[3] The codified use of expert witnesses and the admissibility of their testimony and scientific evidence has developed significantly in the Western court system over the last 250 years.
In this particular case, the court was hearing litigation regarding the silting of Wells Harbor in Norfolk and allowed leading civil engineer, John Smeaton, to provide scientific rationale behind the proposed legislation.
[4][5] Expert witnesses are called upon in the court system to serve as an objective party to the lawsuit and never function as an advocate for one side or the other.
Expert witnesses are present in litigation to explain complicated scientific issues, not to influence the jury or judge with fervor.
The main responsibilities of expert witnesses are to evaluate potential problems, defects, deficiencies, or errors only when able to fully appreciate a process or system.
Typically, experts are relied on for opinions on severity of injury, degree of sanity, cause of failure in a machine or other device, loss of earnings and associated benefits, care costs, and the like.
In an intellectual property case an expert may be shown two music scores, book texts, or circuit boards and asked to ascertain their degree of similarity.
Expert witnesses are those whom the court has deemed qualified to speak on a topic to provide background to anyone on a lay jury.
Voice-mail recordings and closed-circuit television systems produce electronic evidence often used in litigation, more so today than in the past.
In the case of an expert witness, the weight of his/her evidence depends heavily on the foundation support established prior to an opinion being given.
Examples include educational background, review of scholarly works, field studies and trainings which all lead up to developing a foundation of knowledge for credibility of a testimony.
[1] Generally, under Rule 702, an expert is a person with "scientific, technical, or other specialized knowledge" who can "assist the trier of fact," which is typically a jury.
If qualified by the court, then the expert may testify "in the form of an opinion or otherwise" so long as: "(1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case."
Similar procedures apply in non-court forums, such as the Australian Human Rights and Equal Opportunity Commission.
In other words, if the expert finds evidence against their client, the opposite party will not automatically gain access to it.
[13] In the United States, under the Federal Rule of Evidence 702 (FRE), an expert witness must be qualified on the topic of testimony.
[14] Experts in the U.S. typically are paid on an hourly basis for their services in investigating the facts, preparing a report, and if necessary, testifying during pre-trial discovery, or at trial.
[16] A 2021 survey conducted by SEAK, Inc., a company that helps professionals serve as expert witnesses, revealed a median hourly rate of $500, $400, and $475 for testifying in court, case preparation, and deposition respectively.
However, the court rejected the expert's testimony, ruling that: "While courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.
"[5] Through this ruling, the judge's opinion in Frye v. United States set precedent and the standard by which expert witnesses would be utilized in the court system for decades.
Many of the courts and judges had trouble interpreting the "general acceptance" notion of a particular field in a concise and non-arbitrary manner.
FRE 702 was issued to provide a standard for expert witness testimony to be upheld by the United States court system.
For instance, in U.S. v. Williams (1978), the Second Circuit responded that "the applicable considerations [for expert witness testimony] are 'probativeness, materiality, and reliability of the evidence on the one side, and any tendency to mislead, prejudice or confuse the jury on the other.
Under the CPR, expert witnesses may be instructed to produce a joint statement detailing points of agreement and disagreement to assist the court or tribunal.
The meeting is held quite independently of instructing lawyers, and often assists in resolution of a case, especially if the experts review and modify their opinions.
In most systems, the trial (or the procedure) can be suspended in order to allow the experts to study the case and produce their results.