“Legal Causation” Swept into the Dustbin in Favour of “Remoteness”

By Megan Chan

In Hemmings v. Padmore, 2026 SCC 34, the Supreme Court of Canada clarified and reaffirmed the principles relevant to the factual causation and remoteness inquiries, for claims in medical negligence, as well as negligence cases more broadly.

Hemmings is a medical negligence case arising from an unfortunate cardiac arrest following anesthetic complications during an emergency caesarian section that resulted in severe and permanent brain damage for Ms. Hemmings. Ms. Hemmings (by Litigation Guardian) and her family commenced an action against a number of her healthcare providers, including multiple obstetricians involved at various points of her pregnancy, the on-duty anesthesiologist at her delivery, as well as the Hospital and nurses involved in her care.

Two appeals were before the Supreme Court of Canada, which were brought by:

1. the Hemmings (the plaintiffs), who appealed the Court of Appeal’s dismissal of the actions against the defendants, Scarborough Health Network (the hospital) and Dr. Padmore (obstetrician), and
2. Dr. Jamensky (one of the defendants; obstetrician), who appealed the Court of Appeal’s decision to uphold the trial judge’s findings regarding factual causation and the sufficiency of the trial judge’s reasons.

Three sets of reasons were delivered, with various Justices dissenting in part on various issues. Ultimately, both appeals were dismissed. 

Although much could be discussed about the Court’s reasons for dismissing the appeals (and the various Justices’ opinions on why they would allow certain parts of the appeals), this blog post will focus on the Court’s reasons pertaining to the principles of causation, and more specifically, the analysis of factual causation and remoteness in the modern law of negligence.

The Court emphasized that factual causation and remoteness are analytically distinct and that they serve two different functions in the negligence analysis. Factual causation is a strictly causal question, whereas remoteness is a normative inquiry into whether there is a sufficient connection between the defendant’s wrongful conduct and the plaintiff’s injuries such that the defendant should be liable.

Factual Causation

The “but for” test

The Court confirmed that the “but for” test from Clements v. Clements, 2012 SCC 32, remains the test for factual causation. The plaintiff must show on a balance of probabilities that “but for” the defendant’s negligent act, the injury would not have occurred.

The defendant’s conduct must be a necessary cause of the plaintiff’s injury, but not necessarily the sole cause. Multiple actors can be jointly and severally liable, where the plaintiff’s injuries are the result of multiple negligent acts by the multiple actors respectively, if each negligent act is a necessary cause of the injury.

Where it is impossible to determine which of a number of negligent acts by multiple actors in fact caused the injury, but it is established that one or more of them did in fact cause it, a plaintiff may recover without showing “but for” causation. Instead, the plaintiff would need to show a “material contribution to risk of injury”.

The “but for” test should be applied in a robust, common-sense fashion. The court must consider all the evidence before it (factual, statistical, and that which the judge is entitled to presume).

A defendant may rebut an inference of causation by introducing evidence demonstrating that the injury would have occurred regardless of their negligent conduct. In such circumstances, the burden to prove factual causation remains with the plaintiff.

When is an explicit counterfactual analysis required?

A finding of factual causation necessarily entails the exclusion of the counterfactual where the plaintiff’s injuries occur regardless of the defendant’s breach of the standard of care.

Whether a judge must engage in an explicit counterfactual analysis or whether a common-sense inference of factual causation may be drawn depends on the complexity of the circumstances of the action.

If the action is relatively simple (such as where the action involves a single plaintiff and defendant, or where the defendant’s conduct is the sole physical cause of the full extent of the plaintiff’s injuries), the trial judge may not need to explicitly explore and reject the counterfactual in their reasons. An inference that the trial judge considered and rejected the counterfactual can be made from a finding of factual causation.

If the action is more complex (such as where there are multiple defendants, a significant amount of time has elapsed between the defendant’s negligent conduct and the plaintiff’s injury, each party has advanced competing theories of causation supported by the evidence, or expert evidence about causation is equivocal or contradictory), then a trial judge may be required to engage in an explicit counterfactual analysis of whether, if a given defendant’s conduct had not fallen below the standard of care, the harm to the plaintiff would nonetheless have occurred.

What is a counterfactual analysis?

In considering the counterfactual, the court determines the factual matrix leading to the plaintiff’s injuries, then omits the defendant’s negligent conduct and asks whether the plaintiff would have still suffered the same injury.

If after considering the counterfactual, the court concludes that the damage would have happened just the same, breach or no breach of the standard of care, then the breach is not the factual cause of the damage.

Remoteness

A negligent defendant can only be liable for those consequences that they could have reasonably foreseen at the time of their breach of the standard of care and from their vantage point. Professional defendants are assessed based on the skill and knowledge of the reasonable practitioner in their position at the time.

The Court unanimously articulated a preference for the term “remoteness” to describe (and replace) the terms “legal causation”, “proximate cause”, “proximity”, and “cause-in-law”.

Corrective justice and correlativity

The remoteness analysis focuses on whether the injury is too far removed from the defendant’s wrongful conduct to justify imposing liability.

From the corrective justice perspective, remoteness puts limits on the scope or ambit of the risk created by a defendant’s negligent conduct that results in liability. A defendant will only be liable to a plaintiff where the parties are linked in a correlative relationship of doer and sufferer of the same injustice.

