R. v. O’Rourke, 2025 ONSC 3608

Court File No.: CR-23-3605 (Chatham)
Date: 2025-06-24
Ontario Superior Court of Justice

Between:
His Majesty the King
and
Sean O’Rourke, Defendant

Appearances:
Jason A. Nicol, for the Crown
Sandip Khehra, for the Defendant

Heard: May 15, 2025

Ruling on Expert Voir Dire

Bruce G. Thomas:

Introduction

[1] The defendant, Sean O’Rourke, is being tried for the offence of manslaughter. O’Rourke is a constable employed by the Ontario Provincial Police (O.P.P.). During what O’Rourke termed a “high risk takedown” of a motor vehicle, O’Rourke’s gun discharged, killing the driver of the motor vehicle who we now know to be Nicholas Grieves.

[2] The defence seeks to call an expert witness, namely Laurence Miller, PhD., who is a licensed psychologist practising in Boca Raton, Florida. It is the defence position that this witness can provide opinion evidence on an individual’s neuropsychological reaction to complex stressful situations and how the neuropsychological response may result in a number of alterations of perception, behaviour, emotion and memory.

[3] Specifically, Dr. Miller would opine on why the defendant reacted as he did during this event and why he cannot explain how, in these circumstances, his gun discharged.

[4] The Crown argues that this evidence is inadmissible as it fails to satisfy the threshold requirement of necessity.

[5] After hearing brief oral argument in the course of this trial, I ruled the evidence inadmissible as it was neither necessary nor relevant. I promised brief written reasons to follow. These are those reasons.

Factual Background

[6] As this admissibility issue cannot be decided in a factual vacuum, I propose to provide a limited narrative on the circumstances leading up to the fatal shooting. The defendant has been employed in policing since 1986 and with the O.P.P. in various capacities and locations since 1994. He is a highly experienced front-line officer, a member of the Tactical Response Unit (TRU Team) for five years and an instructor in firearms and use of force options. He has developed an expertise in conducting traffic stops and recognizing the presence of contraband; usually drugs, guns or currency.

[7] In the early morning hours of July 7, 2021, O’Rourke and Sgt. Cook received a call from dispatch that a sedan with a loud muffler had left a nearby 401 ONroute without paying for $40 worth of gasoline.

[8] Knowing the vehicle was headed in their direction, the two officers, in separate vehicles, took up position to intercept. O’Rourke had suggested a tandem stop with O’Rourke in front and Cook behind so with the sedan boxed in, they could slow and guide the sedan to the shoulder. They knew nothing about the occupant or occupants at this point.

[9] The officers intercepted the vehicle and, once into position, activated their emergency lights. Instead of slowing, the sedan, we now know driven by Grieves, accelerated and attempted to pass between O’Rourke’s vehicle in the passing lane and the rear of a transport truck ahead in the slow lane.

[10] Grieves failed in this manoeuvre, striking O’Rourke’s police SUV and then spinning into the median ditch where it became stuck in the grass and mud. O’Rourke stopped his SUV on the left shoulder beside the sedan which still had its engine roaring and tires spinning. O’Rourke stepped out of his vehicle, drew his firearm, and pointed it at the driver through the open window on the passenger door. O’Rourke advanced down the slope in an effort to get a better view inside the vehicle. He stubbed his foot on something in the grass and pitched forward with his gun forward being held in both hands. While moving forward he said his finger was off the trigger. In fighting to regain his balance and back his arms and gun out of the vehicle, his gun unintentionally discharged. The bullet struck Grieves in the right bicep and penetrated his chest. He ultimately died of his wound.

[11] O’Rourke is being tried on one count of manslaughter where the Crown alleges an unlawful act, that being the careless use of his firearm (s. 86(1), Criminal Code of Canada).

Analysis

[12] The primary issue to be determined by me is whether the actions of O’Rourke, in these circumstances, constitute a marked departure from those of a reasonably prudent police officer: see R. v. Porto, 2018 ONCA 291; R. v. Tabanao, 2024 ONCA 433; R. v. Javanmardi, 2019 SCC 54.

