The Truth About Driving While High

Driving, while under the influence of cannabis, does not deter the driver’s ability to avoid accidents. Being under the influence of cannabis can significantly slow the reaction time of drivers. But does the impairment of driving equate to other drugs like alcohol?

There have been many statistical reviews done on whether or not cannabis impairs the driver’s ability to drive. Included with these studies are comparisons on whether or not cannabis is worse than alcohol or other drug impairment. These studies seem to contradict each other, and in some studies, scientists concluded that cannabis does not impair driving whatsoever. However, there is no doubt that the effect of smoking cannabis before driving is not as good as driving sober. In other words, it is better to operate a vehicle without any drug impairment than to drive with one.

Under the influence?

The use of cannabis affects the brain and is much different from alcohol. Cannabis will change a person’s attention, perception, vigilance, and rational use of the mind. The effects of cannabis in the brain show that those who are under the influence have slower reaction times. Drivers who are under the control of cannabis tend to drive at lower speeds and keep distances that are abnormally larger from the car ahead of them.

THC is the main component within the drug cannabis and gives the user a euphoric “high” feeling. When one uses cannabis in large amounts, the high concentration of THC in the blood will determine the number of impairments that the person has. However, most persons that use cannabis tend to have a higher tolerance overall. Persons who use cannabis regularly could feel like they’re not under the influence of THC in their blood.

So how do police officers determine whether someone is under the influence of cannabis when they pull somebody over? For the most part, police officers will decide whether or not the driver is under control with standardized field sobriety tests. These tests are a series of off-road challenges that include the one-leg stand and the walk turn test. Failure to complete these tests could prompt a saliva test for THC levels.

The best strategy to avoid being arrested for under the influence charges is to understand whether or not you can pass the series of off-road challenges if an officer asked you to do so. You should not drive if you believe that you cannot stand on one leg for an extended period or walk and turn without stumbling.

Cannabis and Accidents

There has been many studies completed on accidents and cannabis throughout the world. Some of the studies will state that cannabis use is not related to an increase in accident risk. Some studies believe that driving under the influence from the use of cannabis will increase the risk of an accident.

The differences between the statistical studies are due to the fact that the different subjects that have been analyzed have different situations. The subjects that had an accident were caught under the influence of cannabis. The problem with the studies is that the persons being studied did not provide when they used the drug before driving their vehicle. This creates a scientific problem. To get an accurate estimate on whether or not cannabis will affect a person’s ability to drive, there needs to be several factors defined:

  • When the person used cannabis
  • When the person started driving under the influence
  • Cannabis laws in the area of study
  • THC level estimates
  • Type of accident that occurred (i.e. fender collision or head-on collision)

Though accurate estimates are not available, the conclusion amongst a majority of the studies on cannabis impairment and driving showed that cannabis affected drivers are at a higher risk of an accident. Impairments that stem from the use of cannabis while driving include the ability to control steering, speed variability, car following, reaction time, and positioning in lanes.

However, when compared to other drugs out there, cannabis ranks low statistically when it comes to the risk of injury or fatal accidents. Cannabis does not have statistically significant odds of increasing injuries or fatal accidents. Drugs that are statistically significant in increasing the odds of injuries and fatal accidents include:

  • Opiates
  • Alcohol
  • Anti-anxiety medications
  • Sleep medicine
  • Cocaine
  • Amphetamines


There are many experts on the issue of driving under the influence of cannabis in your system. Many experts and the studies that were done on the subject tend to disagree with one another. However, the majority of experts and studies believe that the influence of cannabis, including THC in the blood system, affects a person’s ability to drive safely.

Some believe that you can take cannabis and drive several hours after taking the drug. This advice is not good because the effect of cannabis is based on the user’s overall tolerance to the drug. A person who has a high tolerance to the drug may drive under the influence at a different level than someone who has a low tolerance. Whether or not a person has a high or low tolerance, the person should understand that if pulled over, the police will challenge the person’s ability to control a vehicle. Off-road balance tests will be used if a police officer believes you are under the influence of a drug.

You should never enter a vehicle under the influence of any drug. You should understand that you must have full control of the vehicle to safely drive from point A to point B. Never enter in a car if you are stumbling or having difficulty walking and thinking clearly. This is regardless of what drug you take. In other words, don’t take a chance, don’t drive high!

For more detailed information regarding drug-impaired driving laws and processes in Canada and throughout the provinces, click right here to learn more!