Remoteness is ultimately a context-specific inquiry that is guided by the body of case law. Recurring factual situations like thin-skulled plaintiffs, rescuers, and intervening acts remain important in providing guidance on how remoteness principles apply in common patterns of harm.

Remoteness is not a policy lever

The Court confirmed that remoteness does not operate as a residual policy lever to be applied whenever liability would offend broad notions of fairness or public policy. The scope of liability cannot be determined categorically based on general policy considerations that attach to a profession or a type of activity.

Reasonable foreseeability versus a risk-based approach

Interestingly, the Justices frame the remoteness analysis in two “functionally equivalent” approaches.

1. Reasonable foreseeability

Justices Rowe and O’Bonsawin reiterated a more traditional framing of the approach to the remoteness analysis. Remoteness is an inquiry into whether the injury suffered by the plaintiff was a reasonably foreseeable consequence of the defendant’s negligent conduct.

For the plaintiff’s injury to be reasonably foreseeable, there must have been a real risk or probability, one greater than a mere possibility, that that type of injury could occur. The risk must be sufficient in that a reasonable person in the defendant’s position would not brush it off as far-fetched and would have taken reasonable precautions to prevent it. The type of accident or incident needs to haven been foreseeable, but its particulars, as in the physical sequence of cause and effect that finally brought about the plaintiff’s injuries, do not.

What is a “real risk” of harm?

Justices Rowe and O’Bonsawin clarified that the inquiry into “real risk” is not merely a public policy exercise grounded in the judge’s view of what is fair in the abstract. Determining what is or is not a “real risk” of harm requires the court to address whether that risk is one that a reasonable person ought to have foreseen, and therefore taken reasonable precautions to prevent. Put differently (as Justice Martin did), conduct is not negligent unless it creates an objectively unreasonable risk of harm.

In assessing risk for the purposes of the reasonable foreseeability analysis, both the likelihood and the severity (which collectively make up the magnitude) of the harm should be considered.

Remoteness versus the duty of care analysis

Both remoteness and the duty of care have a limiting purpose and confine liability in negligence to injuries that fall within the subset of possible harms arising from risks that were unreasonable, and therefore normatively wrong, created by the defendant.

The duty of care analysis asks whether there is a sufficient link between the defendant’s wrongful conduct and the type of injury. Whereas the remoteness analysis asks whether there is a sufficient link between the defendant’s wrongful conduct and the plaintiff’s particular injury.

Reasonable foreseeability is analyzed in both the duty of care and remoteness analyses:

• Reasonable foreseeability in the duty of care analysis is focused on the type of harm and the class of plaintiff, with the analysis starting by considering established categories of relationships where a duty of care has been recognized, before moving to the Anns/Cooper test if no existing category is applicable.

• Reasonable foreseeability in the remoteness analysis is focused on whether the actual injury suffered by the actual plaintiff was reasonably foreseeable to the defendant.

Justice Martin added that maintaining the duty of care and remoteness as distinct inquiries allows courts to describe duties of care at a high level of generality (which provide a large measure of certainty) while ensuring that liability is not imposed where the plaintiff’s injuries fall outside the scope of the unreasonable risks created by the defendant’s conduct.

2. A risk-based approach

Justice Martin articulated a functionally equivalent, risk-based approach to the remoteness analysis, which asks instead whether the injuries suffered by the plaintiff fell within the scope of those risks that it was unreasonable (and therefore negligent) for the defendant to have created.

Justice Martin emphasized that the plaintiff’s injury is necessarily too remote if the possibility of that injury occurring did not form part of the basis for holding that the defendant’s conduct breached the standard of care, even if that conduct was a factual case of the injury.

Her Honour explained that one of the challenges faced when the remoteness analysis is framed as foreseeability of injury is identifying the level of generality at which to describe the plaintiff’s injury. A broader description expands the range of foreseeable injuries while a narrower one restricts it. Therefore, the chosen description of the plaintiff’s injury may significantly influence the outcome of the remoteness analysis.

Justice Martin’s risk-based approach assists in addressing this challenge, by “flipping the question around”. Her Honour framed the inquiry starting with the defendant’s conduct and asks:  what forms of harm did the defendant risk causing that rendered their conduct objectively unreasonable, and therefore negligent?

Where the defendant’s conduct creates a substantial and generalized danger to others, the risk may be described in broader terms. On the other hand, where the conduct was unreasonable because it exposed others to a narrower class of harms, a more specific risk description would be warranted.

Through this exercise, the risk is properly characterized and the injury that occurred is assessed as whether it represented a realization of that risk.

That said, Justice Martin was clear that both analyzing remoteness through the traditional lens of reasonable foreseeability and her risk-based approach are functionally equivalent, and that a trial judge will not err by merely adopting one conceptualization over the other.

The standard of review

Factual causation is a finding of fact subject to the standard of palpable and overriding error on appellate review. However, failing to undertake the counterfactual analysis in circumstances where it is necessary to properly apply the “but for” test is a legal error subject to the correctness standard.

Remoteness is a question of mixed fact and law and is therefore a decision generally entitled to deference absent palpable and overriding error, unless there is an extricable error of law (which would be reviewable on a correctness standard).

Takeaways

• Causation can be a complicated issue, particularly in complex medical negligence cases with numerous parties.

• Those who have struggled with the framework of reasonable foreseeability in the remoteness analysis may appreciate and find useful to adopt the approach articulated by Justice Martin.

• Farewell, “legal causation”, “proximate cause”, proximity”, and “cause-in-law”!