Describe the requirements of expert testimony both within the Frye standard and the Daubert standard.

The Frye and the Daubert standards are both ways of measuring whether an expert witness's testimony is reliable enough to be admitted into a legal proceeding in the US.
The Frye standard comes from an old federal appeals court case, Frye v. United States, from 1923. The Frye standard requires that all expert testimony come from scientific methods that are "sufficiently established to have gained general acceptance in the particular field in which it belongs."
The Daubert standard comes from much later, after many courts realized how limited the Frye standard could be. In the 1993 case Daubert v. Merrell Dow Pharmaceuticals, the Supreme Court of the United States used a different test than the Frye standard to determine the admissibility of an expert witness's testimony. In Daubert, the Supreme Court decided that, because the since-passed Federal Rules of Evidence had not referred to the Frye standard, the rules had overturned Frye. The Supreme Court then fashioned a new test, which came to be known as the Daubert standard. This new standard makes the judge a gatekeeper, with the power and duty to keep out unscientific methods that do not help the "trier of fact" (usually the jury) come to an informed decision.
Despite the Daubert standard's source in the Federal Rules of Evidence and the Supreme Court case, the Frye standard is still used in many states.
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