CITATION: Pelrine et al. v. Chung et al., 2026 ONSC 1601

Court File No.: CV-18-00135376-0000

DATE: March 17, 2026

ONTARIO

SUPERIOR COURT OF JUSTICE

BETWEEN:

Donna Pelrine, by her Estate Trustee James Pelrine, James Pelrine, Alexander Pelrine, Nicole Pelrine, Gloria Roberston as the Litigation Administrator for the Estate of David Robertson, Gloria Robertson, Darlene Robertson-Bootsma, Dana Robertson and Denise Robertson

Plaintiffs

– and –

Pin Chung, Peter Ferguson, James Teresi, Gregory Silverman, Thomas Forbes, Mount Sinai Hospital and Jane Nurses

Defendants

Ronald Bohm, counsel for the plaintiffs

Thomas Curry and Eli S. Lederman, counsel for Dr. Chung, Dr. Ferguson, Dr. Teresi, Dr. Silverman and Dr. Forbes

HEARD: January 8, 2026

Ruling on Motion

THE HONOURABLE JUSTICE SUNIL S. MATHAI

A. Introduction

[1] The defendant, Dr. Chung, seeks an extension to serve three expert reports pursuant to rr. 53.03(4) and 53.08(1) of the Rules of Civil Procedure, R.R.O. 1990, Reg. 194 (the "Rules"). Specifically, the defendant seeks leave to serve the expert reports of Drs. Battel, Turcotte and Hyatt.

[2] On January 30, 2026, I granted the defendant's motion with respect to Dr. Battel's report and denied the motion with respect to the remaining reports. On that date, I advised the parties that written reasons would follow. These are my reasons.

B. Background

(a) The Plaintiff's Claim

[3] The action arises out of the treatment and care of Donna Pelrine ("Donna"). Donna developed a rare form of bone cancer in 2015. The cancer was not diagnosed until late 2015 and Donna subsequently underwent hemipelvectomy surgery at Mount Sinai Hospital (the "Hospital"). Sadly, Donna died from complications arising from the surgery.

[4] The plaintiffs' statement of claim alleges negligence against six named defendants: Dr. Chung (family physician), Dr. Ferguson (orthopaedic oncology surgeon), Dr. Forbes (vascular surgeon) and Dr. Teresi and Dr. Silverman (anesthesiologists) (collectively, the "defendant physicians"), and the Hospital.

[5] Dr. Chung was Donna's family physician. With respect to Dr. Chung, the plaintiffs allege that he failed to inform Donna of the results of a CT imaging report which showed a suspicious large geode in her left hip bone. The report recommended that Donna receive a radiographic follow-up to exclude a more aggressive lesion. Dr. Chung received the report in May 2015; however, Donna was not advised of the report until November 2015.

[6] Dr. Chung provided an explanation for the delay. After Dr. Chung reviewed the CT imaging report, he placed a yellow sticky note on Donna's file. The note directed clinic staff to follow up with Donna and advise her to return to the clinic in three months or earlier if her pain persisted or worsened. The sticky note fell off the file.

[7] Donna returned to Dr. Chung in November 2015. At that time, Donna was advised of the results of the May report. Dr. Chung arranged further CT imaging which was conducted in December 2015. The December imaging report concluded that the lesion had grown and was suspected to be an aggressive cancerous lesion.

[8] After further investigations, Donna was told that the lesion was cancerous and that she required hemipelvectomy surgery.

[9] The defendant, Dr. Ferguson, performed Donna's hemipelvectomy surgery on April 18, 2016. Dr. Ferguson was assisted by the defendant, Dr. Forbes. The defendants, Drs. Teresi and Silverman, were the anesthesiologists. Further surgeries were performed due to complications arising from the hemipelvectomy surgery. Donna died on May 2, 2016.

[10] As described in greater detail below, the plaintiffs have abandoned their claim against Drs. Ferguson, Forbes, Teresi and Silverman. The action is now limited to Dr. Chung's alleged negligence.

(b) Procedural History

[11] What follows below is a summary of the procedural history of the action.

[12] The plaintiffs issued a statement of claim on April 13, 2018. On March 20, 2019, the defendant physicians served a statement of defence and crossclaim. On the same day, the Hospital delivered a statement of defence and crossclaim. Examinations for discovery were conducted between December 2–4, 2020.

[13] In January 2021, the defendant physicians sought expert assistance from Drs. Turcotte (a specialist in orthopedic oncology) and Hyatt (an expert on future income loss and dependency quantification) to provide expert opinions.

[14] The plaintiffs served Dr. Bond's expert report on February 17, 2022. Dr. Bond's report concludes that Dr. Chung breached the standard of care in arranging the second CT scan some seven months after Dr. Chung reviewed the first CT scan report.

[15] On the same day, counsel for the defendant physicians ("Trial Counsel"), inquired whether the plaintiff would be delivering additional reports to address the allegations against the other defendant physicians. In response, Mr. Bohm advised that he was awaiting a further report and would address the issue when that report was received.

[16] The plaintiffs served Dr. Clarkson's expert report on August 31, 2022. Dr. Clarkson is an orthopedic oncologist. Dr. Clarkson's report concludes that, had Donna's surgery been conducted when the lesion was smaller, then it was "more likely than not" that Donna would have survived the surgery and the perioperative period.

[17] On December 2, 2022, Trial Counsel again emailed Mr. Bohm to inquire whether the plaintiffs would be delivering reports in support of its case against the other defendant physicians. Trial Counsel also asked whether the action would be pursued against these defendants. Mr. Bohm did not respond.

[18] On August 29, 2023, Trial Counsel again emailed Mr. Bohm to inquire whether the plaintiffs intended to deliver reports with respect to the remaining defendant physicians. Again, no response was received.

[19] On December 1, 2023, the plaintiffs delivered their Trial Record. Despite r. 53.03(2.2), the parties did not communicate for the purpose of agreeing to a schedule for the service of expert reports.

[20] In early January 2024, Trial Counsel retained Dr. Stanton to provide an expert opinion with respect to whether Dr. Chung had breached the standard of care.

