Guidelines for the Expert Witness

The expert witness has special knowledge or skill which may be summoned to court to give an opinion during a trial, based on that person's field of expertise.7 min read


The expert witness has special knowledge or skill gained by education, training or experience and may be summoned to court to give an opinion or expert evidence during a trial, based on that person's field of expertise. Pre-trial preparation by the expert witness refreshes the level of expertise, enhances the quality of the opinion expressed, reduces stress and saves time. This paper outlines what preparations the expert witness should undertake before attending court and suggestions for giving testimony.

The rules governing the admissibility of expert testimony are the domain of the lawyer and the trial judge. It is unnecessary for the expert witness to be familiar with the intricacies and nuances of expert testimony and its frequent partner, hearsay evidence. It is enough to say that the admissibility of expert evidence is predicated on the existence of knowledge and experience that is beyond that of the ordinary citizen and is applicable to the matter before the court. It has the effect of proving facts.

Pre-Trial Preparation

In general terms, any person may be summoned to testify as an ordinary citizen to describe a circumstance seen and perhaps personally heard. This person has no special status. A person may also be summoned as an expert witness, in which case the witness has special status and may give opinion evidence based on the expertise of the witness. These guidelines concern the latter. This witness may be examined about his or her professional credentials and depth of knowledge, the facts of the particular matter before the court and any opinions the witness may have as to cause and effect.

Guideline 1: Attend by court-ordered summons or subpoena only.

The expert witness attends court at the request of a party or by court summons or subpoena. The expert witness should consider being formally ordered to attend rather than attending voluntarily. There are advantages to attending by court order.

The distinction between the two is significant. Testifying voluntarily raises the spectre of supporting the party who asked the witness to attend, the perception of a loss of objectivity and hence bias. A biased witness is of limited value to the court. Objectivity based on sound professional principles applied to the particular issue before the court is expected of the expert witness. A subpoena or summons compels the witness to attend and testify at the order of the court. The witness must answer questions. The order permits independence and the perception and probability of objectivity. It lessens the appearance of bias.

Guideline 2: Take to court only what the subpoena requires.

Read the summons or subpoena to find out what must be taken to court. If the order instructs the witness to attend in person, that is all that is necessary. If it requires attendance plus the bringing of files, documents or other materials, take only what is specified. If the testifying witness looks at notes to answer an inquiry or is given permission to read a document to aid with testimony, and that document was not required, the witness may be asked or required to give up that document to the court or counsel for study. The document or notes may then become subject of further examination by counsel or the court. Notes or documents prepared at the time observations were made, have more evidentiary value than those made later from memory.

Guideline 3: Clarify precisely what area of expertise is expected.

Most requests to testify as an expert witness begin with a telephone call from counsel. Clarify why counsel requires expert opinion and what expertise may be possible. Reach an understanding of the expertise required. It will focus preparation if the request is written and reduce misunderstanding later.

Guideline 4: Clarify if a written report is required.

Written reports form the basis for pre-trial preparation, settlement negotiations, and testimony during the trial. They may lead to a decision not to call the expert witness, or a settlement and hence prevent a trial. Reports may be a few paragraphs or voluminous. If a written report is requested, incorporate only what is necessary. Gratuitous and unimportant comment is to be avoided. If a report requires permission, consent or a waiver of confidentiality, insist that counsel get the proper authorization. Determine any due date for the report and to whom it is directed.

To prevent misunderstandings, a request of counsel a list of questions or an outline of the issues the report should address. As a minimum, the report should identify the reason for the report, the matter to be explored, the witness's observations and rationale, and other significant information and sources. It should state any conclusions the witness may have reached based on the observations and information. Take a copy of the report when attending to testify.

Guideline 5: Review the file and relevant information.

Testifying may occur any time after initial communications and written reports are submitted. Before attending court, review the specific circumstances to refresh memory, focus attention on important facts and issues to enhance the credibility of testimony.

Guideline 6: Ask for a convenient time to attend.

Trials requiring expert testimony may be time-consuming. Expert witnesses have other duties. Counsel is responsible for planning and presenting their evidence, including the testimony of witnesses. Although it may not be granted, the witness may request of counsel, a convenient time to testify. Counsel can estimate how long the witness may expect to be at the court.

