Since Colorado legalized recreational marijuana, the state has seen an increase in drivers facing DUI charges involving marijuana use. While alcohol and marijuana are both considered impairing substances under state law, the methods used to detect and prosecute each are very different.

At Alfrey & Associates, PC, our Denver criminal defense attorneys have years of experience defending clients charged with both Driving Under the Influence (DUI) and Driving Under the Influence of Drugs (DUID). Understanding these distinctions can make a significant difference in how your case is handled and what defense strategies can be used to protect your freedom.

The Legal Threshold for Marijuana Impairment

For alcohol-related DUIs, the law is clear. A blood alcohol concentration (BAC) of 0.08% or higher is considered per se evidence of intoxication. In contrast, there is no universally accepted “safe” level of THC, the psychoactive compound in marijuana.

Colorado law presumes impairment when a driver’s blood contains 5 nanograms or more of delta-9-tetrahydrocannabinol (THC) per milliliter of blood. However, this is not an absolute standard. Unlike alcohol, THC affects each individual differently depending on frequency of use, metabolism, and tolerance. Regular users can have elevated THC levels long after they are no longer impaired.

This uncertainty makes marijuana DUI cases far more complex—and far more dependent on subjective police interpretation.

How Marijuana DUIs Are Investigated

In an alcohol DUI investigation, officers typically rely on breathalyzer results and standardized field sobriety tests. Marijuana DUIs, however, rely on a different process.

When an officer suspects drug impairment, they may request a Drug Recognition Expert (DRE) evaluation. DREs are specially trained officers who use physical and behavioral observations—such as pupil dilation, pulse rate, and coordination—to determine whether a driver is under the influence of drugs.

If the DRE concludes that drug use is likely, law enforcement will request a blood test. These tests are used to measure THC concentration but are not always accurate. THC can remain in the bloodstream long after impairment has ended, meaning that test results alone may not prove that a driver was impaired at the time of arrest.

Prosecution Challenges in Marijuana DUI Cases

Prosecuting a marijuana DUI is often more difficult than proving an alcohol-related DUI. With alcohol, a clear numerical BAC establishes impairment. For marijuana, prosecutors must rely on a combination of evidence, including:

• Blood test results showing THC levels
• Officer testimony describing driving behavior
• DRE evaluations and field sobriety tests
• Physical evidence such as marijuana or paraphernalia found in the vehicle

Each of these elements is open to challenge. Factors such as inaccurate testing methods, contamination of blood samples, or unreliable officer observations can undermine the prosecution’s case.

Penalties for Marijuana DUIs in Colorado

The penalties for a marijuana DUI are similar to those for an alcohol-related DUI. A first offense can result in:

• Jail time of up to one year
• Fines ranging from $600 to $1,000
• License suspension of up to nine months
• Mandatory drug education or treatment programs
• Community service

Repeat offenses carry significantly harsher penalties, including mandatory jail time, longer license suspensions, and potential felony charges in extreme cases.

A marijuana DUI conviction can also lead to higher insurance rates, difficulty finding employment, and a permanent mark on your criminal record.

Defending Against a Marijuana DUI Charge

At Alfrey & Associates, PC, we understand how to challenge the evidence in marijuana-related DUI cases. Our defense strategies often focus on:

• Questioning the legality of the traffic stop or arrest
• Investigating how blood samples were handled and tested
• Exposing flaws in DRE evaluations or officer observations
• Presenting expert testimony on THC tolerance and impairment levels

Because marijuana impairment is not as easily measured as alcohol, there are many opportunities to create reasonable doubt in your case.

Protect Your Rights with Experienced Defense

If you have been charged with a marijuana DUI or DUID in Colorado, it is important to act quickly. These cases are highly technical, and the evidence can be challenged with the right legal approach.

At Alfrey & Associates, PC, our Denver defense attorneys have extensive experience handling marijuana and drug-related DUI cases. We provide thorough, strategic representation designed to protect your license, your record, and your future.