How to prepare expert witnesses for the stand

It is commonly believed that competence in a particular field of expertise automatically translates to success on the witness stand. In reality, the scientific realm is often vastly different from the seemingly inexplicable machinations associated with a criminal or civil trial. While the expert has considerable control over what happens in the laboratory setting, the same cannot be said for the courtroom. As with many challenges, preparation is the key to success.

Experts who spend years developing and honing their scientific knowledge, and little or no time learning the skills of being an expert witness, are denying the court the full value of their evidence. This is important, because if the court does not get the full value of the expert evidence, justice may not prevail. Effective communication on the witness stand is central to the role of the expert, particularly in a forensic setting.

At its most basic level, courtroom testimony is a straightforward task. The witness has information to give to the jury. Attorneys ask questions to elicit this information and other attorneys critique that information. Yet, there is much more to this process than just the imparting of information.

When testifying in court, experts will be asked many questions by attorneys. Some questions are designed to bring forth his or her work and opinions, while others are specifically designed to challenge the expert and cast doubt on the methodology used, and the veracity of the findings. An expert witness should consider their role to be that of a teacher, educating the jury about his or her work and findings.

From a power and control perspective, a cooperative attitude is commonly promoted between the attorney and the expert witness. The attorney wants the witness to be convincing and present all relevant information before the jury. The attorney gives the witness time, attention and deference. He or she readily shares the power of “having the floor.”

Direct examination provides the opportunity for the attorney to convey to the court via the expert all of the evidence that the witness has to offer. How it is presented can go a long way toward making that testimony most effective. Direct examination should be a comfortable process for the expert witness. Rarely will there be any surprises or questions that are difficult to answer, provided the witness is properly prepared.

In contrast, cross examination includes questions with a different purpose than the questions raised during direct examination. The positive impression that the expert makes during direct examination should carry into cross examination.

Most experts dread cross examination because at times it can be quite unpleasant. But it doesn’t have to be. With proper preparation, planning and practice, even a challenging cross examination can be managed without harm to the expert’s integrity, reputation or evidence.

Cross examination involves parties with competing interests. The defense attorney’s chosen approach is dependent upon whether the evidence hurts the defense, helps the defense or is neutral.

Where the evidence hurts the other side, an interesting event occurs. The witness wants to be convincing and credible. The cross examining attorney wants to somehow devalue the evidence of the witness. Questions are asked and answered, sometimes subtly, sometimes not. Here, too, is a battle for power and control.

The power struggle

If the cross examining attorney has the witness under control, the attorney will direct the flow of the testimony, accurately anticipate responses and shape the feel and substance of the discussion. If the witness is in control, the answers will conform to what the witness believes to be correct, not the suggestions of the attorney. The witness will accurately anticipate the questions of the attorney and the witness will be in control of their own testimony.

The struggle for power and control takes place in many ways. Thorough preparation for court by either the witness or the attorney can make a significant difference in gaining control. Knowledge of the subject matter has the same effect.

Attorneys at their best are in absolute control. When that happens, the attorney knows it, the witness knows it and everyone in the courtroom knows it. The attorney is bolstered by the control over the witness and the evidential force of the witness is typically diminished.

The landslide

When a witness does not understand what is happening in cross examination, they have difficulty coping. Whatever they say during cross examination somehow makes the situation worse, but the witness is not sure why things are going downhill, let alone how to stop it. The witness may tend to attribute this to tricky attorneys, lack of preparation or nervousness. A witness who truly follows the flow of the cross examination is in an excellent position to cope with it, and sometimes profit from it.

The stronghold

A witness can sometimes maintain power and control, even when the attorneys try to wrestle it away. It is not necessary to be in control to do well in the courtroom, but it is important not to feel controlled and to be comfortable with your level of performance. A witness’ minimum objective should be to resist being controlled. This allows the witness to comfortably defend his or her observations and conclusions. Maintaining control is a greater aspiration (and is more difficult to achieve). If successful, such mastery of the courtroom can be profoundly satisfying.

An expert witness who is well prepared for cross examination and performs well will generally find a cross examination that is less unpleasant. Furthermore, a cross examining attorney will be cautious in questioning a well prepared and competent witness. The attorney may not score many points, and they certainly don’t want to lose points.

Train to win

The most valuable thing an expert witness can do to prepare for giving expert testimony is to undergo competent expert witness training. Expert witnesses and those who manage crime labs would be remiss in acquiring subject matter expertise, but not taking the next step to learn how to convey their valuable information to the court in the most effective manner.

It would be paradoxical for an expert to spend years developing knowledge and proficiency in their particular field of expertise, yet not spend any time learning how to be an effective witness. After all, it is the courtroom where the expert will truly be tested.


Jonathan W. Hak, Q.C., Dipl., B.Sc., LL.B., LL.M. (Cantab.) received his legal education in the United States, Canada and the United Kingdom. He works as a Crown Prosecutor in Canada where for the last 25 years he has examined and cross examined hundreds of expert witnesses. He teaches law in the United States and Canada, as well as courses on expert witness testimony.