Opinions and Expert Testimony

Article VI of the Michigan Rules of Evidence contains the rules dealing with witnesses. Trials bring to mind testimonial evidence. There surely are other kinds of evidence, such as docmnents, guns, automobile tires, chemical substances, and the like. But most evidence comes from the mouths of witnesses, and even demonstrative evidence usually is admitted only after a witness has taken the stand and testified to foundation facts. So it is important and appropriate that we turn to the provisions of the rules that deal with qualifications and credibility of witnesses. I would like to direct your attention to MRE 601 and 603, dealing with the competency of witnesses, and MRE 602, dealing with the requirement of personal knowledge. There are affirmative and negative aspects of competency. On the affirmative side, there are two requirements. First, Rule 601 requires the physical and mental capacity: one must have had sight to testify to what was seen or hearing to testify to what was heard; the ability to remember what was perceived by these or the other senses; and the ability to communicate understandably what is remembered. In brief, the important mental and physiological factors are the abilities to observe, remember, and communicate. The second affirmative element of competency, stated in Rule 603, is that the person must be willing to commit himself to try to tell the truth. In essence it is a moral qualification