Legal Ease, April 17
In general, witnesses are expected to say what they saw, heard, smelled or somehow perceived. They are not supposed to give their opinions about what happened.
The idea is that you put all the facts before the court and then let the court take those facts and come to conclusions about what actually happened.
This limitation on what a witness can talk about makes sense. The opinion, speculation or guess of a witness may be totally in error and the witness is in no better position to draw conclusions from established facts than the court.
All that said, there are some exceptional circumstances that allow for opinions to be given by witnesses. Usually those circumstances are where an expert is needed to understand otherwise proven facts.
An example may make things clearer.
Suppose there is a lawsuit about how someone who was ill died. The family says it was inadequate medical care and the defendant says it was a natural death. The only way to figure out what really happened is to get someone who understands medicine to testify. The evidence of medical people is necessary.
That last point makes some of the limits on expert evidence clear.
First, an expert will be allowed to testify only when the expert evidence is necessary. If the case can be understood without an expert than no expert will be allowed.
Second the expert must have real expertise in a legitimate field of study.
While the expert does not have to be a professor from the South, they must have a real expertise. And the field they have expertise in must legitimate—it must be generally accepted as a valid area of study.
Third, the expert must not be biased or a “mouth-piece” for one side or another.
A highly qualified person with lots of degrees is very impressive and what they say will be taken seriously. But if they are not impartial they will make the trial unbalanced instead of fair.
Finally the court will only hear expert evidence if, on balance, the evidence would be of greater value than the confusion it might cause—in effect the court asks how important the evidence of the expert is.
As you can see, most of the time an expert is not going to be part of a trial. But when they are needed, they are very important.
James Morton is a lawyer practicing in Nunavut with offices in Iqaluit. The comments here are intended as general legal information and not as specific legal advice.