Colorado DUI, DUI per se and DWAI laws

Colorado law prohibits driving under the influence of alcohol or drugs that cause impairment. Several statutes exist that govern various specific aspects of this general prohibition.

Everyone understands that a driver who has taken a substance that affects ability may be driving unsafely and runs the risk of causing significant harm to self and others. Each state has its own approach to issues such as specific substances, how to determine impairment and applicable penalties. This how Colorado defines these crimes.


DUI, or driving under the influence, means driving after consuming alcohol, drugs or a combination of alcohol and drugs and becoming impaired as a result. Drivers violate this law even if the substance causing the impairment is legal to use, such as medical marijuana, a legally prescribed drug and even an over-the-counter medication. This law prohibits impairment, not amounts. As people may have widely differing tolerances to potentially risky substances, the best approach is not to drive if you are not sure of the effect.

DUI per se

In the case of alcohol, Colorado law considers you impaired if your blood alcohol content (BAC) is 0.08 or over, no matter if you did not suffer actual impairment to your driving skills. Similarly, a THC level of 5ng/ml or higher creates an inference of impairment from marijuana.


DWAI, or driving while ability impaired, prohibits drivers from getting behind the wheel while under any degree of impairment due to drugs, alcohol or both.

Evidence of impairment

In most cases, police officers may stop a driver because they notice an erratic driving pattern that gives rise to suspicion of impairment. They may also make the stop in the course of operating a sobriety checkpoint. They may administer a breath or blood test to detect BAC. The presence of drugs typically requires a urine or blood test, though some Colorado State Patrol troopers have recently begun using mouth swabs to test for marijuana. Other types of evidence in such cases may include the officer’s observations, witness statements and the driver’s general demeanor.

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