Final answer:
The Daubert standard is used to determine the admissibility of expert witness testimony in US federal courts by ensuring that such testimony is scientifically valid and relevant to the case.
Step-by-step explanation:
The Daubert standard provides a rule of evidence regarding the admissibility of expert witness' testimony during United States federal legal proceedings. This standard stems from the 1993 Supreme Court case Daubert v. Merrell Dow Pharmaceuticals, which established a guideline for federal courts to determine the validity of scientific testimony. Under the Daubert standard, judges act as gatekeepers, determining whether an expert's testimony is based on scientifically valid reasoning that can be properly applied to the facts at issue. Five criteria are commonly referenced in this evaluation: whether the theory or technique can be tested, whether it has been subjected to peer review and publication, the known or potential error rate, the existence and maintenance of standards, and whether the method is generally accepted by the relevant scientific community.
In applying the Daubert standard, courts must consider if the person supplying testimony is an expert in the relevant field and if their testimony reflects agreement with the consensus of experts. Expert witnesses must demonstrate that their findings are derived from a scientific method to ensure reliability and relevance to the case at hand. The standard serves to exclude testimony based on unsound science or mere speculation, thereby safeguarding the accuracy and fairness of the legal process, especially in cases where the stakes are high such as in a capital homicide trial where the standard of proof is 'beyond a reasonable doubt'.