[21] On January 8, 2024, the plaintiffs served Dr. Katz's expert report. Dr. Katz provided an expert report on the plaintiffs' damages claim. This was the last expert report served by the plaintiffs.

[22] On February 7, 2024, Mr. Bohm wrote to Trial Counsel inquiring whether, "Dr. Chung will be delivering any reports" and whether Dr. Chung was interested in discussing an appropriate resolution. Trial Counsel did not respond.

[23] Trial Counsel was involved in a lengthy out-of-province trial which commenced in April 2024 and continued intermittently. In an affidavit filed in support of the motion, Trial Counsel deposed that they were away from the office during the trial and fell behind in this case. No further details about the out-of-province trial were included in Trial Counsel's affidavit.

[24] On June 5, 2024, Mr. Bohm sent a follow-up email to Trial Counsel. In response, Trial Counsel contacted Mr. Bohm and asked that Mr. Bohm prepare a settlement brief. Mr. Bohm delivered the brief on July 2, 2024. The brief only addressed the negligence of Dr. Chung.[^1]

[25] On September 4, 2024, Trial Counsel was advised that Dr. Stanton had passed away in August 2024. Prior to his passing, Dr. Stanton had not completed his report.

[26] In September 2024, Mr. Bohm left a voicemail message for Trial Counsel and asked whether the defendant physicians were interested in resolving the action. No response was received.

[27] On September 24, 2024, Mr. Bohm wrote to Trial Counsel requesting the courtesy of a response. Again, no response was received.

[28] On October 7, 2024, Mr. Bohm again wrote to Trial Counsel. Trial Counsel emailed Mr. Bohm on the same day and requested a telephone call. The call occurred on October 9, 2024. During the telephone call, Trial Counsel advised Mr. Bohm that Dr. Stanton had passed away without completing his report.

[29] In November 2024, the parties agreed to schedule the pre-trial conference for June 19, 2025.

[30] In February 2025, Trial Counsel requested an expert report from Dr. Battel. The report was limited to whether Dr. Chung fell below the standard of care of a family physician.

[31] The plaintiffs delivered their pre-trial brief on May 27, 2025. On June 12, 2025, the defendant physicians delivered their pre-trial brief. The pre-trial brief noted that responding expert reports were not served but identified the experts retained and summarized the content of their anticipated opinions.

[32] Casullo J. conducted the pre-trial conference with the parties on June 19, 2025. During the pre-trial, Mr. Bohm advised that the action would be dismissed as against all the defendants except for Dr. Chung. At that time, Trial Counsel requested leave to extend the deadline for serving responding reports. Casullo J. was not prepared to grant leave without a motion record. The action was placed on the September 2026 trial sittings.

[33] Trial Counsel served Dr. Battel's expert report on June 24, 2025, and Dr. Turcotte's expert report on June 27, 2025. Dr. Turcotte's report responds to Dr. Clarkson's report on causation.

[34] This motion was commenced in July 2025. There is no dispute that the defendant moved with haste to have this motion heard.

[35] Dr. Hyatt's report, which responds to Dr. Katz's report, was served on August 19, 2025.

C. Law and Analysis

(a) Governing Principles – The Amendment to r. 53.08

[36] Rule 53.08(1) was amended on March 31, 2022. Prior to the amendment, the court was required to grant leave to late serve an expert report unless doing so caused prejudice to the opposite party or caused undue delay in the conduct of the trial that could not be overcome by an adjournment or costs (see Marchand (Litigation Guardian of) v. Public General Hospital Society of Chatham (2000), 2000 CanLII 16946 (ON CA), 51 O.R. (3d) 97 (C.A.), at para. 81).

[37] With respect to prejudice, the jurisprudence established that a court was to weigh the prejudice to the opposing party against the prejudice to the proffering party. This approach was anchored on the well-established principle that relevant evidence should not be excluded on technical grounds unless the court is satisfied that the prejudice in receiving the evidence exceeds the prejudice in excluding it (see Rolley v. MacDonnell, 2018 ONSC 163, at para. 29; 2287913 Ontario Inc. v. ERSP International Enterprises Ltd., 2021 ONSC 3927, at para. 35). This principle was initially set forth in Hunter v. Ellenberger et al. (1988), 25 C.P.C. (2d) 14 (Ont. H.C.J.), at p. 16, where Barr J. held:

In my view, it should be remembered that any time a court excludes relevant evidence the court's ability to reach a just verdict is compromised. Relevant evidence should not be excluded on technical grounds, such as lack of timely delivery of a report, unless the court is satisfied that the prejudice to justice involved in receiving the evidence exceeds the prejudice to justice involved in excluding it.

(see also Auto Workers' Village (St. Catherines) Ltd. v. Blaney, McMurtry, Stapells, Friedman (1997), 14 C.P.C. (4th) 152 (Ont. C.J. Gen. Div.), at p. 8; Rolley, at para. 29; Homes of Distinction (2002) Inc. v. Adili, 2019 ONSC 7588, at para. 9; and Sean Omar Henry v. Dr. Marshall Zaitlen, 2022 ONSC 214, at para. 20).

[38] Under the old version of r. 53.08(1), prejudice and undue delay were balanced as factors in determining whether the court should displace the requirement that leave be granted (see Talluto v. Marcus, 2016 ONSC 3340, at paras. 12–14; Scott Wigmore v. Anita Myler, 2014 ONSC 6744, 123 O.R. (3d) 446, at para. 18(c)). Where the relative prejudice favoured admission, leave would be granted even where it caused an adjournment (see Stadnyk v. Dreshaj, 2019 ONSC 1184, at para. 11; Khan v. Baburie, 2021 ONSC 1683, at paras. 44–46; and Andreason v. The Corporation of the City of Thunder Bay, 2014 ONSC 580, at paras. 38–39).

