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Law 101: Legal Guide for the Forensic Expert

Fundamental Guidelines for Deposition and Trial Testimony

Instructions for Witnesses Before Giving Testimony

The following guidelines will help make the expert's testimony more effective, more persuasive and less complex. These suggestions are based on trial-tested experience with many expert witnesses in many different cases. The guidelines apply whether the expert is testifying on deposition, in court for testimony, at a hearing, or in some other dispute resolution proceeding. The testifying expert should consider these fundamental suggestions:

  1.  Tell the truth.
  2.  Prepare for testimony by reviewing the facts.
  3.  Remember that most questions can be answered by saying:
    •  "Yes",
    •  "No",
    •  "I don't know",
    •  "I don't remember",
    •  "I don't understand the question,"
    •  or by stating a single fact.
  4.  Answer "yes" or "no" whenever acceptable.
  5.  Limit an answer to the narrow question asked. Then stop talking.
  6.  Never volunteer information or answers.
  7.  Do not assume that an answer must be offered for every question.
  8.  Be cautious of repeated questions about the same point.
  9.  Never lose your temper.
  10.  Speak slowly, clearly and naturally.
  11.  Establish a forward, upright and alert posture.
  12.  Provide verbal answers; do not nod or gesture in lieu of a verbal answer.
  13.  Do not be afraid to ask for clarification of unclear questions.
  14.  Do not be afraid of the examining attorneys.
  15.  Be accurate about all fact conditions, evidence testing and lab results.
  16.  Restrict answers to facts personally known to the expert.
  17.  State basic facts only, not opinions or estimates, unless they are requested.
  18.  Be cautious of questions that include the word "absolutely" or "positively."
  19.  Remember that "absolute" means forever, without exception.
  20.  Be cautious about time, space and distance estimates.
  21.  Do not guess, if the answer is unknown.
  22.  Do not fence, argue or second-guess the examining counsel.
  23.  Admit having discussed testimony previously, if that is the case.
  24.  Do not memorize a story.
  25.  Avoid phrases such as, "I think," "I guess," "I believe" or "I assume."
  26.  Maintain a relaxed but alert attitude at all times.
  27.  Do not answer too quickly — take a calm breath (inhale/exhale) before answering each question.
  28.  Do not look to the retaining attorney for assistance during testimony.
  29.  Make sure each question is fully understood before answering. Beware of "trick" questions.
  30.  Do not answer, if instructed not to do so.
  31.  Never joke during a deposition or testimony.
  32.  Do not exaggerate, underestimate or minimize.
  33.  Dress conservatively in clean, pressed business clothes.
  34.  Be serious before, during and after testimony.
  35.  If a mistake is made, correct it as soon as possible.
  36.  Remain silent if attorneys object during the examination.
  37.  Listen carefully to dialogue between attorneys.
  38.  Avoid mannerisms that signal nervousness.
  39.  Do not use technical language without translating it for a lay audience.
  40.  Speak simply.
  41.  Do not discuss the case in the hallways or restrooms.
  42.  Do not converse with opposing parties, attorneys or jurors.
  43.  Tell the truth.

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