An expert witness, particularly in common law countries such as the United Kingdom, Australia, and the United States, is a person whose opinion by virtue of education, training, certification, skills or experience, is accepted by the judge as an expert. The judge may consider the witness's specialized (scientific, technical or other) opinion about evidence or about facts before the court within the expert's area of expertise, to be referred to as an "expert opinion". Expert witnesses may also deliver "expert evidence" within the area of their expertise. Their testimony may be rebutted by testimony from other experts or by other evidence or facts.

History

The forensic expert practice is an ancient profession. For example, in ancient Babylonia, midwives were used as experts in determining pregnancy, virginity and female fertility. Similarly, the Roman Empire recognized midwives, handwriting experts and land surveyors as legal experts.

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. The concept of allowing an expert witness to testify in a court setting and provide opinionated evidence on the facts of other witnesses was first introduced by Lord Mansfield in the case of Folkes v. Chadd in 1782. 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. The decision by the English Court to allow for an expert to provide contextual background and detail on a case is often cited as the root of modern rules on expert testimony.

Role

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. Expert witnesses are obligated to study the processes prior to making a survey or postpone the assignment prior to potentially missing the target due to lack of specific condition understanding. They are called to testify under the assumption that all the preparation required for a competent evaluation of the process has been made.

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. In the majority of cases, the expert's personal relation to the defendant is considered and usually adjudged to be irrelevant.

The tribunal itself, or the judge, can in some systems call upon experts to technically evaluate a certain fact or action, in order to provide the court with a complete knowledge on the fact/action it is judging. The expertise has the legal value of an acquisition of data. The results of these experts are then compared to those by the experts of the parties.

The expert has a great responsibility, and especially in penal trials, and perjury by an expert is a severely punished crime in most countries. The use of expert witnesses is sometimes criticized in the United States because in civil trials, they are often used by both sides to advocate differing positions, and it is left up to a jury to decide which expert witness to believe. Although experts are legally prohibited from expressing their opinion of submitted evidence until after they are hired, sometimes a party can surmise beforehand, because of reputation or prior cases, that the testimony will be favorable regardless of any basis in the submitted data; such experts are commonly disparaged as "hired guns."

Qualifications

An expert witness at the time of trial is qualified by the court and must be re-qualified each time that person comes to trial for the offering of opinions. The qualification is given by each trial judge and takes place regardless of prior appearances by a particular expert witness. Expert witnesses are those whom the court has deemed qualified to speak on a topic to provide background to anyone on a lay jury.

Duties in United States courts

In high stakes cases, multiple experts across several topics are often retained by each party. Although it is still relatively rare, the court itself may also retain its own independent expert.In all cases, fees paid to an expert may not be contingent on the outcome of the case.

Electronic evidence has also entered the courtroom as critical forensic evidence. Audio and video evidence must be authenticated by both parties in any litigation by a forensic expert who is also an expert witness who assists the court in understanding details about that electronic evidence.

Voice-mail recordings and closed-circuit television systems produce electronic evidence often used in litigation, more so today than in the past. Video recordings of bank robberies and audio recordings of life threats are presented in court rooms by electronic expert witnesses.

Rules of evidence and code of procedure

Hearsay rule

One important rule that applies to the expert witness but not the percipient witness is the exception to the hearsay rule. A percipient witness tells only what he/she actually knows about a case and nothing more. Percipient witnesses cannot give opinions nor conjecture regarding a hypothetical set of conditions. This covers the format of the expert's written testimony as well as their behaviour in court. Similar procedures apply in non-court forums, such as the Australian Human Rights and Equal Opportunity Commission.

Educating witness

The educating witness teaches the fact-finder (jury or, in a bench trial, judge) about the underlying scientific theory and instrument implementing theory. This witness is an expert witness, called to elicit opinions that a theory is valid and the instruments involved are reliable. The witness must be qualified as an expert witness, which may require academic qualifications or specific training.

Reporting witness

Called after teaching witness leaves stand. Usually the laboratory technician who personally conducted the test. Witness will describe both the test and the results. When describing test, will venture opinions that proper test procedures were used and that equipment was in good working order.

Non-testifying experts

In the U.S., a party may hire experts to help them evaluate a given case. For example, a car maker may hire an experienced mechanic to decide if its cars were built to specification. This kind of expert opinion will be protected from discovery by the opposing party. In other words, if the expert finds evidence against their client, the opposite party will not automatically gain access to it. This privilege is similar to the work-product doctrine (not to be confused with attorney–client privilege).

The non-testifying expert can be present at the trial or hearing to aid the attorney in asking questions of other expert witnesses. Unlike a testifying expert, a non-testifying expert can be easily withdrawn from a case. It is also possible to change a non-testifying expert to a testifying expert before the expert disclosure date.

United States

In the United States, under the Federal Rule of Evidence 702 (FRE), an expert witness must be qualified on the topic of testimony. In determining the qualifications of the expert, the FRE requires the expert have had specialized education, training, or practical experience in the subject matter relating to the case. The expert's testimony must be based on facts in evidence, and should offer opinion about the causation or correlation to the evidence in drawing a conclusion.

In 2017 Kootenai County, Idaho paid nearly $600,000 during the trial over the killing of a Coeur d'Alene police officer, with the public defenders paying approximately $311,000 for seven experts and the prosecutors paying $270,000 for three experts. 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. As for the highest amount ever billed for a single case, the median was $24,000 and the mean was just over $62,000.

