Scienter doctrine: proving liability when no law applies

In most of Canada, dogs get more than one free bite. Without a strict liability statute, a plaintiff has to dig into what the owner actually knew before the attack. That’s where scienter comes in, and knowing how to use this doctrine could make or break a case for personal injury claims.

What is scienter, and how does it work in Canada?

In animal attack cases, scienter refers to a form of strict liability. It means that once it applies, an owner is liable for damages regardless of whether they did anything wrong at the time of the attack.

The doctrine is as old as the common law itself. In the old pleading tradition, a plaintiff would allege that the defendant scienter retinuit (“knowingly kept”) a dangerous animal. That Latin phrase is where the doctrine gets its name.

The doctrine turns entirely on one question: did the owner know their animal was dangerous before it caused harm? If yes, the liability is strict. If no, the claim in scienter fails, and a plaintiff must rely on a claim for negligence instead.

In provinces where no strict liability statute protects dog-bite victims — such as British Columbia, Alberta, and New Brunswick — scienter remains the primary common law route to strict liability in animal attack cases.

Learn more about these strict liability laws for dog bites with this video:

Check out our article on “Personal injuries proceedings act: Limits, notices, and traps” to learn about the factors that lawyers and litigants should not miss in personal injury cases.

The two-animal framework under Canadian law

Before scienter applies, courts must classify the animal involved. Canadian law divides animals into two categories:

Animals ferae naturae

These are species considered dangerous by nature, such as bears, lions, tigers, wolves, and, as held in McLean v. Thompsons, 2009 BCPC 0415, wolf-dog hybrids.

For these animals, no proof of the owner’s prior knowledge is required. Since their dangerous character is presumed by law, strict liability automatically attaches.

Animals mansuetae naturae

On the other hand, these are the species that are ordinarily harmless by class, such as dogs, cats, horses, and cows. For them, the presumption of harmlessness is rebuttable, and scienter must be proven.

As confirmed in Belton v. Spencer, 2021 ONSC 2029, the presumption that a domestic animal is harmless is rebuttable. It means that a plaintiff can displace it, but the burden rests with them to do so.

Three things that must be proved in a scienter claim

As set out in Janota-Bzowska v. Lewis, 1997 CanLII 3258 (BC CA), a plaintiff must establish three elements to succeed in a scienter claim involving a domestic animal:

• ownership: that the defendant was the owner or keeper of the animal
• propensity: that the animal had manifested a propensity to cause the type of harm that occurred
• knowledge: the owner knew of that propensity

All three must be proven on a balance of probabilities. More importantly, failure on any one of them is fatal to the scienter claim.

Whether scienter applies to kennels and vet clinics

The short answer is yes, and the case for liability against commercial operators is often stronger than it is against a private owner.

Scienter attaches not only to owners, but also to “keepers,” who harbours and controls an animal. As stated in McLean, the liability of keepers is well established at common law: responsibility attaches to whoever harbours and controls the animal, not solely to its owner.

What counts as dangerous propensity in court?

In most cases, this is where scienter claims are won or lost. The animal must have previously shown a tendency to cause the same type of harm, and not just any bad behaviour.

In McKinlay v. Zachow, 2018 ABQB 365, it was held that the fact the defendant’s American Staffordshire Terrier mix had barked at strangers, or run without restraint when off leash, did not establish a propensity to bite a human in the face. As that particular type of harm had never occurred before, the scienter claim failed on this basis alone.

What can establish propensity

Canadian courts have consistently held that the prior behaviour need not be precisely the same as the harm that occurred. This principle was applied by the court in Evans v. Berry, 2024 BCCA 103.

Instead, what the plaintiff must show is a meaningful connection between the prior behaviour and the injury. The evidence that courts have considered includes:

• prior bites or attacks, whether or not they were reported
• lunging, snapping, or aggressive charging at people
• the owner’s decision to muzzle the animal for routine activities (in McLean, the wolf hybrid Harley was muzzled for veterinary visits)
• the purpose for which the animal was kept (in Prasad v. Wepruk, 2004 BCSC 578, a defendant who kept a large dog chained at his scrapyard to deter intruders was found to have known of the dog’s vicious propensity, given its openly aggressive behaviour toward neighbours and passersby)
• precautionary measures taken by the owner, such as choke chains and secure yards; responsible containment can itself signal an owner’s awareness of risk

The Evans v. Berry lesson

The Evans case is a cautionary tale for plaintiffs. Bones, a mixed-breed rescue dog, had nipped three people’s ankles, bitten another dog hard enough to draw blood, and bitten the owner’s father hard enough to break skin. Yet both the trial court and the Court of Appeal found that scienter had not been made out.

The reasons matter:

• the nipping incidents were characterised as not breaking skin; this is a different type of harm from the three-inch facial laceration Evans suffered
• the father’s bite was found likely accidental, as both Bones and the father were reaching for the same food at the same time
• the dog trainers had told the owners no muzzle was needed
• the veterinarian after the father’s bite did not recommend muzzling or quarantine

Where professional advisors, such as trainers and veterinarians, have reassured an owner that the animal is not dangerous, courts are reluctant to find that the owner subjectively knew otherwise.

When should plaintiffs choose negligence over scienter?

Scienter and negligence are independent causes of action. Most personal injury lawyers plead both in the alternative, and for good reason; a claim that fails in scienter may still succeed in negligence.

The key difference is the knowledge standard. Scienter requires proof that the owner actually knew of the animal’s dangerous propensity. On the other hand, negligence asks only whether the owner knew or ought to have known that the animal was likely to create a risk of injury to others.

That objective standard is often easier to satisfy. In McKinlay, while the scienter claim failed because the dog had no history of the relevant dangerous behaviour, the negligence claim succeeded.

In that case, Zachow knew his dog was classified as a restricted breed under City of Edmonton Bylaw 13145 (the Animal Licensing and Control Bylaw), knew the bylaw required leashing and muzzling in public, opened the van door to allow public access to the dog, and took no steps to stop the plaintiff from approaching. The court found that a bite was within the range of likely consequences.

More about the laws on dog liability, specifically under Ontario’s statute, with this video:

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When statutory breach strengthens a negligence claim

The Supreme Court of Canada confirmed in Ryan v. Victoria (City), [1999] 1 SCR 201, that a statutory breach is not automatically negligence, but it is evidence of it. In animal attack cases, this means:

• municipal leash law violations can support a negligence claim even where scienter fails
• breed-specific bylaw classifications, while insufficient on their own for scienter, can establish foreseeability for negligence purposes
• a plaintiff does not need to prove the specific harm was foreseeable, only that physical harm of that general kind was

The last one is a principle restated in Wilk v. Arbour, 2017 ONCA 21, citing Bingley v. Morrison Fuels, 2009 ONCA 319.

Scienter: the doctrine that barks for strict liability

In these cases, the owner’s knowledge is everything, and building that evidentiary picture before trial is what separates a recoverable claim from one that never had a chance.

Bookmark Canadian Lawyer’s Personal Injury page to read more articles that can help legal professionals, aside from the doctrine of scienter in animal liability cases.