The Effects of Cannabis on Driving: Navigating the Dangers from a Personal Injury Law Perspective

April 10, 2026, Kitchener, Ontario

Posted by: Robert Deutschmann, Personal Injury Lawyer

The Effects of Cannabis on Driving: Navigating the Dangers from a Personal Injury Law Perspective

In 2018, Canada made history by legalizing cannabis nationwide. Today, its use is fully recognized, widely accepted, and seamlessly integrated into the daily lives of many Canadians for both medical and recreational purposes. However, a critical distinction remains: just because a substance is legal for adult consumption does not mean it is safe to use before getting behind the wheel of a car.

At Deutschmann de Koning Law, we have spent over 30 years representing victims of motor vehicle accidents in Kitchener and the surrounding areas. Through our extensive experience in personal injury and disability law, we have seen firsthand the devastating consequences of impaired driving. In this post, we explore how cannabis affects driving abilities and highlight the profound dangers from a personal injury law perspective.

How Cannabis Impairs Driving Abilities

While the stigma surrounding cannabis has faded, the physiological realities of tetrahydrocannabinol (THC), the primary psychoactive compound in the plant, remain unchanged. Some users mistakenly believe that cannabis makes them a more cautious or focused driver. However, scientific studies and traffic safety data consistently prove otherwise.

THC actively interacts with the brain’s endocannabinoid system, causing several impairments that directly affect driving:

• Slower Reaction Times: Driving requires split-second decision-making. Cannabis significantly delays the brain's ability to process unexpected events, meaning a driver under the influence will take longer to hit the brakes when a pedestrian steps out or a car stops suddenly.
• Altered Perception of Time and Distance: Safe driving relies on accurately judging the speed of oncoming traffic and the distance between vehicles. Cannabis distorts depth perception, leading to dangerous lane changes, tailgating, and intersection collisions.
• Decreased Motor Coordination: Operating a vehicle requires the synchronized use of hands, feet, and eyes. THC impairs fine motor skills, leading to lane drifting and overcorrecting steering.
• Impaired Concentration: Driving is a complex, divided-attention task. Drivers must monitor speed, mirrors, traffic signals, and surrounding vehicles simultaneously. Cannabis reduces a driver's ability to focus on multiple stimuli, making them highly susceptible to distraction.

Legal to Consume Does Not Mean Legal to Drive

Because cannabis has been legal in Canada for years, some drivers have developed a false sense of security. It is vital to understand that driving under the influence of cannabis remains a serious criminal offense under the Criminal Code of Canada. Law enforcement officers across Ontario are equipped with specialized training and roadside oral fluid screening devices to detect recent cannabis consumption.

However, beyond the criminal charges, fines, and license suspensions, there is another deeply impactful side to this issue: the realm of personal injury law.

The Dangers from a Personal Injury Law Perspective

When a driver chooses to operate a vehicle while impaired by cannabis, they are actively breaching their duty of care to everyone else on the road. From a personal injury perspective, this has massive implications.

1. Establishing Negligence and Liability

In a personal injury lawsuit, the injured party must prove that the at-fault driver was negligent. Evidence that a driver was under the influence of cannabis at the time of the crash serves as powerful proof of negligence. If you are struck by a driver who was high, their impairment will play a central role in holding them legally and financially accountable for your injuries.

2. Severe and Catastrophic Injuries

Because impaired drivers often suffer from delayed reaction times, they frequently fail to brake or take evasive action before a collision. As a result, accidents involving cannabis impairment tend to happen at higher speeds and with greater force. Our personal injury lawyers routinely see victims suffering from severe trauma, including traumatic brain injuries (TBIs), spinal cord damage, complex fractures, and chronic pain.

3. Complications with Insurance Claims

In Ontario, auto insurance policies require drivers to operate their vehicles within the bounds of the law. If an at-fault driver is convicted of impaired driving, they may breach the conditions of their insurance policy. While this can complicate how the at-fault driver is covered, the injured victim still has strict legal avenues to pursue compensation for pain and suffering, lost wages, and future medical care. Navigating these complex insurance disputes is exactly where experienced legal counsel becomes necessary.

Protecting Your Rights After an Accident

If you or a loved one is injured by an impaired driver, it is crucial to protect your rights immediately. Always seek medical attention first, ensure a police report is filed, and document the scene if you are able. Most importantly, reach out to a trusted personal injury legal team before making any statements to the insurance companies.

With the evolution of our firm into Deutschmann de Koning Law in 2024, partners Rob Deutschmann and Nick de Koning continue a legacy of excellence that spans over three decades. We understand the physical, emotional, and financial toll an accident can take. If you have been injured due to someone else's negligence, our dedicated team in Kitchener is here to advocate fiercely for the compensation and care you deserve.

About Deutschmann de Koning Law

Deutschmann de Koning Law serves South-Western Ontario with offices in Kitchener-Waterloo, Cambridge, Woodstock, Brantford, Stratford and Ayr. The law practice of Robert Deutschmann and Nick de Koning focuses almost exclusively in personal injury and disability insurance matters. For more information, please visit www.ddinjurylaw.com or call us at 1-519-742-7774.