Introduction

In practice, I rarely tackled medical malpractice cases. I usually referred them out to specialists. However, I’ve mediated enough med-mal files to know they’re unlike anything else on the civil docket. They’re technical, emotionally loaded, and often feel pro forma at the mediation stage. I have learned some important lessons.

In Toronto’s mandatory-mediation regime, the parties show up because the Rules say so, not because anyone expects a quick handshake. Physicians are typically defended by experienced CMPA^[1]-appointed counsel. Hospitals and nurses are almost always in the mix too, because modern care is team-based. And while plaintiffs name everyone in the chain of care, the law doesn’t treat everyone the same. Different actors, different roles, and sometimes different routes to liability.

Med-mal cases frequently fail to settle at mediation because the incentives are misaligned and the issues are binary. CMPA-backed defence counsel have the budget, appetite, and mandate to fight cases that turn on expert-driven questions of standard of care and but-for causation, so unless liability is obvious they’re not paying “certainty premiums” at mediation. Physicians also carry reputational and regulatory baggage. Settlements (even no-admission ones) can feel like career scars. So they’d rather vindication at trial than a messy compromise. Hospitals worry about corporate-negligence precedents and policy fallout, which makes them allergic to deals that look like system-wide admissions.

Plaintiffs, meanwhile, face catastrophic life-care claims where valuation spreads are massive. If causation is contested, the defence prices the case near zero. If it’s proven, the numbers can jump into seven or eight figures. That all or-nothing math, combined with duelling experts, late defence reports (so mediation is often too early), and a defendant culture that manages precedent as much as exposure, means many files show up to mandatory mediation because they must—then keep marching to trial because neither side sees overlap worth buying.

This is the pattern I have observed repeated on the med-mal cases I have mediated.

Start With the Misconception—and Correct It Up Front

People often talk about “gross negligence” in medical cases, but Canadian law doesn’t require plaintiffs to prove anything “gross” at all—the civil test is ordinary negligence measured against the appropriate professional standard of care, with causation proved on a but-for basis.

That’s not a stylistic preference. It’s black-letter law. In ter Neuzen v. Korn, 1995 CanLII 72 (SCC), [1995] 3 SCR 674^[2], the Supreme Court explained that following accepted medical practice will usually satisfy the standard of care, except where the accepted practice itself is “fraught with obvious risks.” That nuance sometimes gets misread as a “gross negligence” threshold. It isn’t. It’s still ordinary negligence—reasonableness in context.

Physicians: Reasonableness, Not Perfection

Doctors are not judged by perfection or by outcomes. Lapointe v. Hôpital Le Gardeur, 1992 CanLII 119 (SCC), [1992] 1 SCR 351^[3] anchors liability in what a prudent physician would have done then, on the information and resources available at the time, not with hindsight. Experts frame that yardstick.

Ontario’s classic articulation Sylvester v. Crits et al., 1956 CanLII 29 (SCC), [1956] SCR 991^[4]—often shorthanded as Crits v. Sylvester—sets out that every practitioner must bring a reasonable degree of skill and knowledge, and specialists are held to the standard of their specialty. Courts will weigh competing expert schools of thought, but “custom” doesn’t win if it can’t be medically justified.

ter Neuzen ties those threads together. Common practice is persuasive but not conclusive. If the practice is obviously dangerous, following it won’t save a defendant. Again, ordinary negligence analysis applied to professional facts, not a special “gross” test.

Causation: From Snell to Armstrong

Proving breach isn’t enough. Plaintiffs still need “but-for” causation. In Snell v. Farrell, 1990 CanLII 70 (SCC), [1990] 2 SCR 311, the Court allowed trial judges to draw robust, common-sense inferences of causation where scientific certainty is elusive, especially when the defendant’s negligence has created an evidentiary gap. That flexibility remains central at trial and at mediation.

The Court reiterated the centrality of “but-for” and the need to connect how the breach produced the injury in Ediger v. Johnston, 2013 SCC 18 (CanLII), [2013] 2 SCR 98^[5], an obstetrics case that is useful whenever mechanism matters.

