A Daubert Hearing is an evaluation by a trial judge on the admissibility of defined "expert," or scientific and technical, testimony and evidence. The Daubert Hearing is conducted out of the jury's presence and is usually based on a motion in limine, which occurs before the trial even begins and determines which evidence or testimony will be presented to the jury. It is most efficient if the Daubert motion take place after the discovery phase so the hearing is completed before the trial starts. [The preferred Daubert family pronounciation is 'dow-bert' rather than the French style.]
The term comes from "Daubert v. Merrill Dow Pharmaceuticals," 509 U.S. 579 (1993), a Supreme Court case which determined the standards for expert testimony as set by enactment of the "Federal Rules of Evidence" in 1975. The decision modified a previous case from the District of Columbia Court of Appeals, "Frye v. United States," 293 F. 1013 (1923), which established the "Frye test." A very important note: Daubert applies specifically to all federal courts but to only approximately half of the state courts, while the other half of the states still use the Frye test. The Daubert decision was modified by "Kumho Tire Co. v. Carmichael," 526 U.S. 137 (1999), in the sense that expert testimony is not limited to only scientific evidence and testimony, but can include other areas of expertise.
In all of the decisions concerning the issue of expert testimony, the most fundamental application is that the judge is the so-called "gatekeeper" in deciding the admissibility of evidence that may be presented to the jury. As a result, judges are placed in positions where they have to determine whether an expert really is one, whether the evidence or testimony actually applies to the case at trial, establish that the science is based on results that developed through the scientific method, or whether a technical (non-scientific) expert has relevant experience in the area at issue.
Prior to the Daubert Hearing process, it was common for courts to allow "dueling" experts who would present their evidence or testimony and then the jury would decide the relevance or accuracy of the testimony. The Frye test required that the expert testimony had to meet a standard of "general acceptance" in the specific area or subject field of the evidence. This tended strongly to exclude new or cutting edge evidence that had not existed long enough to become either generalized or accepted.
Perhaps the main advantage claimed for the Daubert Hearing is that it seems to have been effective at keeping what is called "junk science" out of the courtroom. The problem is that judges, who may be, for the most part, by nature, education and experience somewhat generally unprepared to evaluate science and technology, are required to make the decisions as to what may be junk science.
One difficulty is that the Daubert Hearing allows well-funded corporate defendants to delay and litigate plaintiffs, sequentially, and exhaust their resources. Furthermore, the criminal courts often emphasize so-called "forensic science" (fingerprints, ballistics, DNA, etc.), used for the most part by the prosecution, and plaintiffs almost never win on a Daubert motion because the methods of the experts are so rarely questioned by the courts; i.e., the judges uncritically accept the findings of the prosecution witnesses.
The Daubert Hearing, then, is a procedure that can evaluate expert testimony, scientific evidence and technical data prior to presenting it to the jury. It saves a great deal of time. The process also takes the jury out of the business of evaluating which expert has more or better expertise or which evidence is more scientific. At present Daubert applies to all federal courts and in about half of the states.