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When thinking about a DUI, we almost always assume the driver was under the influence of alcohol. Maybe they’re driving home from the bar. Or coming from a friend’s party where they had a few cold ones. We know the common scenarios and – in theory – that helps us to avoid them.


Driving under the influence of marijuana, however, can also be a reason for an arrest.


With alcohol, the driver of a vehicle can be arrested if they have a BAC or blood alcohol content over 0.08. With marijuana, the legal limit in Colorado is 5 ng/mL of THC in the blood – and can only be determined by a blood test.


Recently, many juries in our state have acquitted marijuana users of driving under the influence even when a blood test shows they are over the legal limit of 5 ng/mL. But you can’t assume that’s going to happen. Despite these acquittals, it’s important to know the facts about marijuana and driving or you could face serious consequences.


Does Marijuana Affect the Ability to Drive?


Marijuana is considered to be a drug, which, by definition, is a substance that has a physiological effect on the body. Marijuana can affect reaction time, short-term memory, concentration, hand-eye coordination, and perception of time and distance.


Though, it may be difficult to judge if you are experiencing any level of impairment, using marijuana definitely puts you at risk of driving impaired.


How Can Law Enforcement Determine if I am Impaired by Marijuana Use?


No matter the level of THC in your blood, police officers base arrests for driving under the influence of marijuana on observed physical signs of impairment.


Colorado law enforcement officers are trained in detecting impairment caused by drugs. Some officers get further training in Advanced Roadside Impaired Driving Enforcement (ARIDE) and there are also Drug Recognition Experts (DRE) on staff to determine impairment from many different substances.


What if I Refuse a THC Blood Test?


If you refuse to take the blood test to determine the amount of THC in your blood, Colorado will revoke your driving privileges and consider you a high-risk driver. The consequences for refusing a blood test can include a mandatory ignition lock for 2 years and alcohol education and therapy classes.


What if I Have Marijuana or Marijuana Paraphernalia in My Vehicle?


In accordance with Colorado’s open container laws, it is illegal to have marijuana in the passenger area of a vehicle if it is in an open container, a container with a broken seal, or there is evidence that marijuana has been used.


In Colorado, it is illegal to consume marijuana on any public roadway.


How Can I Prevent an Arrest for Driving Under the Influence of Marijuana?


Denver Drug Lawyer


The Colorado Department of Transportation has been working with the marijuana industry, along with other state and local agencies, to develop education outreach and policies to inform marijuana users about the dangers of driving while impaired.


Taxis or ride-sharing services like Lyft and Uber are available if you need to go somewhere so you don’t have to drive.


No DUI Colorado is an educational resource for the Colorado community about impaired driving and substance abuse behaviors with regards to both alcohol and marijuana.


What if I am Arrested for Driving Under the Influence of Marijuana?


If you are arrested for driving under the influence of marijuana, it’s important to consult with a skilled criminal defense attorney who has experience with drug offenses and driving under the influence of marijuana. A criminal defense lawyer will be able to look at your charges and determine the best course of action for your case.


About the Author:


Kimberly Diego is a criminal defense attorney in Denver practicing at The Law Office of Kimberly Diego. She obtained her undergraduate degree from Georgetown University and her law degree at the University of Colorado. She was named one of Super Lawyers’ “Rising Stars of 2012” and “Top 100 Trial Lawyers in Colorado” for 2012 and 2013 by The National Trial Lawyers. Both honors are limited to a small percentage of practicing attorneys in each state.  She has also been recognized for her work in domestic violence cases.



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