More recently, Armstrong v. Ward 2021 SCC 1 (CanLII), [2021] 1 SCR 3^[6] pushed back against over-scientizing causation. The Supreme Court confirmed that “but-for” remains the test and that trial judges may draw sensible inferences on a balanced record. That matters in mediation where defendants argue that every uncertainty kills causation.

Nurses and Hospitals: Parallel Duties, Different Roles

Nurses are judged against the standard of a competent, prudent nurse in like circumstances—again, reasonableness in the real world, not perfection. When parties challenge trial-level findings about nursing practice, appellate courts defer unless there’s a palpable and overriding error, a point rooted in Housen v. Nikolaisen 2002 SCC 33 (CanLII), [2002] 2 SCR 235^[7] which although a car accident case, is applied repeatedly in health-care negligence appeals (see, e.g., Ediger, Armstrong and Benhaim v. St‑Germain^[8]). Practically, that means you win (or lose) on the trial record (tasks, delegation, monitoring, and escalation protocols) rather than on rhetoric.

Hospitals face two avenues of exposure. First, vicarious liability for negligent employees like staff nurses. Second, institutional (corporate) negligence for systems failures—policies, staffing, supervision, equipment, triage, handoffs. Classic authorities such as Vancouver General Hospital v. Fraser 1952 CanLII 23 (SCC), [1952] 2 SCR 36^[9] and Toronto General Hospital v. Matthews 1971 CanLII 23 (SCC), [1972] SCR 435^[10]situate hospital responsibility within those frameworks, even as independent-contractor physicians and privileges complicate the picture. In mediation, that translates into a practical focus on protocols and resource allocation. Those system facts often drive settlement dynamics more than any single physician’s judgment call.

A helpful Ontario trial-level reminder comes from Latin v. Hospital for Sick Children (2007) CanLII 34 (ON S.C.)^[11]. Internal policies can inform expectations but don’t automatically set the legal standard of care. Plaintiffs still need expert evidence tying what the policy said to what reasonable nursing or institutional practice required—and to what actually happened^[12].

Recent Appellate Signals Worth Watching

Two recent Ontario Court of Appeal decisions have practical settlement implications. In Hemmings v. Peng (2024 ONCA 318)^[13], the Court scrutinized how the trial judge handled expert evidence on both breach and causation in a catastrophic obstetrics case. The takeaway for mediation is to articulate the precise standard, tie it to what the team actually did, and explain the causal chain in plain language connecting departure to harm.

In Hasan v. Trillium Health Centre (Mississauga) (2024 ONCA 586)^[14], the Court reaffirmed that Snell’s robust, pragmatic approach can fill evidentiary gaps where negligence clouds the picture. Uncertainty doesn’t always defeat causation. Sometimes it strengthens an inference when the defendant’s breach made proof harder. That’s leverage at mediation when plaintiffs need principled probability arguments, not speculation.

So Where Does “Gross Negligence” Fit—If At All?

In Canadian medical negligence, the civil standard is ordinary negligence. “Gross negligence” pops up around statutory immunities (e.g., some Good Samaritan contexts) or as rhetoric to describe a very serious departure, but it’s not a higher, separate civil test for suing doctors. If a practice is “fraught with obvious risk” (ter Neuzen), a court may find breach even where the provider followed local custom—but that’s still the ordinary negligence yardstick. For practical purposes, the path to liability runs through careful expert evidence on what reasonable care required and why the defendant’s approach fell below it, plus a causal through-line to the injury.

Mediation Reality Check

What moves these files isn’t moralizing about “gross negligence.” It’s disciplined framing.  What was the exact standard engaged. Where did the team dynamic brake. What does the chart show about timing and escalation. Did the experts credibly connect the breach to the outcome. How will the freshest appellate guidance land with a trial judge.

Physicians live or die on whether their decisions were reasonable then. Nurses face scrutiny on monitoring and escalation. Hospitals answer for systems and staffing even where an individual doctor’s judgment was defensible.

Put bluntly: the better party builds the better record.