Definition
The Daubert standard is the test US federal courts (and most state courts) apply to decide whether scientific expert testimony is admissible. Established in Daubert v. Merrell Dow Pharmaceuticals (1993) and refined in Kumho Tire (1999), it makes the trial judge a 'gatekeeper' charged with assessing the reliability of expert methodology before any jury hears it.
The four canonical Daubert factors ask whether the method (1) has been or can be tested, (2) has been subjected to peer review and publication, (3) has a known or potential error rate and standards controlling its operation, and (4) enjoys general acceptance in the relevant scientific community. Daubert replaced the older Frye standard, which relied solely on general acceptance.
Why it matters
Where it shows up
A Daubert hearing typically precedes trial: the proponent of expert testimony must show reliability, and the opponent can challenge methodology, validity, and qualifications. Courts increasingly require pre-trial briefs documenting the empirical basis for each claim the expert intends to make.