[39] In Khan, at para. 45, Daley J. described the bar's treatment of the pre-amendment r. 53.08(1) as follows:

[45] The late service of export [sic] reports, contrary to the requirements of the Rules, has been a chronic and frequent issue in the timely management of the civil litigation before this court. Counsel seem to have the belief that the requirements of compliance with the Rules are mere recommendations or suggestions and that as such the breach of the Rules will really have no consequences. Counsel are sorely mistaken in that belief.

[40] The March 2022 amendment fundamentally changed how courts treat a request to extend the deadline to serve expert reports.

[41] The first reported decision that interpreted the March 2022 amendment was Edwards R.S.J.'s decision in Agha v. Munroe, 2022 ONSC 2508, 23 C.C.L.I. (6th) 118. In that decision, my learned colleague provided a helpful review of the jurisprudence under the pre-amendment rule, which he described as an "escape clause" (Agha, at para. 6), and the problems caused by the late service of expert reports. Following his review, Edwards R.S.J. held that the purpose of the new rule was to send a "very loud and clear message to all sides of the Bar, that expert reports are to be served in a timely manner and in accordance with the provisions of Rule 53.03(1) and (2)" (Agha, at para. 30).

[42] Edwards R.S.J. went on to conclude that the amendment was intended to address two significant problems associated with the late service of expert reports: (1) ineffective pre-trial conferences; and (2) routine adjournments. At paras. 31–32 of the decision, Edwards R.S.J. stated:

[31] There is a good reason to require the timely exchange of expert reports prior to the pre-trial. A pre-trial is not just an administrative step in a proceeding. It is a step that has two fundamental purposes. The first is to explore the possibility of settlement. The second important purpose is to deal with trial management issues. The comments of Stinson J. in Prabaharan, at paras. 2 and 3, are worth repeating, as in my view they are equally applicable to the new rule:

A PTC is an occasion and an opportunity for each side to develop a better understanding of their own and their opponent's case. More importantly, it is also an opportunity for each side to receive guidance and feedback from the presiding PTC judge. Based upon the contents of the PTC memos and other evidence (such as copies of expert reports) the presiding judge can discuss with a party the strengths and weaknesses of their case and assist them in re-evaluating their (and their opponent's) position on settlement.

Where one or both parties fail to follow the rules, the purpose of the PTC cannot be achieved. This is unfair to the opponent and the Court, because the time of each is wasted and the otherwise useful feedback cannot be provided. It also has the possible result of clogging the system with a case that should have settled at (or in the wake of) the PTC, but could not because inadequate information was available at the relevant time.

[32] Lawyers and litigants need to adapt to the new rule immediately. The late delivery of expert reports simply will not be rubber-stamped by the court. By shifting the onus to the party seeking the indulgence and changing the word "shall" to "may", the exercise of the court's discretion will, in my view, result in far fewer adjournments and more productive pre-trials. There will always be circumstances that are beyond the control of counsel and the parties which will fall within the definition of a "reasonable explanation" for failing to comply with the timelines for the service of expert reports. In this case, no such reasonable explanation was provided to the court.

(see also Suzanne Chiodo, "Taking Proportionality Seriously: A Countercultural Approach" (2025) 16:1 Western J. Leg. Studies 19, at pp. 26–28).

[43] Late adjournments caused by non-compliance with the Rules contribute to the culture of delay that has long plagued Ontario's civil justice system. In Forsung v. Neadow, 2023 ONSC 5873, at paras. 25–26, Muszynski J. described the "waste" caused by late adjournments and the need to strictly apply r. 53.08(1) to avoid such waste:

[25] The consequences of late adjournments of lengthy trials, particularly jury trials, reverberate through the entire justice system. Before a jury trial, court staff send out notices to prospective jurors. Parties must obtain summonses and arrange for service on their potential witnesses. The lives of prospective jurors are disrupted when they are required to attend in court. Judges, staff, and courtrooms are scheduled for the trial, and may be difficult to reschedule on short notice when a matter is adjourned. The resources consumed are enormous. Consequently, when a trial gets adjourned late and must be rescheduled, the waste is staggering.

[26] There is a crisis in the civil justice system in this province. The amendments to the Rules were meant to address the problems associated with late adjournments of trials due to non-compliance. To achieve this objective, in my view, the Rules must be strictly applied.

(see also Seo v. Francis, 2024 ONSC 4341, at para. 21; Rosato et al. v. Singh et al., 2025 ONSC 1798, at para. 27)

[44] To ensure compliance with deadlines for serving expert reports, the amendment raised the bar for extending the deadline for serving expert reports (see Agha, at para. 19; Pinchin v. Ikemoto, 2025 ONSC 3575, at paras. 41, 58; and Vaillancourt v. R.K. Mooney Insurance Brokers Ltd., 2025 ONSC 6761, at para. 47). The text of r. 53.08(1) makes this clear in three interrelated ways.

[45] First, r. 53.08(1) now provides that leave "may be granted". Judges are no longer required to grant leave.

[46] Second, the amendment requires the non-compliant party to establish a "reasonable explanation" for missing the service deadlines in rr. 53.03(1)–(3). Prior to the amendment, r. 53.08(1) did not explicitly require the non-compliant party to establish a reasonable explanation for missing the service deadlines.

[47] Third, and most importantly, the test under r. 53.08(1) is conjunctive (see Agha, at paras. 25–26; King v. Wal-Mart Canada Corp., 2025 ONSC 4947, at para. 13; Meehan et al. v. Good et al., 2025 ONSC 3347, at para. 22; Leblon Carpentry Inc. v. QH Renovation & Construction Corp., 2023 ONSC 3182, at para. 41; Rosato, at para. 25; Métis National Council Secretariat Inc. v. Chartier, 2025 ONSC 4458, at para. 37; Nykilchuk v. 2244301 Ontario Inc. et al., 2024 ONSC 5025; at para. 35; Vaillancourt, at para. 34; and Butler v. McConvey, 2025 ONSC 2485, at para. 12). Rule 53.08(1) now requires the non-compliant party to establish: (1) that there is a reasonable explanation for the failure to comply with the deadlines imposed by the Rules; and (2) that granting leave would not cause non-compensable prejudice to the opposing party or undue delay in the conduct of the trial. The conjunctive nature of the new rule is significant.

