Drugged driving puts a driver, passengers, and others on the road at serious risk. For that reason, it is illegal in all 50 states and Washington D.C. to drive under the influence of alcohol, marijuana, opioids, methamphetamines, or any potentially impairing drug - either over the counter or prescribed.
Effects of Marijuana on Driving
According to the National Institute of Drug Abuse, after alcohol, marijuana is the drug most often found in the blood of drivers involved in crashes. Tests for detecting marijuana in drivers measure the level of delta-9-tetrahydrocannabinol (THC) in the blood. Since THC can be found in body fluids for days or even weeks after use, more research is needed to understand its role in drugged driving crashes.
Marijuana can affect motor and thinking skills important for driving including:
- Time and distance perception
- Reaction time
- Lane tracking
According to the Michigan Regulation and Taxation of Marihuana Act (MRTMA):
- Drivers over the age of 21 years can transport 2.5 ounces or less of marihuana with no more than 15 grams of marihuana in the form of a marihuana concentrate.
- Drivers cannot operate, navigate, or be in physical control of any motor vehicle, aircraft, snowmobile, off-road recreational vehicle, or motorboat while under the influence of marihuana.
- Drivers cannot consume marihuana while operating, navigating, or being in physical control of any motor vehicle, aircraft, snowmobile, off-road recreational vehicle, or motorboat.
- Drivers and/or their passengers are not allowed to smoke marihuana within the passenger area of a vehicle upon a public way (road).
- Drivers and passengers cannot transport marihuana into Canada.
The penalties for operating under the influence of marihuana are the same as operating under the influence of alcohol even if a driver shows no signs of impairment. The only exception is if a person has a valid medical marihuana card.
Fines and punishment could include:
- Up to 93 days in jail
- Up to a $500 fine
- Community service hours
- License suspension
- Six points on a person's driving record
Penalties increase if a driver has minors in the vehicle.
Mixing Marijuana with Alcohol
Alcohol slows the activity of the central nervous system including the brain. As a result, thinking, reasoning, and muscle coordination are impaired. Those skills are essential to operating a vehicle safely.
Using marijuana and alcohol at the same time can impair a person more than using either one alone. Mixing the two may increase both risks and side effects. While researchers are still working to completely understand how the mind and body are affected, possible side effects could be physical (e.g., nausea or vomiting) or psychological (e.g., panic attacks, increased anxiety, or paranoia).
In addition, using both alcohol and marijuana raises the risk of getting severely intoxicated. Those who become too intoxicated have less control of themselves and less awareness of their surroundings. It could also lower their ability to make good choices. Even if someone has had "just a little" of each substance, driving under the influence of alcohol or marijuana is illegal and dangerous.
Driving and Other Drugs
Although many over the counter and prescription medications do not hurt a person's ability to drive, some can have side effects and cause reactions that may make it unsafe to drive.
Over the counter drugs may cause drowsiness, dizziness, nausea, irregular heartbeat, or shakiness.
Prescription drugs such as opioids, sedatives, muscle relaxants, and some antidepressants can cause drowsiness, trigger nausea, affect judgement, and decrease coordination, all of which can impair driving ability.
Read and follow all warning labels on over the counter and prescription medications before driving. Warnings against “operating heavy machinery” include driving a vehicle.
How Often Does Drugged Driving Cause Crashes?
Impaired drivers cannot accurately assess their own impairment which is why no one should drive after using any substances. It is hard to know exactly how many crashes are caused by drugged driving because:
- A good roadside test is not yet available to measure drug levels in the body.
- Some drugs can stay in a person's system for days or weeks after use which makes it hard to know when the drug was used and how, or if, it impaired driving ability.
- Police do not usually test for drugs if a driver has reached an illegal blood alcohol level because there is already enough evidence for a driving under the influence charge.
- Many drivers who cause crashes are found to have drugs and alcohol, or more than one drug, in their system making it hard to identify which substance had the greater effect.
If using alcohol, marijuana, over the counter or prescription medications, or any combination of legal or illegal substances:
- Choose not to drive and remind friends and family to do the same.
- Identify a trusted designated driver who will not drink or use drugs when out with a group of people.
- Plan on getting a ride home from someone who has not been drinking alcohol and/or using drugs, using a rideshare service, or calling a taxi.