation
The Daubert standard emerged from a case about a drug that allegedly caused birth defects. The plaintiffs offered expert testimony based on animal studies, but the drug company argued it was not generally accepted. The Supreme Court rejected the 'general acceptance' test from 1923 (Frye) because it was too rigid and did not align with the Federal Rules of Evidence. The Court held that judges should consider a flexible set of factors to assess reliability. This mechanism—requiring judges to understand and evaluate scientific methodology—was a significant shift. It means that in federal courts, expert testimony must be not only relevant but also scientifically valid. The standard applies to all types of expert testimony, from fields as diverse as medicine, engineering, and psychology. Its importance lies in its gatekeeping function: protecting the jury from flawed scientific evidence while not being so restrictive as to exclude novel but valid research. The Daubert standard has also influenced state courts, many of which have adopted it.