The expert's professional fee, plus his or her related expenses, is generally paid by the party retaining the expert. In some circumstance the party who prevails in the litigation may be entitled to recover the amounts paid to its expert from the losing party.

Scientific evidence

In law, scientific evidence is evidence derived from scientific knowledge or techniques. Most forensic evidence, including genetic evidence, is scientific evidence.

Frye test

The Frye test, coming from the case Frye v. United States (1923), said that admissible scientific evidence must be a result of a theory that had "general acceptance" in the scientific community. This test results in uniform decisions regarding admissibility. In particular, the judges in Frye ruled that:

: Just when a scientific principle or discovery crosses the line between experimental and demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recognized, and 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.

In 1923, the case of Frye v. United States instituted significant change to both criminal and civil law by addressing the use of expert witness testimony in conjunction with scientific testimony. In Frye v. United States, the defense team attempted to introduce both the results of a polygraph test administered to Frye to determine Frye's innocence as well as the testimony of an expert witness to verify and explain the results.

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."

The Federal Rules of Evidence

In 1975, the United States Congress issued the Federal Rules of Evidence. FRE 702 was issued to provide a standard for expert witness testimony to be upheld by the United States court system. The rule specified that the application of expert witnesses had to be attributed to a person with "scientific or technical knowledge," in conjunction with a list of qualifications that would quality one to be an expert in terms of "knowledge, skill, experience, training or education". The rationale in the Williams case was later adopted by other federal courts, including the Third Circuit which adopted a "reliability" test in 1984.

  1. "Whether the expert's theory or technique can be (and has been) tested"
  2. "Whether the theory or technique has an acceptable known or potential rate of error"
  3. "The existence and maintenance of standards controlling the technique's operation"
  4. "Whether the theory or technique has attained 'general acceptance'"

In 2012, twenty-two states used the Daubert test when analyzing their own expert witness rules.

Scotland

In Scots law, Davie v Magistrates of Edinburgh (1953) provides authority that where a witness has particular knowledge or skills in an area being examined by the court, and has been called to court in order to elaborate on that area for the benefit of the court, that witness may give evidence of his/her opinion on that area.

Comparison of English and US law

Similarities

Purpose

  • England and Wales: Expert evidence is to furnish the judge or jury with necessary scientific criteria for testing the accuracy of their conclusions
  • United States: Expert evidence is admissible on the basis that the knowledge will help the trier of fact to understand the evidence or to determine a fact in issue

Qualification

  • England and Wales: Expert witness is qualified to give evidence, where the court itself cannot form an opinion and special study, skill or experience is required for the purpose
  • United States: An expert witness is qualified by knowledge, skill, experience or education

Admissibility of evidence

  • England and Wales: Expert evidence must be provided in as much detail as possible in order to convince the judge that the expert's opinions are well founded
  • United States: Expert testimony is to be based on sufficient facts, data or products of a credible source of test and tried principles and methods

Differences

Conduct

  • England and Wales: Expert's "duties to the Court override any obligation to the person from whom they have received instructions or have been paid by"
  • United States: Expert's duty is not formally defined under the Federal Rules of Civil Procedure / Evidence

Depositions

  • England and Wales: Expert evidence is examined before the judge (or arbitrator)
  • United States: Expert evidence can be compelled to deposition

Ultimate issue

  • England and Wales: Expert opinion on the ultimate issue is not admissible
  • United States: Expert opinion on the ultimate issue is admissible

Turkey

During a Erdoğan-Gollum comparison trial, a panel of expert witnesses had to decide on the character of Gollum.

See also

  • Ambush defence
  • Daubert standard and Daubert v. Merrell Dow Pharmaceuticals, Inc.
  • Death of an Expert Witness - a novel
  • Employment consultant
  • Expert shopping
  • Forensic accountant
  • Forensic economics
  • Forensic engineering
  • Forensic science
  • Forensic psychology
  • Forensic video analysis
  • Frye standard of evidence
  • Gibson's law
  • In limine
  • Jones v Kaney — English caselaw abolishing witness immunity from civil action for negligence
  • Kumho Tire Co. v. Carmichael
  • Questioned document examination
  • R v Mohan — Canadian case law establishing qualifications for expert witnesses
  • Saisie-contrefaçon
  • Traffic collision reconstruction
  • Ultimate issue

References

Bibliography

  • Bronstein, DA, Law for the Expert Witness, CRC Press,2nd Ed (1999).
  • Dwyer, D, The Judicial Assessment of Expert Evidence, Cambridge University Press (2008).
  • Jasanoff, Sheila, Science at the Bar: Law, Science, and Technology in America (Cambridge, Massachusetts: Harvard University Press, 1997).
  • Reynolds, MP and King, PSD, The Expert Witness and his Evidence, Blackwell (1992).
  • Smith, D, Being an Effective Expert Witness, Thames Publishing (1993).
  • Expert Testimony in Federal Civil Trials: A Preliminary Analysis (pdf) (Federal Judicial Center, 2000)
  • Project on Scientific Knowledge and Public Policy. Daubert-The Most Influential Supreme Court Ruling You've Never Heard Of (pdf)
  • Kenton K. Yee, Dueling Experts and Imperfect Verification, 28.4 International Review of Law and Economics, 246-255 (2008)
  • Cole, Simon A. "Where the Rubber Meets the Road: Thinking about Expert Evidence as Expert Testimony" (Archive). Villova Law Journal. Villanova University School of Law. Volume 52, Issue 4, Article 4. p. 803-840.