[48] As it now reads, r. 53.08(1), does not involve a balancing of reasonable explanation, prejudice and undue delay. The court only engages in the balancing of relative prejudice and undue delay if the non-compliant party has established a reasonable explanation for missing the deadlines imposed by rr. 53.03(1)–(3) (see Harris v. Grand River Hospital, 2025 ONSC 282, at para. 16; Mohamud v. Juskey, 2023 ONSC 4414, at paras. 60–61).

(b) Governing Principles – "Reasonable explanation"

[49] Generally speaking, the jurisprudence has distinguished between two categories of explanations.

[50] On one hand, this court has repeatedly found that "inattentiveness" is not a reasonable explanation (see Mohamud, at para. 58; Longo v. Westin Hotel Management, L.P., 2024 ONSC 3676, at para. 12; and Awua v. Singh Virk, 2025 ONSC 3164, at para. 22).

[51] On the other hand, this court has found that a lawyer's "inadvertence" or "mistake" can constitute a reasonable excuse, though both are on the "low end" of a reasonable explanation (see Quinn et al v. Rogers et al., 2024 ONSC 1967, at para. 25; Seo, at para. 28; Rosato, at paras. 36–37; James Bay Resources v. Mak Mera Nigeria, 2023 ONSC 2398, at paras. 62, 76; and Garcia v. Zaman, 2025 ONSC 7080, at para. 29).

[52] Given the defendant's position on this motion, I will briefly summarize the leading cases on a lawyer's "inadvertence" or "mistake".

[53] In Quinn, the defendants served their expert reports 19 days before the pre-trial. MacNeil J. granted an extension to serve late reports because defence counsel was mistaken about the date of the pre-trial conference. Given the circumstances, MacNeil J. held that counsel's mistake was a "reasonable explanation" and the defendants did not delay in serving the reports to obtain a strategic advantage (see Quinn, at paras. 25–27).[^2]

[54] In Seo, Papageorgiou J. abridged the time to serve expert reports during a pre-trial conference. The reports, while late, were served in advance of the pre-trial conference. In granting an abridgment of time, Papageorgiou J. found as follows, at para. 27:

[27] At the pretrial before me, the plaintiff's counsel indicated that the reason for the delay was turnover within his law firm with different counsel handling it from day to day as well as personal issues. I agree that this is on the low end of being a reasonable excuse, but a client should not be penalized for a lawyer's mistake particularly where there is no real prejudice to the other side. It would not assist the backlog or the civil justice system to replace a lawsuit by a plaintiff against a defendant with a lawsuit by a plaintiff against her lawyer.

[55] In Rosato, Lemay J. "reluctantly" granted leave to the late service of expert reports in circumstances where defendant's counsel did not consider that a standard of care opinion was required (Rosato, at para. 35). In arriving at this conclusion, Lemay J. held as follows, at paras. 36–37:

[36] From my perspective, it should have been obvious that negligence was alleged in this action. However, I also understand, as my colleague observed in Quinn, that mistakes can happen to us all. Counsel for the third parties argues that we cannot know what was going on in Ms. Wise's mind at the relevant time and that the explanation that is offered is not, for a good lawyer, a good explanation. I agree with that observation. However, mistakes often don't have good explanations because, to put it colloquially, a mistake is when "someone screwed up".

[37] As a result, I accept the explanation in this case as being a reasonable excuse. However, I would note three points in that regard. First, like my colleagues, I view the explanation as being at the "low end" of reasonable. Second, I would not want to be taken as making a finding that, any time a solicitor claims inadvertence, the Court will accept the explanation. While not before me, I would note that a case like this one, but where Ms. Wise had drafted the pleading and been counsel of record from the outset rather than stepping in halfway through might well have turned out differently. In short, this is a "close call".

[56] The distinction between "inattentiveness" and "inadvertence" is not always clear. Both terms can cover a wide range of purported "reasonable explanations". Sometimes, the distinction can be used by parties to obscure what the court should remain focused on — whether the proffered excuse for missing the deadline is reasonable in the circumstances of the case. In Vaillancourt, Charney J. described this issue as follows:

[47] Moreover, the term "inadvertence" is a broad, indeterminate term that could capture virtually any negligent conduct, from a brief delay to prolonged neglect. "Inadvertence" simply means that the failure was not "deliberate". It seldom is. The Plaintiff's affidavit in support of its position on this motion does not describe what the inadvertence was or explain how or why it occurred, other than the "turnover of staff". The Plaintiff should not be able to avoid the consequence of his failure to comply with the timelines simply by saying "inadvertence".

(see also Mohamud, at paras. 55–56)

[57] Ultimately, whether the non-compliant party has established a reasonable explanation for missing the deadline is case-specific. While categories like "inattentiveness" or "inadvertence" are of assistance, I find that the central focus should be whether the proffered explanation is reasonable based on the record before the court and with regard to the purpose of the rule.

(c) Governing Principles – r. 53.03(4)

[58] Notably, when r. 53.08(1) was amended, the Attorney General for Ontario chose not to amend r. 53.03(4) to cross-reference r. 53.08(1). Rule 53.03(4) reads as follows:

Extension or Abridgment of Time

(4) The time provided for service of a report or supplementary report under this rule may be extended or abridged,

(a) by the judge or associate judge at the pre-trial conference or at any conference under Rule 77;

(b) by the court, on motion; or

(c) on the written consent of the parties, except that the parties may not consent to an extension that would affect the scheduled trial date.

[59] The parties agree that the test as set out in r. 53.08(1) should apply to the defendant's request. The parties' position is consistent with several rulings from this court which have held that the test in r. 53.08(1) applies to a motion to extend or abridge the time to serve expert reports under r. 53.03(4) (see Van Belois v. Bartholomew, 2023 ONSC 5799, at para. 14; Vaillancourt, at para. 35; Rosato, at paras. 25–26; Quinn, at para. 16; Okafor v. Wilson, 2025 ONSC 6972, at paras. 14–16; and Mohamud, at paras. 22–26).