[13] The question then is whether the expert evidence of Dr. Miller is necessary for me to determine those primary issues.

[14] The decisions of the Court of Appeal in R. v. Hoggard, 2024 ONCA 613, and subsequently R. v. P.J.C., 2025 ONCA 196 (P.J.C.), both concern the threshold element of necessity in the admission of expert evidence. While both cases were sexual assault prosecutions, in each case the court determined that an expert’s opinion was not necessary for a properly instructed trier of fact to understand how those traumatic events could fracture accurate memory and recall in a victim witness.

[15] In P.J.C., at paras. 32 and 33, the court discusses the importance of the necessity requirement:

In R. v. D.D., 2000 SCC 43, [2000] 2 S.C.R. 275, at para. 47, Major J., writing for the majority, explained that, in order to meet the necessity requirement, expert opinion evidence must be necessary to enable the trier of fact either (1) to appreciate the matters in issue due to their technical nature or (2) to form a correct judgment on a matter if ordinary persons are unlikely to do so without the assistance of persons with special knowledge. The same issue had been previously addressed in R. v. Mohan, [1994] 2 S.C.R. 9, where the court cited with approval Lawton L.J.’s statement in R. v. Turner, [1975] Q.B. 834, at p. 841 to the same effect:

If on the proven facts a judge or jury can form their own conclusions without help, then the opinion of an expert is unnecessary. In such a case if it is given dressed up in scientific jargon it may make judgment more difficult.

The primary danger posed by the admission of expert evidence is, as explained by Major J. in D.D., at para. 53, that “faced with an expert’s impressive credentials and mastery of scientific jargon, jurors are more likely to abdicate their role as fact-finders and simply attorn to the opinion of the expert in their desire to reach a just result.” In judge-alone trials, “the need to draw the line properly between the role of the expert and the role of the court” remains an animating concern when determining the admissibility of expert evidence: R. v. J.-L.J., 2000 SCC 51, [2000] 2 S.C.R. 600, at para. 26; see also R. v. Sekhon, 2014 SCC 15, [2014] 1 S.C.R. 272, at para. 46.

[16] At para. 40, Rouleau J.A. explained the reason the proposed expert evidence in that case failed the necessity test:

In my view, the average person is well able to assess the credibility and reliability of witnesses such as the complainants without Dr. Haskell’s evidence. As explained by Strathy C.J.O. in G.M.C., at para. 38, people can reasonably be expected to understand that observations made in the course of traumatic events can be difficult to recall and describe accurately, and the inability to recall minor or insignificant aspects of a traumatic event does not detract from a witness’ overall reliability or credibility; these are propositions “grounded in common experience, that are familiar to every trial judge and lawyer and to lay people.”

[17] Before relying too heavily on the above appeal decisions, I have considered whether a different threshold applies in that Dr. Miller is a defence expert. While a trial judge has some discretion to relax admissibility rules when considering defence evidence, the principles and bright-line rules of admissibility must not be abandoned simply because the evidence being tendered comes from the defence. If the evidence to be relied on is clearly irrelevant or unnecessary, whether it comes from the defence or the Crown, will matter little in the final analysis: R. v. Johnson, 2019 ONCA 145 at para. 58; Modern Criminal Evidence, Emond Publications 2022, Gourlay, Jones, Makepeace, Crisp and Pomerance, Chp. 4, p. 118.

[18] As an experienced trial judge, I accept that the details of an event may be lost and accuracy imperfect when a witness to a highly stressful traumatic event is asked to describe in minute detail what took place. This exercise is made all the more difficult when pressed for explanations years later.

[19] In this case, the issue upon which I must ultimately focus is not why O’Rourke cannot remember pulling the trigger of his firearm or the dynamics of how that unintentional discharge could have happened. The issue for me is whether a reasonably prudent police officer would have drawn and pointed his firearm at all in these circumstances or whether this was a marked departure from the standard of care.

[20] For me to determine this issue, Dr. Miller’s expertise and opinion are neither necessary nor relevant.

[21] As a result, I decline to admit this defence expert evidence.

Bruce G. Thomas
Released: June 24, 2025