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Marijuana may be legal in California, but not behind the wheel. A lot of people don’t realize that driving under the influence of marijuana can get you a DUI. Do your research. There are many different ways to consume marijuana these days, from vape pens to edibles. Some have much stronger effects than others. Some stay in your system longer. By knowing ahead of time, you’ll also be planning ahead. Here’s a good rule of thumb. Just don’t drive. No matter how much or why, it’s still a DUI.

Prescription drugs can be stronger than you think. Be sure to check the label; you’d be surprised how often pain medication prohibits driving. Some of the strongest prescriptions are opioids like oxycodone, codeine, fentanyl, and hydrocodone. Not only are they highly addictive, they can seriously impair your ability to drive.

Marijuana Law

California’s Proposition 64, the Adult Use of Marijuana Act, went into effect November 9, 2016, making it legal for individuals 21 and older to use and grow marijuana for personal use. While smoking is permitted in a private home or at a business licensed for on-site marijuana consumption, smoking remains illegal while driving a vehicle, anywhere that prohibits smoking tobacco and in all public places.

Marijuana Affects Driving

  • Marijuana slows your reaction times and ability to make decisions. It affects the part of the brain that controls body movement, balance and coordination and can impair judgement and memory. Studies show that driving while under the influence of marijuana negatively impacts attentiveness, perception of time and speed. Impaired memory can affect the ability to draw from past driving experiences, especially in emergency situations.

  • The higher you are, the more risks you take while driving. Studies show that drivers with only a small amount of THC in their blood can feel the effects. They often try to be more cautious, driving slower than normal, even sometimes too slow. However, greater problems arise when increasingly larger doses of THC are present in the blood. These drivers tend to weave in and out of lanes more, react slower to traffic lights and unexpected obstacles and are less aware of their speed. Overall, higher doses of marijuana tend to cause greater impairment when it comes to driving.

  • The effect of marijuana is strongest during the first 30 minutes after consumption. People who drive immediately after using marijuana may increase their risk of getting into a crash by 25 to 35 percent. The impairing effect rises rapidly and remains for some time. These affects can be delayed if the marijuana is ingested rather than smoked.


Over the past 10-15 years, more Americans have begun taking more prescription and over-the-counter medications that can impair driving. The list is long, and includes sleep aids, pain killers, anti-depressants, stimulants, muscle relaxants, allergy medications, sedatives, antianxiety drugs and many more. These medications can be impairing for many hours after taking, sometimes up to 24 hours.

  • Always check the label of any medication and talk to your physician or pharmacist. Any mention of not driving, operating machinery or side effect that causes brain or physical impairment needs to be taken seriously.

  • Taking prescription medication according to doctor’s orders is not a valid legal excuse for driving while impaired.

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