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Rules of evidence: Opinion evidence & Self-serving evidence

Is your trial date coming up?  Find out which types of witnesses you can present in court to strengthen your case!

When admitting evidence in court, evidence given by a witness under oath may be referred to as “testimony” and such testimony may be either viva voce or in written form. Viva voce evidence is when a witness is providing evidence orally and is available for cross-examination. As opposed to providing evidence in a written form, such as an affidavit, viva voce evidence may be given more weight than documentary evidence in certain circumstances.

The rule of Opinion Evidence

There are some limits on the type of evidence that a witness may present in court. Generally, a witness may only testify on matters they have actually observed. Witnesses must avoid making any opinions and inferences from the facts they have observed. This is because it is the trier of fact’s jurisdiction to draw such inferences based on the evidence that is presented.

Exceptions to the rule

As abovementioned, presenting opinion-based evidence before the court is usually not permitted. However, the exception to this rule is that opinion-based evidence may be presented by an expert witness.

The purpose in presenting expert witness evidence is to provide the court with scientific information that is outside the tribunal’s expertise and knowledge. Essentially, such expert offers its informed opinion to be helpful to the court and better the position of the trier of fact to draw inferences and make decisions.

To admit such expert testimony in evidence, the parties must indicate in the case protocol that they intend to seek one or more expert opinions, at the latest 45 days following the date on which the originating application was served. Consequently, this time limit requires the parties to assess, at the outset, whether they should obtain an expert opinion and consider the associated costs.

In addition, the witness must be qualified as an expert within a specific field prior to being permitted to testify. An expert witness can be characterized as a person who possesses a special set of skill and knowledge acquired through study or observation. Hence, all expert witnesses are required to disclose their qualifications of their expertise as it is important to assess their qualifications within that specific field.

Having established the expert witness’ field of expertise and their qualifications, they will then be entitled to provide opinion evidence through either oral or written testimony. Such written form of evidence may be in the form a report such as in medical or psychological report and will contain detailed observations and an analysis of the expert’s conclusions.

Hence, in order to shorten the duration of hearings during which expert evidence is presented, the Civil Code of Procedure of Québec provides that the expert report stands in lieu of the expert’s testimony. Thus, a party may examine the expert that it retained to further obtain particulars on specific matters within the expert’s report or to acquire the expert’s opinion on new elements that were presented during a trial. 

It is important to note that the trier of fact is however not bound to the expert’s testimony as this form of evidence will be weighed. Nevertheless, when the expertise of a witness is credible, the decision-maker will take particular care in considering it!

Self-Serving Evidence

The term of self-serving evidence is used to describe evidence that has been fabricated by a party who intends to use such evidence to advantage their own case. Self-serving evidence is generally created by a party for the purpose of the hearing and this party intends to submit this evidence to the extent that it helps and better serves their own position. 

This form of evidence is given little weight because it is self-serving by the party that created it for their own benefit. Therefore, such evidence is assimilated to a fabrication that might not reflect the true reality of the facts of a case. 

The disclosure of self-serving evidence often leads to the finding that the witness is not credible and is suspected to have embellished evidence to support his own claim. Thus, self-serving evidence does not hold probative value in a court of law and is essentially inadmissible.