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How a Cop Will Decide if You’re High While Driving

In some of our past blogs, we touched on marijuana laws and what you can get in trouble with. In addition, we’ve covered the laws in Colorado that you need to know if you’re using marijuana. In today’s blog, we’ll be covering one of the most asked questions: Can a cop tell if a person is high when he or she is driving? Unlike alcohol, there’s no surefire way to tell if someone is high when they are driving. There’s no breathalyzer that detects that amount of marijuana or the prescription drugs in your system. There’s an idea that if you’re high and there’s no evidence of you being high, then a police officer is unable to do anything. As a criminal lawyer in the Fort Collins area, we want you to be as educated as possible, so you know if your rights are being violated. One of the many focus areas that we deal with at Roselle & Breitigam, P.C. are drug charges. We also have experience in DUIs, student crimes defensefelonies, and misdemeanors defense.

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You may think that just because you aren’t drunk it’s fine to drive high. After all, you think you’re fine to drive because your abilities are not as impaired as they would be with alcohol. However, this mindset is wrong. When you consume cannabis, just like alcohol, your ability to drive will be impaired. As a matter of fact, you’ll react similarly in critical situations as you would if you had drunk alcohol.

Marijuana is just as dangerous to drive on as alcohol. Cannabis will impair your reaction time, your hand-eye coordination, and your perception of time and distance. It will also affect your short-term memory and your concentration. You could get into a car thinking you’re fine, but as your perception of distance is obscured, you may think it’s okay to run that yellow light when in fact, you’ll find yourself in an accident. While you may think that driving high makes you a better driver, you’re unfortunately not. In addition, it’s illegal to drive high and can be deemed as a prosecutable offense no matter if marijuana is legal or those prescription drugs you’re taking were prescribed by a doctor.

To give you a good idea of the statistics about driving while high, we compiled some information from the Colorado Department Of Transportation. “One-third of fatalities involved an impaired driver, that is 196 fatalities. There have been more than 17 percent of DUI arrests in the State of Colorado by State Patrol in the year 2016 for marijuana. About 55 percent of marijuana users think that it’s safe to drive under the influence of marijuana.”


There is a legal limit on marijuana while driving, but it’s very difficult to determine for the user. According to Colorado law, a driver is allowed to have five nanograms of active tetrahydrocannabinol in their system. Tetrahydrocannabinol, or THC, can be detected in the blood if you’re tested. While testing for marijuana is very difficult since you can’t take a urine test for it, you can be asked to take a blood test to determine the amount of THC in your system. Keep in mind, however, that many law officers will go off an arrest that’s based on the observed impairments of the driver no matter what the level of THC may be.


One of the reasons you may think that driving while high is okay is because a police officer is unable to spot the sights. Just because you are unable to test for marijuana at this point in time doesn’t mean that you should think it’s okay to drive while you’re stoned. A police officer can tell the signs; as a matter of fact, they are trained to be able to tell the signs if someone is high. The training is called Advanced Roadside Impaired Driving Enforcement. Colorado law enforcement officers have the training to detect if someone is impaired with either alcohol or drugs. They are even specially trained to detect drug recognition and are experts in the field. This means that a cop will be able to see physical signs of drug impairment a lot easier than someone else would.

In addition, the Drug Recognition Experts (DRE’s) are seen as one of the ways that have helped to reduce drugged driving because they can spot if someone is high or not. According to the Colorado Department Of Transportation, between the years 2012 and 2014, “there was a 68 percent increase in the number of Drug Recognition Experts who trained in Colorado.” For the best way to avoid a situation that involves you being reprimanded by a Drug Recognition Expert, you should stay away from driving while impaired on either marijuana or alcohol.

For more information about drug charges, stay tuned for our next blog.