Guideline 7: Clarify what pre-trial involvement is contemplated.

Find out what meetings with counsel or pre-trial proceedings such as discoveries, are necessary, under what circumstances and who will make the arrangements.

Guideline 8: Clarify if other experts are being called to testify.

Expert witnesses do not always agree on the interpretation of the effects of specific circumstances or facts. The witness should be prepared to respond to a challenge of his or her opinion through another expert witness. Counsel must share witness lists. It may enhance the quality of the evidence, if the witness has some understanding of a challenge, what it may entail and prepare to respond.

Guideline 9: Prepare a current curriculum vitae.

Opinion or expert testimony is permitted only if the court declares a witness to be an expert in a specified field. The declaration is made after the witness is sworn in and before testifying. Education, training, related experience and current knowledge are essential ingredients to be a credible expert witness. A declaration flows from two sources - the curriculum vitae and oral examination of the witness's credentials. An oral examination is time-consuming. A precise, uncomplicated and simple curriculum vitae, available to counsel before attendance, may lead to the uncontested declaration of the witness as an expert, shorten or focus, oral examination. The curriculum vitae should include academic training, certificates and licenses, employment experiences and publications germane to the opinions to be expressed under testimony. If elaboration of qualifications is required, the court or counsel may ask for these during the declaration stage of the hearing.

Guideline 10: Determine Legal Protection for Testimony

Because professional persons function under codes of ethics and confidentiality, insist on clear understandings of what protection the court may provide and how it is provided, for potential breaches of the code of ethics that may arise during testimony. Written confirmation from counsel outlining the protection, should be obtained before testifying.

Testifying at the Trial

The prepared expert witness will be objective and base opinions and interpretations of sound professional knowledge. The quality and hence weight is given to the witness's testimony will depend on credibility. Remember the court requires interpretation and understanding of professional opinion. During testimony, if there is an objection to the testimony of the witness, the court will instruct the witness whether or not to answer the inquiry and in what manner.

Guideline 11: Answer questions in plain language.

The expert witness attends court to interpret and express opinions about facts. Plain language will aid the court to understand interpretations and opinions. It will tell the court that the witness understands the subtleties of the profession without resorting to professional jargon. Jargon may lead to further questioning resulting in confusion and perhaps a loss of credibility.

Guideline 12: Answer only what is asked.

Be precise and do not offer gratuitous comments. Answer only what counsel or the court asks. If clarification or interpretation is needed, do so as necessary. It is better to acknowledge a lack of expertise in a specific area than to risk misleading responses. Failure to acknowledge a possible second interpretation may result in a loss of credibility. Do not assume that counsel or the court are familiar with the profession, its descriptions, and prescriptions. Assume that the evidence and the manner it is presented will be assessed for validity and weighed against other evidence.

Guideline 13: Accept the unfamiliarity of testifying rules.

The main objections raised by counsel to expert testimony arise because of hearsay and a proper foundation for the opinions expressed. Objections may be to the question asked or the answer given. When an objection is raised, the witness should refrain from speaking until the court instructs otherwise. The witness should not attempt to justify comments unless asked to do so. The witness is not to respond to an objection, argue about a comment or whether or not the evidence should be heard. After an objection is raised, the court rules on the objection and instructs counsel how to proceed.

Guideline 14: When testimony is finished, clarify status as a witness.

It is the judge who permits the witness to leave the standby excusing the witness. his means the witness is free to stay in the court or leave. The witness may, however, be required to remain for further testimony or return as the court instructs. If the latter occurs and the witness has other matters to attend, the witness may explain this to the court and ask for another time to attend. The court may or may not grant the request.


Expert testimony is an increasing phenomenon. The object of this paper has been to reduce the impact of a court summons on a profession's ability to carry out its primary goal. Pre-trial preparation and focused testimony will accomplish that end.

* The above material was excerpted, modified or otherwise prepared by the 'Lectric Law Library from 'Pretrial Preparations can Improve a Physician's Value as an Expert Witness, Can Med AssocJ, Feb. 15, 1996:573(154(4))' a work by Judge Timothy T. Daley

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