[60] Both rules 53.03(4) and 53.08(1) must be interpreted in light of r. 1.04, which requires that the rules, "be liberally construed to secure the just, most expeditious and least expensive determination of every civil proceeding on its merits". That said, r. 1.04 does not displace the clear text of r. 53.08(1), which imposes a conjunctive test. Once a reasonable explanation has been established, then the court must go on to consider whether the interests of justice favour allowing the evidence and whether the opposing parties will be taken by surprise by the admission of the evidence (see Saint-Fort v. Ashcroft Homes – Eastboro Inc., 2023 ONSC 1981, at para. 21; Premform Limited v. Heights Rental Construction Inc., 2023 ONSC 955, at paras. 34–35). Put another way, in the absence of a reasonable explanation, the interests of justice will not favour the admission of the evidence.

D. Application of Legal Principles

[61] Mr. Curry, who was not involved in this action until this motion, argues that there are two reasonable explanations for the delay. First, the unexpected death of Dr. Stanton. Second, Trial Counsel's "inadvertent" errors.

(a) Dr. Stanton's death

[62] I accept that Dr. Stanton's untimely passing is a reasonable explanation for the delay in serving Dr. Battel's report.

[63] The facts of this case are similar, though not identical to the case of Cepecawer v. McKevitt et al., 2023 ONSC 219. In Cepecawer, Varpio J. granted the plaintiff's motion to abridge the time to serve an expert report in circumstances where an unexpected event required counsel to retain a new expert.

[64] In that case, a trial was adjourned for thirteen months because the plaintiff's expert was unable to testify at trial. Approximately six months after the adjournment, the plaintiff advised that their expert had retired, and they would deliver a new expert report from an alternative expert. That second report was served a month later. In granting leave, Varpio J. held that the unexpected unavailability of the expert constituted a reasonable explanation for the late delivery of the second report (see Cepecawer, at para. 15).

[65] The common feature between Cepecawer and this case is an unexpected event that is out of the control of the non-compliant party and causes the report to be served late. As noted above, Trial Counsel retained Dr. Stanton in February 2024, just two months after the trial record was delivered. Trial Counsel learned of Dr. Stanton's death in early September 2024 and took steps to identify and retain an alternative expert on the standard of care. This was done by February 2025, and Dr. Battel's report was served on July 24, 2025.

[66] The above timeline suggests that Trial Counsel did not move with haste to retain Dr. Battel. Similarly, it does not appear that Dr. Battel moved with haste to complete the report. The plaintiffs rely on these delays to argue that Dr. Stanton's unexpected death is not a reasonable explanation for failing to adhere to the deadlines. I accept that the record before me does not fully explain these delays. Nevertheless, I find that Dr. Stanton's passing is a reasonable explanation for the delay in serving Dr. Battel's report. But for Dr. Stanton's death, a family physician standard of care report would undoubtedly have been served in advance of the deadlines imposed by the Rules.

[67] Importantly, neither Dr. Turcotte[^3] nor Dr. Hyatt's[^4] reports were premised on Dr. Battel's standard of care opinion. As such, the late service of Dr. Battel's report, which is partly explained by Dr. Stanton's passing, did not have a "domino effect" on the other reports. Dr. Stanton's passing is not a reasonable explanation for missing the deadlines with respect to Drs. Turcotte and Hyatt.

(b) Trial Counsel's "errors in judgment"

[68] At paragraph 42 of his factum, the defendant identifies the following "errors in judgment" that caused the service deadline to be missed:

(a) Trial Counsel made a "judgment call" to wait to know if the action would proceed against all the defendant physicians before delivering the responding expert reports;

(b) Trial Counsel should have involved his colleagues to assist with the action while he was out of the province while handling another trial;

(c) Trial Counsel ought to have raised the issue of scheduling delivery of the responding reports with plaintiff's counsel in advance of the deadline under the Rules; and

(d) Trial Counsel should have requested a later date for the pre-trial conference.

[69] Mr. Curry argues that Trial Counsel did not delay in serving the expert reports to acquire a tactical advantage. I agree.

[70] Mr. Curry also argues that Trial Counsel's actions reflect mistakes. Again, I agree.

[71] Mr. Curry goes on to assert that a reasonable explanation is established because Trial Counsel explained why he missed the deadlines. I disagree.

[72] Labelling Trial Counsel's actions as "mistakes" does not make an "explanation" a "reasonable explanation". Not all "mistakes" are "reasonable explanations". What constitutes a reasonable explanation will depend on the facts of the case and the purposes of r. 53.08(1).

[73] When a party serves an expert report late but still serves it well in advance of the pre-trial, a reasonable explanation for missing a deadline may include honest mistakes. In that scenario, the mischief that r. 53.08 is designed to address is not engaged — the parties can still engage in settlement discussions at the pre-trial conference, and an adjournment of the trial may not be necessary. Where an effective pre-trial settlement can occur, missing the deadline is merely a technical breach of the Rules. Accordingly, what may be considered a "reasonable explanation" will be more permissive and can include explanations that fall at the "low end" of the reasonable explanation spectrum (see Quinn, at paras. 8, 11, and 25; Seo, at para. 27; and Vaillancourt, at paras. 52–53).

[74] When expert reports are served after a pre-trial conference, the court must carefully scrutinize the explanation on offer because the failure to adhere to the deadline under the Rules is more than a technical breach. This point was emphasised by Lemay J. at para. 38 of Rosato:

[38] Finally, in the Defendants' factum, they rely on the decision in 1196158 Ontario Inc. v. 6374013 Canada Limited, 2012 ONSC 544 for the proposition that the Court will (at para. 19) "strive to avoid a purely formalistic and mechanical application of timelines that would penalize parties for technical non-compliance…". The case before me is not an incident of "technical non-compliance". The failure to prepare expert reports in advance of the pre-trial denies the parties, and particularly the other side, from the benefit of a confidential and candid discussion of the merits of their case with a judicial officer. This is a substantive right that aids the parties in better understanding the merits of their case and the strategy that should be adopted to advance it. It is no answer to this concern to say that a second pre-trial could be scheduled. That would just encourage further delays. [Emphasis in original].

