Daubert v. Merrell Dow Pharmaceuticals, Inc.
The Supreme Court ruled that the decades-old rule requiring scientific evidence to be "generally accepted" by experts before a jury can hear it no longer controls in federal court, because it was replaced when Congress enacted the Federal Rules of Evidence.
Instead, the Court held that trial judges must act as gatekeepers, screening expert scientific testimony to make sure it is both reliable and relevant before letting a jury hear it, using factors like testability and peer review rather than a rigid nose-count of acceptance in the field.
“the trial judge must ensure that any and all scientific testimony or evidence admitted is not only relevant, but reliable”
The Court's core instruction that judges must screen expert scientific testimony before trial.
How it got here: A federal trial court granted summary judgment for the drug company after excluding the families' expert evidence; the Ninth Circuit affirmed, and the families asked the Supreme Court to review the admissibility standard.
The Case in Depth
What happened
Two children born with serious birth defects, along with their parents, sued a drug manufacturer, claiming their defects were caused by their mothers taking Bendectin, a prescription anti-nausea drug, during pregnancy. The company argued that decades of published studies found no link between the drug and birth defects, while the families offered their own experts who relied on animal studies, chemical comparisons, and reanalyzed data to argue otherwise.
The question before the Court
What test should federal judges use to decide whether an expert's scientific testimony can be presented to a jury?
The Court's answer
The Court replaced the old "general acceptance" test with a new framework: federal trial judges must act as gatekeepers, checking that proposed scientific expert testimony is both reliable (grounded in real scientific methods) and relevant (actually useful for deciding the facts of the case) before letting a jury hear it.
Rather than asking whether a scientific community broadly accepts a technique, judges can now weigh several flexible factors — whether the theory or method can be tested, whether it's been published and peer-reviewed, its error rate, and whether it has standards controlling its use — with general acceptance remaining just one factor among several rather than a strict requirement.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
Every federal trial involving expert scientific testimony — from toxic tort cases to criminal forensics — now runs through the screening approach this case created. Judges, not just scientific communities, decide what science juries get to hear, which shapes outcomes in product-liability, medical, and injury lawsuits across the country.
What changes now
The case is sent back to the Ninth Circuit for further proceedings under the new reliability-and-relevance framework instead of the old general-acceptance test. The lower courts will now have to re-examine whether the families' expert evidence about Bendectin can be admitted under this approach. The decision itself is final on the legal standard but leaves the ultimate admissibility question, and the underlying lawsuit, unresolved.
What this does not decide
The Court did not decide whether the families' specific expert testimony about Bendectin should actually be admitted — that question goes back to the lower courts to apply the new standard. It also did not create a rigid checklist; the listed reliability factors are illustrative, not mandatory or exhaustive.
Concurrences and dissents
Dissent in part — Justice Rehnquist
Chief Justice Rehnquist agreed that the old general-acceptance rule did not survive the Federal Rules of Evidence, joining that part of the opinion. But he objected that the Court went further than necessary by offering abstract 'general observations' about scientific validity, testability, and falsifiability that he thought were vague, unnecessary to decide the case, and asked federal judges to referee scientific debates beyond their expertise. He would have decided only the narrow question presented and left further guidance to later cases.
How the Court got there
The legal reasoning, step by step
- The Court began by asking whether the old rule from a 1923 case — that scientific evidence must be 'generally accepted' in its field before a jury can hear it — survived Congress's later enactment of the Federal Rules of Evidence, which govern what evidence federal courts allow.
- Reading the Rules like any other statute, the Court found that Rule 702, which governs expert testimony, says nothing about requiring general acceptance, and that the Rules as a whole favor letting in relevant evidence rather than screening it out under a rigid formula.
- Because a specific rule (Rule 702) addressed the exact issue, and its text didn't mention general acceptance, the Court concluded the old rule could not survive alongside it — the Rules displaced it.
- The Court then interpreted Rule 702's requirement that expert testimony reflect 'scientific knowledge' as building in its own reliability check: the testimony must be grounded in the scientific method, not mere speculation, and must also 'fit' the facts of the case closely enough to actually help the jury.
- To guide that reliability check, the Court identified flexible, non-exhaustive factors trial judges could weigh — including whether a theory can be tested, whether it has been peer-reviewed and published, its known error rate, and whether it has attracted acceptance in the relevant scientific community.
Doctrinal impact
Cases affected by this decision
Abrogates Frye v. United States (293 F. 1013)
Replaces the decades-old rule that scientific evidence needed general acceptance in its field to be admitted.