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Illustration of Non-Party Expert Evidence

If you have become disabled or injured as the result of an accident, the opinions of medical experts hired by insurers may become a barrier to your case. In addition to the treatment and assessments provided by your own doctors, you will have to undergo independent medical assessments (IMEs) scheduled by your insurance company. This blog will explain how the court can treat the opinions of professionals hired by insurers and how their opinions might affect your case.

What Is a Non-Party Expert? If your personal injury lawsuit proceeds to trial, experts may be called as witnesses. If the expert has been hired by your lawyers or the lawyers for the other side of the lawsuit, they are called litigation experts. This means that under Rule 53.03 of the Rules of Civil Procedure, they will need to prepare a report with their opinions on the matter and what assumptions, research and documents were used to come to this expert opinion. This report must be given to all parties in the lawsuit well in advance of trial to give an outline of the evidence that will be heard. This is different from a non-party expert who was not hired by any party in your case. For example, if your insurance provider asked you to complete a medical assessment by its doctor to determine your coverage, this insurer could choose to have that doctor attend at Trial as a witness. These types of witnesses are not required to submit a report in advance under Rule 53.03 since their opinions will be based on observations made up to their last meeting with you. These opinions are typically found in medical reports that are available to all parties in the course of litigation. What Happened in St. Marthe v O’Connor? In 2021, the Ontario Court of Appeal was asked to review what type of opinion evidence from a non-party expert can be admitted at Trial. In this case, a cyclist had been struck by a car, and there were questions about how his injuries affected his ability to work. The car’s insurer called a doctor as a witness to speak about the report he had made. In this report, the doctor stated that the injury had resulted in the cyclist’s inability to perform expected duties at work or partake in recreational activities without pain. In cross-examination, the driver’s counsel asked questions about how the injury could affect the cyclist’s ability to return to work in construction and his ability to play soccer. Counsel asked the doctor if he agreed that the muscle spasms were non-disabling and would not have prevented someone from working. The cyclist’s counsel objected to the questioning, saying that the doctor’s initial report did not deal with whether the cyclist could work, but dealt with the pain he might experience in his daily activities. Ultimately, the trial judge found that the cross-examination was unfair in that it asked for opinions outside of the doctor’s initial report. The judge discharged the jury and proceeded on a judge-alone basis, at the end of which he found in favour of the cyclist. The driver appealed this decision by saying that the trial judge erred in finding that the doctor’s cross-examination was improper and that the evidence should have been admitted. The Ontario Court of Appeal ended up agreeing with the trial judge’s decision and ruled that if non-party experts are to give evidence beyond what was made through their observations, they will need to be presented as regular litigation experts and follow those procedures of submitting a report in advance of the trial. How Could This Affect Your Case? Going forward, counsel in personal injury trials will need to be conscious of what evidence they adduce from non-party experts. The courts do not wish to allow ambush attacks where evidence is being raised at trial that has not been disclosed well in advance. If the expert in question has opinions which were not included in their initial findings, but that may help your case, you will need to treat them as litigation experts and have them prepare an additional report pursuant to Rule 53.03 for those opinions to be admissible. On the other hand, if the insurer’s representative in your lawsuit seems to be trying to get the non-party expert to admit something new which was not part of their observations, then it is good practice to object and let the judge decide whether this new evidence should be admitted.


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