[75] Where the non-compliant party serves an expert report after the pre-trial conference, it is possible that an honest mistake or inadvertence may still amount to a reasonable explanation, as in Rosato and Garcia. However, in circumstances where an expert report is served after the pre-trial, the court will have less tolerance for such mistakes (see Rosato, at paras. 29, 38).

[76] In this case, all the defendant's expert reports were served after the pre-trial conference. As a consequence, both parties have been denied an effective pre-trial conference and I am required to carefully scrutinize the explanations asserted to determine if they are, in fact, reasonable. Having conducted this exercise, I find that the "mistakes" identified above, taken individually or together, do not establish a reasonable explanation for missing the deadline for serving Dr. Turcotte's and Dr. Hyatt's responding reports.

(i) Waiting on the plaintiffs – the "judgment call"

[77] I accept Trial Counsel's evidence that they made a "judgment call" to wait to know if the action would proceed against all the defendant physicians before delivering the responding expert reports. I also accept that this was a mistake. I do not, however, accept that this is a reasonable explanation in the circumstances of this case. I arrive at this conclusion for three reasons.

[78] First, the plaintiff was under no obligation to dismiss the action against the remaining physicians at any time. As a result, it was not reasonable for Trial Counsel to miss the deadlines with the hope that plaintiffs' counsel would narrow the claim. Trial Counsel had all the plaintiffs' reports since January 2024 and should have responded to those reports instead of waiting to determine whether further reports from the plaintiffs were coming.

[79] At the time the pre-trial was scheduled, Trial Counsel knew the following: (a) that the plaintiffs' expert reports on standard of care and causation were limited to the theory that Dr. Chung was negligent; (b) that the plaintiffs' damages report was based solely on Dr. Clarkson's causation report; and (c) that the remaining physicians were still defendants in the action.

[80] Equipped with this knowledge, Trial Counsel should have served responding expert reports in compliance with r. 53.03(2). If the plaintiffs subsequently served expert reports in relation to the other physician defendants, then there is little doubt that the defendant would have been granted leave to serve late responding reports. In this context, Trial Counsel's intentional choice to wait to serve expert reports is not a reasonable explanation for missing the service deadline.

[81] Second, it should have been clear that the plaintiffs' claim was only focused on Dr. Chung. I come to this conclusion because:

(a) Dr. Bond's expert report only addressed Dr. Chung's alleged breach of the standard of care. This report was served on February 17, 2022;

(b) Dr. Clarkson's expert report only addressed whether the delay caused by Dr. Chung's alleged breach of the standard of care caused Donna's death. This report was served on August 31, 2022;

(c) Mr. Bohm delivered a settlement brief to Trial Counsel on July 2, 2024. The brief only addressed Dr. Chung's negligence;

(d) The pre-trial conference was scheduled in November 2024. At that time, the plaintiffs had not served any further expert reports; and

(e) The Rules required the plaintiff to serve any expert reports 90 days before the pre-trial conference. No further expert reports were served.

[82] There was a time where Trial Counsel's "judgment call" was reasonable. That time passed after receiving the plaintiffs' settlement brief and realizing that the plaintiffs' claim was limited to Dr. Chung. The settlement brief was served approximately 4 months before the pre-trial conference was scheduled and approximately 11 months before the actual pre-trial. There was more than enough time for Trial Counsel to obtain the responding reports. Continuing to wait after this date was not reasonable.

[83] Finally, even if I were to accept that the "judgment call" was a reasonable explanation, the defendant has not established that the "judgment call" was the reason for missing the service date.

[84] At the very latest, Trial Counsel should have taken steps to obtain an expert report from Drs. Turcotte and Hyatt after the plaintiffs' 90-day deadline past. On the record before me, there is no evidence that this was done. Trial Counsel's pre-trial brief, served June 12, 2025, identified Drs. Turcotte and Hyatt and described their anticipated opinions. While the record establishes that Drs. Turcotte and Hyatt were retained in January 2021, I have no evidence that establishes when these experts were asked to prepare the reports at issue and why the reports could not have been obtained prior to the deadline imposed by r. 53.03(2) or prior to the pre-trial conference. In the absence of such evidence, the defendant has not met its burden to establish that the "judgment call" was the reason Trial Counsel failed to meet the service deadline, or even serve the reports prior to the pre-trial conference.

[85] The defendant relies on Lemay J.'s decision in Rosato to argue that Trial Counsel's "judgment call" is a reasonable explanation. The defendant's reliance on Rosato is misplaced. In Rosato, Lemay J. accepted counsel's mistake as a reasonable explanation because counsel had taken carriage of the file "midstream". Unlike the situation in Rosato, Trial Counsel had carriage of this action from at least February 2022. Trial Counsel reviewed the settlement brief and knew that the plaintiffs' claim was limited to Dr. Chung's alleged negligence. Having "lived" the file, Trial Counsel does not get the same benefit of the doubt that Lemay J. extended to counsel in Rosato.

(ii) Engaging colleagues

[86] I agree that Trial Counsel waited too long to engage his colleagues while he was out of the province on another trial and that this was a mistake. However, I do not accept that this mistake is a reasonable explanation. I come to this conclusion for two reasons.

[87] First, Trial Counsel had co-counsel on this matter. Co-counsel is a senior partner at the firm. To be fair, the senior partner was not copied on the correspondence filed in the motion records and it is not clear how involved they were on the file. That said, the defendant has the burden of establishing a reasonable explanation for missing the deadline imposed by the Rules. To offer this mistake as a reasonable explanation, I would have expected an affidavit from the senior partner stating why they were not able to assist when Trial Counsel was out of the province.

