Marijuana DUIs in Colorado: How ‘Driving While High’ Is Investigated and Charged
Understanding Marijuana DUIs in Colorado
Colorado allows adults to use marijuana recreationally, but driving under the influence of cannabis remains illegal. State law treats marijuana-related impairment with the same level of seriousness as alcohol DUIs. Police officers in Denver and throughout Colorado use both scientific testing and observational methods to build these cases, which can make them complicated to fight in court.
Anyone charged with a marijuana DUI faces strict penalties, even for a first offense. Understanding how officers investigate these cases and how prosecutors use evidence helps drivers protect their rights and know what to expect after an arrest.
What the Law Says About Marijuana and Driving
Under Colorado law, a driver can be charged with a DUI or a DUID (Driving Under the Influence of Drugs) if they are impaired in any way by marijuana. The state has set a legal THC blood limit of 5 nanograms per milliliter of whole blood. Drivers testing at or above this level are presumed to be under the influence.
However, even a driver who tests below 5 ng/mL can still face a DUI if police observe signs of impairment. This means that much of the state’s enforcement depends on officer judgment, which can be subjective and open to interpretation.
How Marijuana DUIs Are Investigated
1. Traffic Stops and Field Observations
Marijuana DUI investigations often begin with a traffic stop. Officers look for behaviors like weaving, delayed reactions, or failing to signal. Once contact is made, they may note signs such as the smell of cannabis, bloodshot eyes, or slowed speech. These early observations often form the foundation of the case.
2. Field Sobriety Tests
Standardized field sobriety tests assess a driver’s balance, coordination, and mental focus. These include tasks like walking in a straight line or following a pen with the eyes. While designed for alcohol impairment, police still use them for suspected drug impairment. Results are recorded and may be supported by video evidence.
3. Drug Recognition Experts (DREs)
Some Colorado departments call in trained Drug Recognition Experts to evaluate suspected marijuana impairment. DREs check for physical indicators such as enlarged pupils, slowed reaction time, and muscle tremors. Their testimony can carry significant weight in court, even when chemical tests show borderline or inconsistent THC results.
4. Chemical Testing
Colorado’s express consent law requires drivers suspected of DUI to take a chemical test—usually a blood draw—within two hours of the stop. The purpose is to measure active delta-9 THC levels. Blood tests are the most common because they are more reliable for measuring active THC than saliva or urine tests.
Failing or refusing to take the test can lead to immediate administrative license suspension, regardless of whether the person is later convicted in court. Refusal can also trigger additional legal penalties.
5. Officer and Witness Testimony
Testimony plays a major role in marijuana DUI cases. Officers often describe the driver’s behavior, smell of cannabis, and performance on field tests. Witnesses—such as passengers or bystanders—may also be questioned to establish when and how the person consumed marijuana before driving.
Why THC Testing Can Be Misleading
Unlike alcohol, THC affects everyone differently and can remain detectable in the bloodstream long after the effects wear off. Regular users might have a baseline THC level above 5 ng/mL even when they aren’t impaired. Because of this, the 5 ng/mL limit is legally treated as a “permissible inference,” not absolute proof of impairment.
Prosecutors usually combine test results with officer observations to argue a case. Defense attorneys often challenge the reliability of blood testing, question the timing of the sample, or present expert witnesses to explain how THC metabolism varies from person to person.
Penalties for Marijuana DUI in Colorado
First Offense
- 5 days to 1 year in jail
- Fines up to $1,000
- License suspension up to 9 months
- Community service between 48 and 96 hours
- Mandatory substance abuse education
Even for a first offense, a conviction will permanently appear on a person’s criminal record. This can impact employment, professional licensing, and future background checks.
Repeat Offenses
- Harsher jail sentences, up to 1 year per offense
- Fines that can reach $1,500
- Two-year license revocation
- Mandatory ignition interlock device upon reinstatement
- Long-term probation and supervised treatment
Repeat DUI convictions are treated more severely, and judges in Colorado typically show little leniency towards offenders who have prior alcohol or drug DUIs on record.
Common Challenges in Marijuana DUI Cases
Defense lawyers in Denver and across Colorado often focus on how evidence was gathered. Field sobriety tests can be affected by medical conditions, fatigue, or environmental factors. Blood samples can degrade if not properly handled, and delays in testing may inflate THC levels. These scientific and procedural issues are often used to create reasonable doubt in court.
Another key question is whether the driver’s abilities were impaired at the time of driving, not simply whether THC was present in the body. Because marijuana affects users differently, proving impairment requires more than a number—it requires credible interpretation of physical and behavioral signs.
Key Details at a Glance
| Aspect | Details |
|---|---|
| Legal THC Limit | 5 nanograms delta-9 THC per milliliter of whole blood |
| Testing Methods | Field sobriety tests, DRE evaluations, blood/saliva/urine analysis |
| Proof Required | Evidence of impaired driving or THC levels above 5 ng/mL |
| First Offense Penalties | 5 days–1 year in jail, up to $1,000 fine, up to 9 months license suspension |
| Repeat Offense Penalties | Longer jail time, up to $1,500 fine, 2-year interlock requirement |
| Refusal of Testing | Administrative license revocation and possible added charges |
Why Legal Representation Matters
Marijuana DUI law brings together both science and legal interpretation. Without skilled representation, defendants may struggle to challenge test results or procedural errors. Experienced DUI lawyers in Denver can review every aspect of the arrest, from the officer’s observations to the chemical testing process, to identify weaknesses in the prosecution’s case.
If you’ve been arrested for a marijuana DUI in Denver or nearby areas such as Aurora, Lakewood, or Arvada, don’t face it alone. A knowledgeable defense team can guide you through Colorado’s complex DUI laws and work to protect your driving privileges and record.
Speak With Smith & Weidinger Today
Smith & Weidinger has extensive experience defending DUI and DUID cases across the Denver metro area. Our legal team understands how THC-based charges differ from alcohol DUIs and how to challenge technical evidence effectively. Contact us today for a confidential consultation and get the support you need to move forward with confidence.