Becoming qualified as an expert witness for the first time is a significant accomplishment for an expert.  External validation by a judge launches the expert to the next level as the expert enters a forum wherein he/she will be able to explain in detail the work that has been done in the case and the conclusions that have been reached.  Beyond that, the expert will face questioning by opposing counsel which can be quite challenging at times.

Later posts will focus on testimonial tips but before we get there, it is helpful to understand when attorneys are legally allowed to call an expert witness at trial.  Attorneys cannot call experts whenever they choose – there are specific legal criteria that must be met.  Before expert evidence can be admitted at trial, the court must be satisfied that four requirements have been satisfied (R. v. Mohan (1994), 89 C.C.C. (3d) 402 (Supreme Court of Canada)).

First, the proposed expert evidence must be relevant to an issue that is before the court.  Even the most interesting expert evidence will not be allowed if the preliminary relevance test is not met.  Second, the trier of fact must actually need the evidence of an expert in order to form a correct judgment about the evidence presented in the case.  In a homicide case I prosecuted, defense counsel attempted to call an expert witness who, it was claimed, would be able to assist the judge in evaluating the competing eyewitness accounts in the case.  The proposed witness was neither an expert nor was his evidence necessary in any event.  The very role of the trier of fact is to sort through the evidence and make determinations as to what evidence is preferred.  Expert assistance is not required.

Third, the proposed expert evidence cannot be the subject of an exclusionary rule that would make the evidence inadmissible.  For example, in both Canada and the United States, polygraph result evidence is not admissible and so polygraphers cannot be called as expert witnesses for the purpose of testifying as to the results of a test.  Fourth, the proposed expert must have the necessary qualifications for the field of expertise tendered.

A further requirement which focuses on the quality of the expert opinion as a pre-condition for admissibility is set out in Rule 702 of the Federal Rules of Evidence and parallel provisions at the state level.

If scientific, technical or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise, if

(1) the testimony is based upon sufficient facts or data

(2) the testimony is the product of reliable principles and methods, and

(3) the witness has applied the principles and methods reliably to the facts of the case.

When seeking to be qualified as an expert witness for the first time, the responsibility of the attorney and the proposed expert is substantial.  The ability to convince the court that the proposed field of expertise is reliable and worthy of consideration and that the tendered expert is worthy of an expert witness designation is dependent on four things:

• The ability of the expert witness to effectively communicate his/her qualifications and the substantive expert evidence to the court.
• The knowledge and skill of the attorney in leading and defending the evidence.
• The quality of the expert evidence itself.
• The credentials and suitability of the expert witness.

I have tendered expert witnesses before the court innumerable times during my career, many of them for the first time.  It is very gratifying to be able to present an expert witness before the court for the first time and to have the expert qualified to give expert evidence.  Accomplishing this salutary goal requires teamwork and preparation.  It is certainly worth the effort as expert witnesses can be pivotal in the outcome of a case.