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Driving while stoned is illegal in all 50 states, but not all DUI laws are the same. Colorado’s drug-related driving laws are a bit different than most other places in the country, making it more likely that drivers can reduce or beat marijuana DUI charges. Here in the Centennial State, we use a system called “permissive inference.” If a driver tests above five nanograms of THC, the active chemical in cannabis, per millimeter of blood, authorities are only allowed to infer that the driver was under the influence of marijuana; it is not a guaranteed charge. Our system works this way because marijuana tends to stick around in the body’s fat cells for a long period of time, sometimes as long as three months. A blood test showing THC does not necessarily mean that the driver was impaired at the time of the testing. Watch Attorney Jake Johnson goes into detail about why marijuana DUI allegations can be beaten in this video: There are 11 states where any amount of THC in a driver’s blood is grounds for arrest. These are the zero tolerance states. These laws are problematic for longtime pot partakers, medical marijuana patients or just the average joe who took a hit off his friend’s joint during a weekend BBQ. Because THC stays in the system so long, a driver in any of these 11 states could be arrested for impaired driving even if they had not smoked in weeksand were not under the influence when they were behind the wheel! More than a dozen states have what are called “per se” marijuana DUI laws (the favored law by the White House.) If a driver’s THC test shows levels above the state’s legal limit, the driver can be handed a DUI conviction without further inquiry; in many of these per se states, the legal limit is zero. These laws, like zero tolerance laws, do not take into account fat cell retention of THC and do not require evidence of impairment. All in all, Colorado’s method of dealing with the issue of drug-related driving is more reflective of the science behind marijuana than other states’ policies—but there is still room for improvement in our DUI laws. Utilizing permissive inference helps protect drivers who smoke but do not drive impaired. Thomas Law Firm – Marijuana DUI Attorneys Source:

How are Colorado’s Marijuana DUI Laws Different from Other States?

Driving under the influence of marijuana is illegal in all 50 states. Still, the specific laws and regulations regarding marijuana-related DUI charges can vary significantly from one state to another. Colorado, often at the forefront of marijuana legislation due to its early legalization of recreational cannabis use, has unique drug-related driving laws that set it apart from most other states in the U.S. These laws are designed to address the complexities of marijuana’s effects on the body and aim to ensure fair treatment for drivers who may have consumed marijuana but are not necessarily impaired.

In Colorado, the approach to marijuana-related DUI charges differs due to the utilization of a system known as “permissive inference.” Under this system, if a driver tests above a threshold of five nanograms of THC (the active chemical in cannabis) per milliliter of blood, authorities are allowed to infer that the driver was under the influence of marijuana. However, it is crucial to understand that this inference is not an automatic or guaranteed charge of DUI. This distinction is essential because marijuana can remain in a person’s fat cells for an extended period, sometimes up to three months. Therefore, a positive blood test for THC does not necessarily imply impairment at the time of testing.

It’s important to note that Colorado’s approach is rooted in a consideration of the science behind marijuana’s effects on the body. Unlike some other states, where any detectable amount of THC in a driver’s blood can lead to an arrest (referred to as “zero tolerance” states), Colorado’s system allows for a more nuanced assessment. This approach recognizes that individuals who have consumed marijuana may still be capable of safe and responsible driving, provided that they are not impaired.

Zero tolerance states, on the other hand, present challenges for various individuals, including longtime marijuana users, medical marijuana patients, and even those who may have taken an occasional hit at a social gathering. In these states, the presence of any THC in a driver’s blood can lead to an arrest for impaired driving, irrespective of when the marijuana was consumed or the individual’s state of impairment at the time of driving.

Additionally, several states have adopted “per se” marijuana DUI laws, which the White House favors. Under these laws, if a driver’s THC test results exceed the state’s legal limit, they can be convicted of DUI without the need for further inquiry. In many per se states, the legal limit is set at zero, meaning that any detectable amount of THC can lead to a DUI conviction. These laws, similar to zero-tolerance laws, do not account for the retention of THC in fat cells or require evidence of impairment.

While Colorado’s approach to drug-related driving is generally more reflective of the scientific understanding of marijuana’s effects, there is still room for improvement in the state’s DUI laws. The use of permissive inference helps protect drivers who have consumed marijuana but are not impaired. However, ongoing efforts to refine and adapt these laws to align with evolving scientific research and public safety concerns are essential.

Thomas & Ahnell, LLC, is a law firm specializing in alcohol and drug-related driving offenses in Colorado. Their team of experienced DUI attorneys is well-versed in the intricacies of Colorado’s unique DUI laws, including those related to marijuana. In a rapidly changing legal landscape, having a trusted legal partner is crucial to navigating the complexities and ensuring fair treatment for individuals facing DUI charges.


In conclusion, Colorado’s approach to marijuana-related DUI charges sets it apart from many other states, emphasizing a nuanced understanding of marijuana’s effects and impairment. While the state’s permissive inference system provides some protection for individuals who have consumed marijuana without impairment, there remains room for improvement and continued adaptation of these laws to align with scientific knowledge and public safety concerns. Legal guidance from experienced attorneys, such as those at Thomas & Ahnell, LLC, is invaluable for individuals facing marijuana-related DUI charges in Colorado.

Do you have further questions or concerns? Call us or contact the attorneys at Thomas & Ahnell, LLC, and we will be happy to help.

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