Expert Witnesses

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Cross-Examination Toolbox

Defense counsel must be alert for circumstances in which an expert can be of use. Experts can be used in a variety of capacities. For example, medical experts can establish the time of death or the height of the individual inflicting a wound. Psychiatrists can establish insanity or diminished capacity.

  • An expert may be used only in an advisory capacity to assist in formulating a defense. The advisory expert then would not testify at trial.
  • Bring the testifying expert into the case at an early stage, so that the expert is not hindered by the passage of time and/or destruction of important evidence.

Counsel should give careful consideration to the selection of an expert. Consider the expert's stature in his field, availability, and costs for services. Try not to use an expert who derives most of his income from testifying at trials, the so-called "professional expert."

While an expert with a sound formal education, and practical experience and scholarly publications is important, it is also important to select an expert who communicates well and can "connect" with a jury.

  • Fully explain your tentative theory of defense to the expert and what you hope to prove through the expert.
  • Ask the expert for his opinion about how best to present the defense.
  • consulting one expert, an additional expert may be needed.

The defense expert at trial

  • Must be calm.
  • Must understand the rules of evidence.
  • Must be well-prepared for direct testimony and cross-examination.
  • Must give responsive answers.

Meet with the Expert

Before even considering having an expert appointed, meet with him/her in person. It is important to meet with the expert to be able to see what the expert looks like and how the expert relates to you. Most experts will be happy to give you 30-45 minutes of their time. This will give you the opportunity to see the expert and also get an idea about what the expert thinks about your issue. Finally, you will be able to ask the expert if he/she has any 'baggage' about which you should be aware. This should be done in every case and as delicately as possible.

Preparing an Expert to Testify

Before calling an expert to testify, it is important to collect and review all relevant articles, book chapters, letters, abstracts and publicly-presented PowerPoints written by the expert, and to categorize them by field. Assess the expert's education, categorize it by field and ask the expert how many times he/she has been qualified in the area of expertise relevant to your case. Review the expert's CV for areas of expertise and gaps in expertise. Talk with the expert about the areas in which you want to qualify him/her as an expert, and ask him/her the types of questions that will be asked on voir dire by the opposing lawyer, if permitted.

You should review all expert's articles related to the opinion he/she will render. Review all prior affidavits related to the opinion. Talk with the expert about the basis of his/her opinion. What data, scientific articles and/or scientific research supports the expert's view? Talk with the expert about which articles and what research contradicts his/her opinion. Why don't those articles or research affect his/her opinion?

It is important to only attempt to qualify the expert in areas in which he/she is "expert". A psychologist, John Briere, suggests: "Remember the acronym HELP which stands for honesty, evenhandedness, limit expertise and preparation". In order to effectively prepare your expert to testify, you will need to know who will testify for the prosecution and who else you will call as an expert. Make sure to inform the expert of the areas that you will ask of the other experts.

There are a number of tasks the expert must do before he/she testifies. The expert should develop an opinion based on science- i.e on research in the field of study and the views of credible peer-viewed work by (and conversations with) others. The expert must know the literature and know what he/she has said in the past (the exact wording) regarding the relevant subject matter.If the expert's views have changed, the expert should tell you this and be prepared to explain the basis of the change in his/her opinion.

Any opinion should be grounded on good science. Good science should be published in the peer-reviews literature and should be supported by other scientists. Very few experts are of sufficient reputation to be an "expert of one". Experts must know the literature and the research and be able to back up their opinions with those of other respected scientists, particularly those who all scientists would agree are world-renowned in the topic at issue.

Lawyers should explain and discuss the following with all experts regardless of their experience in testifying: The expert must know whether his/her involvement in the case is confidential , with whom the expert may discuss involvement in the case, issues relating to the case and what the expert's response should be if he/she receives a communication from anyone about the case. An expert may not present information pertaining to a particular case, even if the case is not specifically identified , at a meeting, in publications, to the media or on email listserves without the explicit permission from the attorney. The lawyer should be prepared to answer the following questions:

  • Can the expert communicate with the lawyer via email or in writing while working on this case?
  • Should the expert prepare any reports, make notations?
  • What materials can the expert rely on while testifying (notes, reports, etc)?
  • What materials should the expert bring to court?

The expert should be informed that the information should never be disclosed by him/her to the other side. The exchange of information should always be done by the lawyers. The expert should also be advised that before creating any documents, the expert should confer with the lawyer to ensure that such documents accurately and completely reflect the expert's opinion.

You should explain and discuss with the expert the background, experience and practice of the particular judge hearing the case, and the background, experience and practice of counsel on the opposing side.

You should explain leading versus direct questions and how to respond when objections are raised. You should also discuss how to respond if the questioner cuts the expert's answer off, and how to respond if the questioner does not permit the expert ti explain an answer. Finally, you should have a discussion with your expert regarding attire, demeanor and the use of humor in the courtroom While there are some occasions where hunor may be appropriate, the expert must recognize that, in general, the court is not a place for humor, informal language or off-handed remarks.

Effective preparation takes time. Both the lawyer and the expert must plan accordingly. Assess how much time it will take the expert to complete his/her review of the information. Add several hours that will allow you to discuss the issues in the case with the expert. Add several more hours to go over the anticipated direct examination and to discuss likely lines of cross-examination. Be fair in paying the expert for his/her time.

Evaluating Expert Witnesses

  • Has the expert obtained judicial permission to conduct the evaluation?
  • What evidence has the expert examined?
  • What are the expert’s fields of expertise?
  • How long has he been considered an expert in his field?
  • What are the expert’s qualifications? Has he been authorized and does he have the credentials to be an expert evaluator?
  • Is the expert equal to the work of his own field? Are the expert’s methods and techniques in accordance with the relevant national or professional standards? Has the expert used up-to-date technology to conduct his evaluation? Does the evaluation require the expert to cover subjects beyond his area of expertise or beyond the technical and evaluation capacity of the judicial expert examination apparatus?
  • Are the materials that are the foundation for the expert’s conclusions sufficient and authentic? Are the materials suitable for evaluation or assessment, or do the materials conflict with the evaluation requirements?
  • Consider whether there is a need to advise the defense expert to independently verify the evidence.
  • Does the client have any physical or mental injuries that need an expert evaluation and technical explanation? If so, apply for the court to provide expert evaluation on the client’s physical health or mental state. Provide the expert with the client’s relevant medical records and biographical data.

See Evidence