[88] In Longo, Edwards R.S.J. rejected the argument that junior counsel's inattentiveness to a file was a reasonable explanation. In doing so, Edwards R.S.J., at para. 11, noted that supervisory counsel had a responsibility to ensure that junior counsel was fulfilling their responsibilities:

[11] The so-called reasonable explanation that was argued by Ms. Gaw on behalf of her client, was to suggest that junior counsel had failed in his responsibilities. Junior counsel has a responsibility to ensure that a file is being properly handled on a day-to-day basis. This includes timely responses to emails and phone calls from opposing counsel. However, to lay the blame at the feet of Junior counsel or a law clerk does not meet the definition of a "reasonable explanation". With respect I suggest that supervising counsel also have a responsibility to ensure that junior counsel is fulfilling his or her responsibilities to the client and to the Court. In this case, that does not appear to have occurred.

[89] The same rationale applies in this case. While co-counsel was not supervising Trial Counsel, there is no evidence before me that establishes that co-counsel could not have assisted in managing this matter while Trial Counsel was on the out-of-province trial. Both counsel of record had a responsibility to ensure that the deadlines for serving the defendants' expert reports were met. On the record before me, it is clear that Trial Counsel failed in this responsibility, and it is unclear why co-counsel did not ensure that the deadlines were met.

[90] Second, I do not accept that Trial Counsel's "error in judgment" was not seeking assistance from colleagues. The defendants' characterization of this "error in judgment" is an attempt to transform an explanation that would normally be described as "inattentiveness" into "inadvertence", the latter of which is more readily found to be a "reasonable explanation".

[91] It is helpful to recite the explanation provided by Trial Counsel in his affidavit:

[46] My trial commitments meant I did not have time to address this in the way I would normally have done. With other colleagues, I have been counsel in a lengthy trial in Halifax, Nova Scotia that I have been working to prepare for some time. The trial itself began in April 2024 and has continued intermittently since that time. That case has been the subject of mid-trial adjournments and proceedings that meant I was not at my office when I expected to be. As a result, I fell behind in this case, which I regret. I recognize that I ought to have asked for the assistance of colleagues in advancing these issues during that time and I regret that I did not seek help.

[92] Trial Counsel's evidence demonstrates a lack of attention to this action. It further establishes that Trial Counsel intentionally chose to give priority to his out-of-province trial to the detriment of defending this action. Trial Counsel's deliberate choice is not a reasonable explanation for missing the deadline imposed by the Rules. Describing these choices as inadvertent mistakes (i.e., not asking for help) does not make the choices reasonable.

[93] The defendant's argument strikes me as a good example of how the labels of "inadvertence" or "inattentiveness" can obscure the real question that the court needs to answer — whether the explanation on offer is a reasonable explanation. Acceding to the defendants' argument would render the "reasonable explanation" element of the r. 53.08 test meaningless. It would mean that counsel could transform lengthy periods of inactivity into a reasonable explanation by claiming that it was a mistake not to seek the assistance of colleagues when failing to meet responsibilities on a file. Such an approach would effectively neuter the salutary effects of r. 53.08(1) and must be rejected.

[94] In oral argument, I asked Mr. Curry whether Trial Counsel's evidence (as deposed in para. 46 of his affidavit) was a concession that he was inattentive to the file. In response, Mr. Curry argued that "inattention without explanation is different … different quality of conduct than inattention that is explained by inadvertence". Respectfully, I cannot accept this position. Inattentiveness to a file, absent truly exceptional circumstances, cannot morph into inadvertence because of counsel's practice demands. If this were a correct statement of the law, then there is little doubt that decisions like Longo and Mohamud would have been decided differently. If I were to accept this argument, then r. 53.08(1) would effectively revert back to being an "escape clause". Such an approach must be rejected.

(iii) Failing to agree on a schedule for delivery of expert reports and scheduling the pre-trial

[95] I do not accept that failing to agree to a schedule for the delivery of expert reports or "mistakenly" agreeing to the June 2025 pre-trial conference date is a reasonable explanation for missing the service deadlines.

[96] With respect to r. 53.03(2.2), the defendant's argument makes two assumptions. First, Mr. Bohm would have agreed to a schedule that is different from the timelines established by rr. 53.03(1)–(3). Second, that Mr. Bohm would have abandoned the claim against the remaining defendant physicians prior to the pre-trial. Both assumptions are speculative and appear to be inconsistent with the record before me. Putting aside the speculative nature of these assumptions, I also reject the suggestion that intentionally failing to adhere to a mandatory rule (i.e., r. 53.03(2.2)) can be a reasonable explanation for failing to adhere to another mandatory rule (i.e., r. 53.03(2)).

[97] Finally, I do not accept that agreeing to a June 2025 pre-trial is a reasonable explanation for missing the service deadline. The same argument was rejected by Boswell J. in Mohamud, at paras. 53–54:

[53] The explanation on offer is that the defendants' clerk agreed to fix a pre-trial date without first consulting with counsel who had carriage of the file. The court is invited to draw the inference that had such a consultation occurred, counsel would have insisted on a pre-trial date farther down the road, so that defence experts' reports could be obtained and served in compliance with the Rules. At the very least, in consideration for agreeing to an earlier pre-trial date, defence counsel may have been in a position to negotiate concessions regarding the attendance at defence medical examinations and the late-filing of any reports generated as a result of those examinations.

[54] The explanation is, in my view, weak. The case went through a failed mediation and was then set down for trial. The next step in the process is a pre-trial conference. Defence counsel were aware – or ought to have been aware – that the plaintiff's counsel was beginning to seek pre-trial dates as early as April 2022. That should have triggered the realization that if defence expert reports were going to be sought, the time was nigh to go about organizing them. For reasons best known to defence counsel, they did nothing.

[98] The same reasoning applies to this case. The defendant should have know in July 2024 that the plaintiffs' claim was limited to Dr. Chung's alleged negligence. This was nearly 4 months before the pre-trial was scheduled and nearly 11 months before the pre-trial conference. Having rejected the "judgment call" explanation, I cannot accept that not scheduling a later date for the pre-trial is a reasonable explanation for missing the service deadline.

