Proving Mental Injury

In its recent decision of Saadati v. Moorhead, 2017 SCC 28, the Supreme Court of Canada held that courts may award damages for mental injury based on the testimony of lay witnesses and without expert evidence establishing an identifiable medical diagnosis or condition.

The plaintiff was injured when his tractor-truck was struck by a vehicle driven by the defendant. The plaintiff sued the defendant for negligence, claiming he had suffered mental injury from the accident.

At the trial level, the BC Supreme Court found the accident had indeed caused the plaintiff’s psychological injury, including a personality change and cognitive difficulties. This finding was not based on an identified medical cause or expert evidence, but rather on the testimony of the plaintiff’s friends and family. These lay witnesses testified that the plaintiff was a funny, energetic, and charming individual prior to the accident, but had become sullen and prone to mood swings. His close relationships with others had deteriorated. The BC Supreme Court awarded the plaintiff $100,000 in non-pecuniary damages.

On appeal, the BC Court of Appeal reversed the trial judge’s decision, finding that the plaintiff’s claim could not succeed, as he had not demonstrated with expert evidence a medically recognized psychiatric or psychological injury.

The Supreme Court of Canada (SCC) restored the trial judge’s decision on the basis that a finding of legally compensable mental injury need not rest, in whole or in part, on the claimant proving a recognized psychiatric injury through expert evidence.

The law of negligence accords identical treatment to mental and physical injury.   As with physical injury, a plaintiff alleging mental injury still needs satisfy the criteria applicable to any successful action in negligence – i.e. the existence of a duty of care owed by the defendant to the plaintiff, a breach of that duty, and resulting harm to the plaintiff causally connected to the breach. In the case of mental injuries specifically, the plaintiff must also demonstrate that the injury is serious, prolonged, and rises above the ordinary annoyances, anxieties, and fears that come with living in civil society.

In Saadati, the SCC emphasized that a court adjudicating a claim of mental injury should not be concerned with diagnosis, but rather symptoms and their effects. There is no necessary relationship between reasonably foreseeable mental injury and a diagnostic classification scheme; rather, the court’s inquiry should be directed to the level of harm that the claimant’s particular symptoms represent, not whether a label could be attached to them. While expert evidence can assist in determining whether or not a mental injury has been shown, such evidence is not necessary, and a court can find mental injury based on other evidence, including the testimony of family and friends.

It remains open to the defendant, in rebutting a claim, to call expert evidence establishing that the accident cannot have caused any mental injury, or at least any mental injury known to psychiatry.

Based on the foregoing principles, the SCC found no legal error in the trial judge’s treatment of the lay witness testimony concerning the plaintiff’s mental symptoms, even in the absence of expert testimony associating them with an identified condition. The SCC restored the trial judge’s award of $100,000.

A good question: the Alberta Court of Queen’s Bench clarifies Questioning on Affidavit

In Alberta (AG) v Alberta Power (2000) Ltd (“Alberta Power”),[1] the Alberta Court of Queen’s Bench helpfully explains how Questioning on Affidavit differs from Questioning on Discovery, including by offering several practical examples. The case also summarizes key principles that govern the scope of Questioning on Affidavit. Moving forward, Alberta Power will likely be a common authority cited in applications to determine the validity of objections made in Questioning on Affidavit.

Questioning on Affidavit versus Questioning on Discovery

Writing for the Court, Chief Justice Wittmann explained that although Questioning on Discovery is “in the nature” of a cross-examination, it is not a “true” cross-examination as is Questioning on Affidavit.[2] This subtle distinction between the two modes of Questioning produces significant practical differences. For example, Questioning on Affidavit may involve questions that solely relate to credibility.[3] By contrast, these types of questions are generally impermissible in Questioning on Discovery.[4] Additionally, the transcript from a Questioning on Affidavit is placed before the Court in its entirety. This differs from Questioning on Discovery, in which counsel select excerpts from the transcript to “read-in” at trial.[5] These practical differences reflect the fact that the two modes of Questioning perform conceptually distinct functions in civil litigation.[6]

Principles for Questioning on Affidavit

After distinguishing the two modes of Questioning from each other, the Chief Justice then summarized the following key principles that apply to Questioning on Affidavit:

    • Questioning on Affidavit is cross-examination;
    • the scope of Questioning on Affidavit is “framed by the motion that the Affidavit is made in support of”;
    • when the motion itself is the entire law suit, such as in an Originating Notice, Questioning on Affidavit can “cover the whole lawsuit”;
    • Questioning on Affidavit may extend to matters deposed to that are irrelevant to the relief claimed; and
    • the principle of proportionality applies to Questioning on Affidavit, and undertakings ought be fulfilled if the provision of the information would not be “overly onerous” and would likely significantly help the Court determine the application.[7]


Alberta Power helps clarify how Questioning on Affidavit and Questioning on Discovery are conceptually and practically distinct. The Chief Justice also provides welcome guidance as to the scope of Questioning on Affidavit. For these reasons, Alberta Power will likely be a useful precedent for resolving objections made in Questioning on Affidavit.