Driving Under the Influence of Marijuana

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Driving is a daily task for most people and we rely on it heavily to get around. Unfortunately, some people abuse their right to drive and speed around under the influence of alcohol and narcotics which drastically impacts their ability to be safe drivers.  Marijuana is often classified the same as narcotics so you cannot drive under the influence. However, with many patients now accessing medical marijuana to help them manage illnesses daily, how will it impact their ability or right to drive?

Based on research, some countries record up to 38% to 41% of car accidents are caused by driving under the influence of alcohol and some involve narcotics too. Whether it’s due to occasional party events or heavy medical prescriptions the fatalities are real…

But what does that say about driving under the influence of marijuana?

Let’s look at the facts.

Marijuana remains to be one of the widely used substances in the world to date, which makes it susceptible for use when driving. The question as to whether marijuana impacts driving abilities goes back to its side effects, mainly: feeling of sleepiness or drowsiness, mood changes, altered sense of time and among others.

However, the uses and effects of marijuana vary amongst users. So how do you know if you are able or unable to drive safely while using the medication?

This article will pinpoint the facts on whether or not cannabis is safe to take while driving and how legalities in law can pose huge legal implications if caught driving under the influence of marijuana.

Impact of Marijuana to Driving

Under the Influence (DUI)

The effect of marijuana which is similar to a sedative, may certainly impact your driving. Things you need to know if you are a medical marijuana patient:

  1. It may cause delayed reactions to sudden changes in traffic
  2. You may feel sleepy and risk dozing for a second causing an accident
  3. Even if you feel fine, THC can remain in your system for up to 30 days

If you are caught driving under the influence due to an accident or a random police stop, the impact on driving under the influence of marijuana can be identified through some tests.

The tests vary from country and states. The below are just 3 common examples:

  • Blood test- (Colorado, Washington) if found with 5 nanograms per ml of blood in your system
  • Urine Tests- if you cannot have blood drawn
  • Saliva Tests- Usually done on the roadside and used on the scene to make inquiries

Although these tests identify the presence of substances in your body, they are not 100% reliable.

Authorities at any time can blame the presence of the substance as a cause for driving impairment even if you have long since stopped.

The studies connected to driving impairment when under the influence of marijuana have varied points since some remain inconclusive.

Furthermore, there is an implication by common state laws in California for example, that the use of marijuana doubles the risk of causing an accident. However, some research shows that drivers “high on pot” drove slower and were more cautious.

But how does it compare to driving under the influence of alcohol?

Laws regarding driving while under the influence of marijuana or alcohol varies from one state/place to another but are the two considered the same banana?

Let’s take a deeper look.    

Driving with Marijuana vs. Alcohol

Under the Influence (DUI)

We have discussed the debatable issue surrounding Weed vs. Alcohol and their Health Effects before. So now let us look at how both substances weigh up against each other with regard to driving.

Being under the influence of both can increase the risk of vehicular accidents, although marijuana may be less dangerous…


Blood alcohol concentration (BAC) limit for driving is 0.08%. Finding this concentration is an automatic violation.

It is also easy to test for alcohol via a breath test.

  • Drivers intoxicated with alcohol are said to speed more, exhibits erratic driving, and can’t focus when driving.
  • Risk to cause an accident up to 20x more


There is no objective test for impairment caused by Marijuana.

As previously noted it is a hard task to test for Marijuana compared to alcohol, you normally need a bodily fluid sample which then needs to be taken for testing.

  • Marijuana effects last only 2-8 hours; tests that prove positive in this regard are prone to be misread because it can stay in your body for 30 days but the effects are no longer felt.
  • Drivers under the influence of marijuana are said to be less aggressive and more cautious
  • Risk involving an accident only double


Driving and Marijuana: Legal Limitations and Repercussions

Illegal implications while driving with marijuana


Medicinal Marijuana has been made legal in twenty-four states in the USA. None of the states went on to allow driving a vehicle after using medical marijuana. Different states have different ways of approaching the issue of someone getting caught while being under the influence of marijuana, from actions as simple as issuing out a ticket, to incarceration.


In some states with Per Se DUI laws, detecting the presence of marijuana in a driver’s system during the time of offense means an established impairment. These states do not need to present more evidence. The presence of the substance in the driver’s system is enough to establish that the person was driving under the influence.

Measures to take if  you are under the influence of Marijuana and want to drive

  • Driving under the influence of marijuana whether in states that have or have not legalized medicinal marijuana still has its own specific sets of rules. It is the driver’s/user responsibility to check aggravating factors that may increase penalties related to driving under the influence of marijuana.
  • The best way is to NOT drive while under the influence of marijuana.
  • Medical marijuana Patients who drive must consistently follow the law regarding amounts, registration, and so on.
  • Before taking your medical marijuana plan ahead, make sure you do not need to be anywhere or have transport arranged.

Why you should not drive with Marijuana in your system

  1. States that have legalized medical marijuana and states with “per se” laws
    ~ Have not allowed driving under the influence of marijuana
    ~ Have specific sets of laws and penalties
  1. Research still shows a double increase of risk in accidents if you drive under the influence.
  1. Although effects in driving may be relatively less aggressive vs. effects when intoxicated with alcohol, since it impairs your mental alertness it still poses a risk to your safety.
  1.  Marijuana is still a controlled substance at large, and until more studies prove it is safe for use while driving, your best bet is not to drive if you have consumed some.
  1.  If you drive under the influence of marijuana it may lead to other aggravating circumstances in court or with the police, causing damage to your reputation and you risk being employed to future job opportunities.

Food for thought

Although marijuana is still an illegal substance in some countries around the world, we see more and more cultures slowly accepting the plant for its medicinal qualities and applications.

These patients of medical marijuana can be susceptible in driving under the influence, although it may not necessarily reduce their ability to be a safe driver. Considerations like your tolerance and amount consumed are taken into account and the fact that everyone is impacted differently.  

Medical marijuana is still new and being introduced to the public at large, so a lot more research on the topic of driving under the substance’s influence may be required but to remain safe and responsible, it is best to stay away from the wheel.

Do you think driving under the influence of Marijuana should be a criminal offense? 

Let us know your thoughts!

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