(c) Prejudice and undue delay in the trial

[99] The plaintiffs argue that they have suffered prejudice because they have been denied an effective pre-trial conference. As noted above, the importance of a pre-trial conference cannot be overstated. The timelines for serving expert reports were designed, in part, to ensure that the parties can receive judicial guidance and mediation during the pre-trial conference. This cannot be done in the absence of expert reports.

[100] That said, this type of prejudice alone is not sufficient to warrant denying leave. If it was, then the Rules would not permit leave to be granted in circumstances where expert reports were delivered after the pre-trial. The Rules are not so rigid.

[101] As explained above, where a non-compliant party seeks to serve expert reports after a pre-trial conference (or just before), the court will carefully scrutinize the explanation on offer. That approach is consistent with the purpose of r. 53.08(1) and is preferable to a "bright line" rule where non-compensable prejudice is always found when an expert report is filed after (or just before) a pre-trial conference.

[102] The plaintiffs have had Dr. Battel's report since June 25, 2025. The trial does not commence until September 2026. My ruling on the motion was provided to the parties on January 30, 2026. There was and continues to be ample opportunity for the plaintiffs to request a reply report from Dr. Bond. There is no evidence that suggests the contrary. Granting the defendant an extension with respect to Dr. Battel's report will not cause any non-compensable prejudice to the plaintiffs, nor will it delay the start of the trial.

[103] On the other side of the equation, Dr. Chung will suffer serious prejudice if he is not granted an extension with respect to Dr. Battel's report. I grant the defendant's motion with respect to Dr. Battel's report.

[104] Given my findings on the "reasonable explanation" stage of the r. 53.08(1) test, I am not strictly required to evaluate prejudice and undue delay with respect to the remaining reports. However, as a matter of completeness, I will address the plaintiffs' arguments on this issue.

[105] In oral submissions, Mr. Bohm suggested that the plaintiffs might need to retain a new expert to respond to Dr. Turcotte's report and that this could delay the commencement of the trial. The plaintiffs did not file any evidence in support of this argument. While the burden for leave is squarely on the defendant, the plaintiffs have a persuasive burden to lead evidence on this issue if they intend to argue that the defendant has not satisfied r. 53.08(1)(b). For example, the plaintiffs could have led evidence from Dr. Clarkson that he was not qualified to reply to Dr. Turcotte's report. No such evidence is before me. In the absence of such evidence, the plaintiffs' argument is speculative.

[106] I also reject the plaintiffs' submission that Dr. Clarkson's report caught them by surprise. The defendant physicians' statement of defence and crossclaim contested causation, and no official admission of causation was given. The plaintiffs were certainly surprised that an expert report on causation was served so late. However, in the absence of a formal admission, the plaintiffs should not have been surprised that a causation report was obtained.

[107] As a result, had I found that a reasonable explanation was provided with respect to Dr. Turcotte's and Dr. Hyatt's reports, I would have found that the interests of justice favour the admission of the reports.

E. Conclusion

[108] I recognize that my ruling appears harsh. The last of the defendant's reports were served just over a year before the trial is scheduled to commence. Even if all three reports were admitted, there is little risk that the trial would be adjourned. In the circumstances, one could reasonably ask why the defendant is being denied an extension to serve his causation and damages reports?

[109] The answer to this question can be found in the text of r. 53.08. Both the plain text of the rule and the weight of the authority from this court[^5] confirms that the test is conjunctive. If the test required a balancing of a reasonable explanation, prejudice and undue delay, then my ruling would have been different.

[110] There is no doubt that applying the conjunctive test will lead to situations where a client is burdened by the "sins of counsel". This will occur in every case where counsel cannot establish a reasonable explanation for missing the service deadline. This, however, is not a "bug" of r. 53.08(1), it is an intentional feature.

[111] The previous version of the rule was treated as an "escape clause". It did not encourage compliance with the deadlines set forth in the Rules. The overuse of this "escape clause" contributed to the crisis in the civil justice system. In elevating the requirements for seeking an indulgence, the amendment was intended to send a message: missing deadlines has consequences for the civil justice system and will not be tolerated absent satisfaction of a stringent test. Where no reasonable explanation is provided, then r. 53.08(1) ensures that the "sins of counsel" are not occasioned on the civil justice system.

[112] I strongly urge the parties to come to an agreement on costs. If an agreement cannot be reached, then the plaintiffs will deliver written submissions on costs (no more than 3 pages, not including a costs outline) on or before April 10, 2026. The defendant will deliver responding submissions (no more than 3 pages, not including a costs outline) on or before May 1, 2026.

[113] Finally, I thank counsel for their written and oral submissions. Both forms of advocacy were exceptional and were of great assistance to the court.

The Honourable Justice Sunil S. Mathai

Released: March 17, 2026

[^1]: Mr. Pelrine swore an affidavit in response to the motion. In that affidavit, Mr. Pelrine deposed that the brief "refers only to negligence of Dr. Chung, and no one else". In oral argument, Mr. Curry advised that the defendant did not take issue with the plaintiffs' evidence regarding settlement as it did not reveal settlement positions.

[^2]: In Quinn, MacNeil J. primarily relied on decisions applying the old rule. Given the changes to r. 53.08(1), I have doubts that the pre-amendment decisions are of any utility in evaluating whether leave should be granted under the current rule (see Vaillancourt, at para. 42).

[^3]: Dr. Turcotte was asked to answer a number of questions that were all premised on Donna having surgery in December 2015. Dr. Turcotte was not provided with a copy of Dr. Battel's report.

[^4]: Dr. Hyatt's report relies on Dr. Turcotte's opinion on Donna's life expectancy. Dr. Hyatt was not provided with a copy of Dr. Battel's report.

[^5]: There is at least one case which has found that r. 53.08 requires a balancing of reasonable explanation, prejudice and undue delay. In James Bay, Papageorgiou J., at para. 62, held that, "[c]ounsel for the Defendants argued that inadvertence could not constitute a reasonable explanation. I agree that the explanation is on the very low end of what is reasonable. However, in my view, the Court should balance all of the factors in coming to a just result, and I will do so at the conclusion of these reasons taking into account the quality of the explanation given."