A late objection by Wawanesa cost the insurer ground at trial when an Ontario court allowed a treating psychologist to double as a litigation expert.
In a ruling released on April 22, 2026, Justice Spencer Nicholson of the Ontario Superior Court of Justice permitted plaintiff Linda Wallis's treating psychologist to testify in an expanded role during a five-week jury trial. The case - Wallis v. Wawanesa Mutual Insurance Company, 2026 ONSC 2423 - stems from a motor vehicle accident on December 22, 2016.
Dr. Anne McDermid, a psychologist who has treated Wallis for her psychological injuries over roughly nine years, was at the center of the dispute. Wallis's legal team wanted Dr. McDermid to testify not just as a treating professional offering observations from her care - known in Ontario law as a "participant expert" - but also as a litigation expert presenting broader opinion evidence from three narrative reports she had prepared.
Wawanesa pushed back. The insurer argued the reports fell short of the formal requirements under Ontario's rules for litigation expert reports. It also said the plaintiff had not sought permission to call more than three expert witnesses - the limit under Ontario's Evidence Act - and questioned whether Dr. McDermid could be impartial given her long relationship with the plaintiff.
Justice Nicholson was not persuaded. He found that while Dr. McDermid's first report from 2018 had gaps - it lacked her qualifications and did not list supporting documents - her later reports from February 2025 and February 2026 filled those holes. Read together, the three reports met the requirements. The court noted the rules should be read in a "liberal and generous manner" and pointed out that Wawanesa's own experts had already reviewed and responded to all of Dr. McDermid's reports.
On the witness limit, the court acknowledged the plaintiff had not formally sought permission to exceed the cap. But it flagged a timing problem that should concern defence teams across the industry. In earlier cases, objections of this kind were raised before trial got underway, giving plaintiffs a chance to choose which experts to call. Here, Wawanesa waited until Dr. McDermid was about to take the stand - by which point another psychologist, Dr. Iezzi, had already testified with overlapping opinions. The court found the insurer "contributed to this situation to some extent by not raising this concern at the outset of trial." Permission to exceed the limit was granted.
On impartiality, the court found that a treatment relationship does not automatically disqualify an expert. Dr. McDermid had signed an acknowledgment of her duty to the court, and her written reports showed no signs of advocacy. The court said it would continue to assess her objectivity during live testimony.
The takeaway for insurers is straightforward. Defence teams that sit on objections to expert witnesses risk losing those arguments when it matters most - at trial. Courts are also open to letting treating professionals with years of patient contact testify in expanded roles, covering diagnosis, prognosis, causation, and employability. And when it comes to formal requirements for expert reports, judges may look at the full picture rather than picking apart each document on its own.
