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What is negligence?

Many lawsuits and criminal cases hinge on the concept of “negligence.” It’s especially common in personal injury law, since one party is claiming that another did — or didn’t do — something that caused their injury. But it can be hard to define and prove.

How Canadian law weighs negligence

People are generally considered to have a duty to ensure that their actions do not expose other people to unreasonable risk of harm. This is called a “duty of care.” If someone fails in that duty, they could be liable for negligence.

The Supreme Court of Canada defined negligence as conduct that creates “an objectively unreasonable risk of harm.” This can include intentional and unintentional actions, or even lack of action, such as not shovelling your sidewalk in the winter.

To avoid liability for negligence, you must exercise what the court calls “the standard of care that would be expected of an ordinary, reasonable and prudent person in the same circumstances.” 

So what does “reasonable” mean? The courts consider three questions:

  1. Could the accused have anticipated their conduct would create harm?
  2. How serious was the harm done?
  3. What cost or burden would the defendant have incurred to prevent the harm?

Generally, courts use what’s called the “but for” test to determine negligence. That means a plaintiff must prove that “but for” the supposedly negligent conduct, the accident wouldn’t have happened.

When weighing whether a defendant was negligent, the courts consider the following:

  • Whether a duty of care existed.
  • Whether the accused failed in that duty.
  • Whether their failure caused any harm.

Establishing that duty of care can be tricky, especially as plaintiffs will often name multiple parties. Courts have to look at the “proximity” of some defendants.

In one case, an 18-year-old Ontario woman sued a drunk driver who struck her car, severing her spine. She, in turn, sued the hosts of the party where the driver got drunk in the first place. The judge had to consider whether the host had enough proximity to the victim to create a duty of care. The case went to the Supreme Court, which ruled the hosts were not liable in part because the party was BYOB (bring your own booze) so the hosts didn’t serve the driver and couldn’t monitor his intake.

“Negligence” can cover a wide swath of harms, from slipping on a sidewalk to medical malpractice and even fatal accidents. The law identifies different types of negligence according to the type and the seriousness of the incident.

Gross negligence implies a flagrant disregard for the consequences or the safety of others. Where regular negligence is basically the failure to be careful, gross negligence is closer to abject recklessness. It’s not intentional though; a knowing disregard for care and safety would be called wilful misconduct.

Criminal negligence is "wanton or reckless disregard for the lives or safety of others." Driving while intoxicated is a typical example. This can be further categorized into Criminal Negligence Causing Bodily Harm or Criminal Negligence Causing Death.


Read more:

Criminal negligence:

Ontario’s Negligence Act:

B.C.’s Negligence Act: