Donna Pelrine, by her Estate Trustee James Pelrine et al. v. Chung et al., 2026 ONSC 4362 (CanLII)
Pelrine v. Chung: Divisional Court Confirms Rule 53.08 Must Be Applied Contextually
In Donna Pelrine, by her Estate Trustee James Pelrine et al. v. Chung et al., 2026 ONSC 4362, the Divisional Court confirmed that amended Rule 53.08 is stricter than its predecessor, but not a mechanical exclusionary rule for excluding expert evidence. Courts must assess the explanation for delay, prejudice, trial impact and the broader interests of justice together, especially where excluding expert evidence could prevent a party from advancing or defending the case on its merits.
The action arose from allegations that Dr. Pin Chung, Ms. Pelrine’s family physician, failed to advise her of a May 2015 CT report recommending follow-up imaging. She was not advised until November 2015. Further imaging led to hemipelvectomy surgery in April 2016, after which she died from surgical complications. As in many medical negligence cases, liability and causation depended heavily on expert evidence.
The Procedural Problem
Dr. Chung had retained experts in 2021, but his reports were not served within the Rule 53.03 deadlines. After the matter was set down for trial in December 2023, the parties failed to agree on an expert-report timetable required by Rule 53.03(2.2). At a June 2025 pre-trial, the plaintiffs confirmed the claim would proceed only against Dr. Chung. The defence then served its standard-of-care, causation and damages reports between June and August 2025, more than a year before the scheduled September 2026 jury trial.
On motion from the defence, Justice Mathai admitted the standard-of-care report but refused leave for the causation and damages reports. Justice Mathai treated Rule 53.08 as a strict conjunctive test: unless Dr. Chung first established a reasonable explanation for the delay, the court could not balance prejudice, delay or the interests of justice. Although Justice Mathai acknowledged that admission would likely not jeopardize the trial date and that the interests of justice would otherwise favour admission, he concluded that he was bound to exclude the reports.
The Divisional Court’s Analysis
The Divisional Court allowed the appeal and held that the motion Judge’s approach was too rigid. Rule 53.08 requires a reasonable explanation and absence of non-compensable prejudice or undue trial delay, but those requirements must be interpreted through Rule 1.04 and the goal of resolving proceedings justly, proportionately and on their merits. The Rule was amended to curb routine late reports, strategic delay, wasted pre-trials and avoidable adjournments—not to create disproportionate outcomes where late evidence can be managed fairly.
Regional Senior Justice Firestone, writing for the court, emphasized that a reasonable explanation need not be perfect and should not be assessed in isolation. Consistent with the Divisional Court’s earlier decision of Harris v. Grand River Hospital, 2026 ONSC 240, the full context matters: the chronology, the nature of the litigation, the importance of the evidence, the reason the deadline was missed, prejudice to both sides and the effect on the trial timetable.
Applying that framework, the Divisional Court accepted that the death of the previously retained standard-of-care expert did not itself explain the delay in the causation and damages reports. Still, the motion Judge put too much weight on whether counsel’s conduct was labelled “inadvertence” or “inattentiveness.” The proper question was whether the explanation was reasonable in all the circumstances.
Several facts supported admission: the reports were served about a year before trial; the plaintiffs had time to respond; no adjournment was required; there was no finding of tactical delay; the defence had identified its experts before the pre-trial; and both sides had failed to set an expert timetable. In the medical-malpractice context, excluding the causation and damages reports would likely have impaired Dr. Chung’s ability to defend the case on its merits. Leave was granted, with no order as to costs.
The Divisional Court’s decisions provided a few key takeaways. First, Rule 53.08 still has teeth, but the motion judge must exercise discretion. Counsel must still provide a reasonable explanation for late service. Tactical delay, deliberate disregard of deadlines or unexplained lateness may justify exclusion. But the explanation should be assessed with the full chronology, the importance of the evidence, prejudice to both sides and the trial timetable.
Prejudice remains central to the exclusion of late expert reports. The strongest leave motions will show that the opposing party can respond without disrupting the scheduled trial. The strongest opposition will identify concrete consequences: compressed preparation time, the need for new experts, lost procedural steps or a real risk to adjourn the trial date.
Expert evidence may be indispensable. In medical negligence and other complex personal injury cases, excluding an expert report may be outcome-determinative. Counsel should explain the import of how the late report relates to the issues the trier of fact must decide.
Lastly, parties should not overlook Rule 53.03(2.2). The parties’ failure to agree on an expert timetable was not determinative, but it was relevant. Counsel should document efforts to set expert deadlines early after set-down and move promptly if a deadline cannot be met.
The practical message from the Divisional Court is straightforward: amended Rule 53.08 promotes discipline in expert-report service, but not at the expense of proportionality or adjudication on the merits. A late report is not automatically saved by the absence of prejudice, but it is also not automatically excluded because counsel’s explanation is imperfect. The question is whether admission or exclusion best serves the fair, orderly and merits-based resolution of the action.