Experts are used in a wide range of litigation. Their testimony could include opinions on evidentiary evidence such as the genuineness of documents, accident reconstruction, and computer forensics. Their opinions are often viewed as critical – frequently making the difference in a case. As a result, many trials have turned into a battle of the experts.
Normally, courts prohibit witnesses from testifying based on their own opinions or analysis. See Federal Rule of Evidence 602. Courts relax these rules for expert witnesses testifying about matters within their field of expertise. While witnesses typically elicit facts at trial, expert witnesses draw opinions or conclusions from the facts.
Each party selects their own expert witness, and those experts are usually paid a fee for their consultation and their deposition and trial testimony. This fee tends to vary greatly based on the expert’s field, background, and experience.
Generally speaking, those who qualify as experts may testify about their conclusions so long as their analysis is scientifically sound, is helpful without usurping the role of the judge or jury, and are based on their background and experience. See Rule 702. In reaching their conclusions, experts may perform independent examinations of a party, make site visits, review evidence, in forming their opinion. Experts may rely on the same sorts of evidence that people in their profession normally rely on in their work, even if the evidence is otherwise inadmissible in court. For example, a doctor may testify about his analysis of X-rays, even though the X-rays would normally be hearsay. See Rule 703 of the Federal Rules of Evidence.
Expert Witness Rules
The state rules regarding expert witnesses vary by jurisdiction. This includes differences in the procedures for demanding the exchange of experts, their designation, declarations, and depositions. All states in some form require that the parties provide a brief statement of the general substance of the testimony that the expert is expected to give. Enough information must be given to put the opposing party on notice of expert’s testimony, so that opposing party can select its own expert and meaningfully prepare to depose the designated expert and examine him/her at trial. The courts have the ability to sanction a party, and exclude expert witnesses who are not property designated.
While not every state requires the expert to prepare a report, at the Federal level, all experts must prepare a report summarizing their analysis and conclusions and share the report with all other parties. See disclosure; Rule 26(a) of the Federal Rules of Civil Procedure.
Some parties retain individuals as “non-testifying experts” to help evaluate the merits of a case. Disclosure of such an expert would not be required, and their opinions would be protected from discovery. This privilege is similar to the work product doctrine, which protects materials prepared in anticipation of litigation from the opposing party.
Qualifying an Expert Witness
The court serves as a “gatekeeper” to screen out experts who are unqualified, their expertise is irrelevant to the facts at issue, or their methods are unreliable. Usually, the court will determine the admissibility of an expert witness’ testimony in a pre-trial hearing.
The U.S. Supreme Court established the standard for expert testimony admissibility in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993). In this case, the Court established guidelines for determining the admissibility of expert witness testimony. These factors to be considered are: (1.) Whether the theory or technique in question can be and has been tested; (2.) Whether the theory has been published and subjected to peer; 3. The error rate is known; (3.) Its known or potential error rate; (4.) Is there the existence and maintenance of standards controlling its operation; and (5.) Whether the theory has attracted widespread acceptance within a relevant scientific community. This is known as the Daubert Standard.
Under Federal Rule of Evidence 702, an expert can testify if scientific, technical or other specialized knowledge will assist the judge or jury to understand the evidence or to determine a fact in issue. A person who is designated as an expert witness must be qualified on the subject of his or her testimony. In determining whether the expert is qualified, the Federal Rules requires that the expert have had specialized training, education, and/or practical experience regarding the subject matter of the case. Once qualified, the expert testimony must be based on reliable principles and methods applied to the facts in evidence.
These criteria intend to prevent unreliable or otherwise "junk science" from being heard as evidence in an expert's substantive testimony. The burden is on the proponent of the testimony to establish its admissibility by a preponderance of proof. It is possible that an otherwise admissible expert witness might offer a novel theory that itself could be subject for exclusion. An expert would have to be prepared to present the science behind the theory to be able provide an opinion on that subject. The standards for admissibility may vary from one jurisdiction to the next. Therefore, admissibility of controversial or emerging theories may change from one court to the next.
Evaluating an Expert Witness
The formal rules governing the discovery of information related to experts are fairly limited. In almost every jurisdiction, the opposing party must disclose the name and expertise of any expert that party intends to use. In addition, often the expert must disclose prior lawsuits on which he/she worked, publications, and any reports produced by that expert for the lawsuit at hand. To learn how to research expert witnesses, please see the white paper Finding and Researching Expert Witnesses and Their Testimony (January 2018).
Expert Witness Reports
Under Federal Rule of Civil Procedure 26(a)(2)(b), which governs expert witness reports in civil federal cases, designated expert witnesses are required to provide a written report unless otherwise stipulated by the court. In that report, the expert is required to provide (i) a complete statement of all of his or her opinions that expert will provide, and the basis for those opinions; (ii) what facts or data was relied upon to reach those opinions; (iii) any exhibits that will be used by the expert to summarize their opinions, or to support them; (iv) a list of all of the expert’s publications the expert has authored in the past 10 years, along with the expert’s qualifications; (v) a complete list of all of the cases that expert testified either at deposition or at trial, during the previous four years; and (vi) a statement of who much the expert will be paid for the expert’s research and for their testimony in the case.
The purpose of this rule is to provide notice to opposing counsel before the deposition as to how that expert will testify. As such, experts can be precluded from testifying if their reports are too vague, or if they are written with conclusionary statements without a supporting basis for their conclusions. It is not sufficient for an expert to state that he or she will provide an opinion on an issue. Rather, that opinion must be stated in the report, along with their supporting reasoning. Experts can also be prevented from providing testimony that is beyond the scope of their original report. In general, if an expert did not provide an opinion in a report created pursuant to Rule 26(a), that expert will not be able to testify about it at trial.