Colorado Marijuana DUI Lawyer

Colorado’s legalization of marijuana didn’t legalize driving under its influence. Prosecutors across the state continue to file DUI Marijuana cases aggressively — often relying on blood-test results showing THC levels at or above 5 nanograms per milliliter of whole blood.

But marijuana affects people differently, and that number doesn’t always mean impairment. Successfully defending a marijuana-related DUI means understanding the science behind THC metabolism — and how to challenge the state’s assumptions.

The Law – C.R.S. § 42-4-1301(6)(a)(IV)

Colorado law creates what’s called a “permissible inference” of impairment:

If a driver’s blood contains 5 ng/mL or more of Delta-9-THC, the jury may infer that the person was under the influence of marijuana.

Importantly, this is not a mandatory presumption. The jury doesn’t have to find guilt based on that number alone — and the defense can present evidence showing that THC levels don’t necessarily correlate with real-world impairment.

Why THC Levels Can Be Misleading

• Tolerance varies. Frequent or medical users often have high residual THC levels even when sober.
• Testing lag. Blood draws may occur an hour or more after driving — long after impairment would have peaked.
• THC storage. Because THC is fat-soluble, it can remain detectable long after use without causing impairment.
• No uniform correlation. Studies show wide variability between nanogram levels and actual driving ability.

These factors make marijuana DUIs among the most scientifically complex cases in Colorado criminal courts.

Penalties for Marijuana DUI in Colorado

The penalties mirror those for alcohol-based DUIs and include:

• Up to 1 year in jail
• Fines up to $1,000
• License suspension upon conviction
• Mandatory drug and alcohol education
• Probation and community service
• Possible ignition interlock requirement if combined with alcohol

A marijuana DUI also counts as a prior for any future DUI or DWAI charges.

How I Defend Marijuana DUI Cases

With over 20 years of experience defending DUI and DUID cases statewide, I use a science-driven approach that includes:

• Retaining a toxicologist to review and interpret blood-test data, including plasma-to-whole-blood conversions and time-delay factors.
• Engaging a police-procedure expert to examine the legality of the stop, the field-sobriety process, and Drug Recognition Evaluator (DRE) protocols.
• Challenging causation — showing that THC presence doesn’t automatically mean impairment at the time of driving.
• Highlighting individual tolerance and medical use that may explain elevated levels without impairment.
• Cross-examining DRE officers on the limits of their training and the absence of validated marijuana-specific testing standards.

When possible, I also work to negotiate reductions or secure dismissals when the evidence doesn’t support the charge.

Call for a Free Consultation

If you’ve been charged with DUI Marijuana in Colorado, act quickly — evidence such as blood-draw timing, video footage, and witness observations can make or break your case.

Call Monte Robbins at 303-355-5148 for a confidential consultation. You’ll speak directly with me — not a junior associate or case screener.