Colorado made national headlines when it became the first state to legalize marijuana use in January 2014. While it’s now legal to purchase and consume marijuana in the state, people who do so need to obey all relevant laws regarding its use, or they still risk tickets, fines or even jail time. Some of the most important laws are not new at all because they’ve applied to alcohol and other mind-altering substances for years, particularly Colorado’s DUI laws.

“Drive High, Get a DUI” Campaign

To remind people that driving under the influence applies to all potentially mind-altering substances, not just alcohol, the Colorado Department of Transportation recently launched a series of public service announcements focused on marijuana use. These television spots humorously point out that while doing many normal activities while under the influence of marijuana is now legal (such as grilling steaks, installing a TV or playing basketball with friends), driving is not. The ads target men between the ages of 21 to 34, which is the demographic that tends to have the highest number of DUIs, according to this press release from CDOT. The campaign follows extensive research into driver attitudes regarding marijuana use, which revealed that many people believed marijuana has no negative effect on their driving ability.

Legal Marijuana Limits

Just as with alcohol, there is a legal limit of marijuana detectable in the bloodstream to determine whether a person is driving under the influence. The law states that it is illegal to drive if you have 5 nanograms or more of active THC in your whole blood. The standard for alcohol is .08 percent blood alcohol content for a DUI and .05 percent for DWI (driving while impaired). Alcohol tends to correlate more closely with a person’s weight and the number of drinks a person has consumed, but marijuana does not affect everyone in the same way, and there is much more variance in how a given amount of marijuana will affect people. There can also be a significant difference depending on how the marijuana is consumed. Smoking tends to produce faster effects than consuming marijuana in food, for example.

There is some concern that the 5 nanogram limit is too stringent and may result in people being convicted of DUI who are not seriously impaired. Colorado law provides opportunity for a driver to challenge the charge of impairment, and a jury may find a driver not guilty of DUI despite a positive test result.

DUI Regulations and Penalties

Law enforcement officers in the state of Colorado are trained to detect impairment due to alcohol, marijuana or other substances, and many are specifically trained as Drug Recognition Experts. The training these officers receive makes them highly competent to detect signs of impaired driving and follow up with appropriate tests. Arrests are based on observed signs of impairment, not the results of testing.

Colorado has an express consent law, which requires drivers to consent to a chemical test if an officer has reasonable grounds to suspect impairment due to alcohol, drugs or both. Refusing a test under these circumstances means an immediate loss of driver’s license for one year, installation of a mandatory ignition interlock for two years, and required education and therapy.

A conviction of DUI in Colorado can result in fines, imprisonment, probation, public service, or required education and treatment. Additional penalties are levied if there were children in the car. People who use marijuana for medical reasons are not exempt from DUI laws. If a person shows signs of impaired driving or tests over the legal blood limit for THC, they can be convicted for DUI, regardless of the reason they use marijuana.