How Long Does Marijuana Stay in Your System for DUI Testing in Colorado?

As marijuana use becomes more common in Colorado, so do questions about how it affects driving and what happens if you’re pulled over after consuming cannabis. Many drivers are surprised to learn that even if they aren’t high, they can still face a marijuana DUI charge because THC stays in the body long after the effects wear off. Understanding how long marijuana remains in your system and how Colorado tests for impairment can help you protect your rights if you’re ever stopped by police.

Colorado’s Marijuana DUI Laws Explained

Under Colorado law, it’s illegal to drive while “under the influence” of marijuana, even if the cannabis was obtained and used legally. The law establishes a permissible inference of impairment at 5 nanograms of active THC per milliliter of blood. That means if your blood test shows this level or higher, a prosecutor can argue that you were impaired. However, this doesn’t automatically mean you’re guilty; THC affects everyone differently, and your defense attorney can challenge whether you were truly impaired at the time you were driving.

Unlike alcohol, where the body processes ethanol at a predictable rate, THC behaves differently. It’s fat-soluble, meaning it binds to fatty tissues and releases slowly over time. That makes it difficult to link a blood test result directly to impairment, especially for frequent users.

How Long THC Stays in Your Body

There’s no one-size-fits-all answer to how long marijuana stays in your system. The duration depends on several factors, including how often you use it, your metabolism, body fat percentage, and the potency of the product. Here’s a general timeline:

• Occasional users (once or twice a week): THC may remain detectable in the blood for 1–3 days.
• Regular users (several times a week): THC can linger in the blood for 7–10 days after use.
• Heavy or daily users: THC and its metabolites may be detectable for up to 30 days or longer.

These estimates refer to the presence of THC in your system, not necessarily to impairment. The psychoactive effects of marijuana typically last only a few hours, but chemical traces remain much longer. This disconnect between presence and impairment is one of the major problems with how Colorado enforces marijuana DUI laws.

How Police Test for Marijuana Impairment

When a driver is suspected of being under the influence of marijuana, law enforcement officers may conduct a series of evaluations to determine impairment. These usually include:

• Field sobriety tests (FSTs): Designed to assess balance, coordination, and attention. However, these tests were developed for alcohol impairment and can be unreliable for cannabis.
• Drug recognition evaluation (DRE): A certified officer performs a multi-step assessment, checking vital signs, pupil size, and other indicators.
• Blood tests: The most common way to measure THC levels in Colorado DUI cases.

It’s important to know that blood tests detect the active THC currently circulating in your system, but they cannot determine when you consumed marijuana or whether you were actually impaired while driving. For frequent users, residual THC can result in test results that exceed 5 nanograms even when sober.

Why Marijuana Blood Tests Can Be Misleading

One of the biggest issues with marijuana DUI enforcement is that the science behind THC impairment isn’t as clear-cut as it is for alcohol. A person who uses cannabis regularly might have a higher baseline THC level without being impaired, while someone who rarely uses might show impairment with lower levels.

Additionally, testing methods have inherent flaws. Blood samples can degrade over time, and handling or storage errors can affect accuracy. Prosecutors often rely heavily on blood test results, but these tests don’t always paint a fair picture of what happened on the road.

An experienced DUI defense attorney can challenge the reliability of the test and the validity of the traffic stop. Factors such as medical marijuana use, chronic pain treatment, or the presence of legal THC products can all complicate how your results should be interpreted.

Defending Against a Marijuana DUI Charge in Colorado

If you’ve been arrested for a marijuana-related DUI, it’s crucial to act quickly. A conviction can carry severe penalties, including license suspension, fines, and possible jail time. Fortunately, you have the right to challenge the evidence against you.

Common defense strategies include:

• Questioning the accuracy of the blood test or the chain of custody for your sample.
• Arguing that your THC level was elevated due to residual presence, not impairment.
• Highlighting procedural errors by law enforcement during the stop or testing process.
• Demonstrating that medical marijuana use led to false assumptions of impairment.

Because marijuana DUI law remains a developing area in Colorado, courts continue to grapple with how to apply scientific evidence fairly. Having a lawyer who understands both the legal and scientific aspects of THC testing can make all the difference in your case.

Speak With a Colorado Marijuana DUI Defense Attorney

THC can stay in your system for days or even weeks, but that doesn’t automatically mean you were impaired behind the wheel. If you’re facing marijuana DUI charges, it’s essential to get legal help immediately. At the Law Office of James Colgan, we know how to challenge unreliable testing and fight for your rights in court. Our firm has extensive experience defending drivers across Colorado in complex DUI cases.

Don’t let a marijuana DUI charge define your future. Contact us today to schedule a free consultation and discuss your case. We’ll review the evidence, explain your options, and work to achieve the best possible outcome for you.