Negligence Claims in Ontario: What You Need to Prove

Negligence means failing to exercise reasonable care, causing harm to someone who was owed a duty of care. It’s not about bad intentions; it’s about carelessness. 

The person didn’t mean to hurt you, but their failure to act reasonably caused your injuries or losses. Common negligence scenarios include car accidents from careless driving, slip and fall injuries on poorly maintained property, professional errors by lawyers or accountants, medical malpractice from substandard care, and defective products causing injury.

To succeed in a negligence claim, you must prove all four elements on a balance of probabilities. If you fail to prove even one element, your claim fails.

First, you must establish a duty of care. The defendant owed you a legal duty to act carefully. 

Duty of care exists when a relationship creates responsibility, such as doctor-patient, and when the defendant’s actions could reasonably harm you. 

In most cases, establishing duty of care is straightforward because the relationship clearly creates responsibility. Drivers owe other road users a duty to drive safely, property owners owe visitors a duty to maintain reasonably safe premises, and professionals owe clients a duty to meet competency standards.

Second, you must prove breach of duty, also called breach of the standard of care. 

Courts don’t expect perfection, just reasonable care given the situation. Factors courts consider include what risks were foreseeable, how serious potential harm was, how difficult avoiding the harm would have been, and relevant industry or professional standards. A driver texting while driving breaches the standard, as would a store owner leaving a spill on the floor for hours, or an accountant failing to follow standard accounting practices. 

Expert evidence is often needed to establish professional standards.

Third, you must prove causation. 

The defendant’s breach actually caused your injuries or losses. 

This involves two types of causation: factual causation (the “but for” test – but for the defendant’s negligence, would you have suffered the harm?) and legal causation or remoteness (the harm must be a reasonably foreseeable consequence of the negligence). 

Causation can be challenging when pre-existing conditions complicate injury claims, multiple possible causes exist for the harm, or when proving professional negligence caused specific financial losses.

For example, if you’re injured in a car accident but had previous back problems, you must prove the accident caused new injuries or worsened existing conditions.

Fourth, you must prove damages. You suffered actual harm; physical injury, property damage, or financial loss. No harm means no claim, even if negligence occurred. Damages you can recover include:

• Medical expenses and treatment costs
• Lost income and reduced earning capacity
• Property damage and repair costs
• Pain and suffering
• Loss of enjoyment of life
• Future care costs

Quantifying damages requires evidence such as medical records and doctor reports, wage statements and employment records, repair estimates and invoices, expert reports on future losses, and testimony about impact on daily life.

Even if you prove the four elements, defendants can raise defenses reducing or eliminating liability. 

The most common defense is contributory negligence: you were partially at fault for your own injuries. Ontario follows contributory negligence rules where fault is apportioned between parties. 

If you’re found 30% at fault and the defendant 70% at fault, your damages are reduced by 30%. Examples include a pedestrian jaywalking hit by a speeding car where both are negligent, or a slip and fall victim wearing inappropriate footwear despite warning signs.

Another defense is voluntary assumption of risk, though this rarely succeeds. It requires proving you had full knowledge of the specific risk, voluntarily chose to accept that risk, and your acceptance was explicit or clearly implied. 

Simply knowing an activity has some risk isn’t enough; you must have specifically accepted the exact risk that materialized.

Defendants also argue no breach occurred: that they met the standard of care and acted reasonably given the circumstances. This is defended by showing they followed industry standards, took reasonable precautions, the accident was unavoidable despite reasonable care, or expert evidence supports their conduct was acceptable. 

Similarly, defendants may argue no causation exists: that their actions didn’t actually cause your harm because injuries existed before the incident, something else caused your losses, or the connection between breach and harm is too remote.

Facing a negligence claim? Our tort litigation lawyers can assist. Contact us at 416.901.9984 or info@pintoshekib.ca for a confidential consultation to assess your claim.