Alcohol DUIs and Marijuana DUIs: What is the Difference?

It is common knowledge that driving under the influence of alcohol is illegal and can lead to severe consequences. However, with the growing trend of legalizing recreational use of marijuana and with additional states allowing medicinal use of marijuana, more people are finding themselves facing charges for driving under the influence of marijuana. While both charges are similar, there are also some distinct differences between them that individuals and attorneys need to be aware of.


Both driving under the influence of alcohol (“DUI”) and driving under the influence of drugs (“DUID”) are similar charges in Colorado, as well as in most other jurisdictions across the country. Both of them allege that a driver has been operating a vehicle while under the influence of a substance that impairs the individual’s ability to operate that vehicle. Regardless of the substance, be it alcohol or marijuana, even a small amount can put a person over the limit to safely operate a vehicle. It does not matter whether or not a substance was obtained legally, either. Operating a vehicle under the influence can affect everyone, and consequences can be severe. Consequences for conviction on either charge can include suspension of driving privileges, incarceration, community service, mandatory substance abuse classes, monetary fines, ignition interlock devices, and other penalties depending on the circumstances of the conviction.

Two Distinct Differences

The most notable difference between a DUI and a DUID is in the level of a substance in an individual driver’s blood necessary to demonstrate that a person has been operating a vehicle while impaired by that substance. In Colorado, like most other states, the blood alcohol concentration threshold is 0.08% for DUI and 0.05% for DWAI. When a person’s blood alcohol concentration is at or beyond 0.08%, they are considered to be driving under the influence of alcohol. When a person’s blood alcohol concentration is beyond 0.05% but less than 0.08% it is presumed that the driver is impaired to the slightest degree. Marijuana influence is determined by the presence of tetrahydrocannabinol (“THC”) in an individual’s whole blood. THC is the active ingredient in marijuana that is largely responsible for the “high” individuals feel when using marijuana or marijuana products, and Colorado has capped the THC limit in an individual’s whole blood at 5 nanograms. There is an inference that a driver with 5 or more nanograms of THC in their system is under the influence and cannot safely operate a motor vehicle.

The other distinct difference is in how proof is collected for each particular case. In both cases, Colorado law requires individuals to submit to chemical testing when law enforcement officials have reasonable belief that a person has been operating a vehicle under the influence or while impaired. Refusing to submit to such testing generally results in an automatic suspension of driving privileges along with other consequences regardless of the circumstances. For cases in which driving under the influence of alcohol is alleged, law enforcement officers are required to give the driver a choice of a breath or blood test except in extraordinary circumstances. These officers are also trained and equipped to conduct roadside sobriety tests and preliminary roadside breath tests that can determine whether or not a person is under the influence of alcohol.

For cases involving marijuana, the process is a bit different. In Colorado, law enforcement departments across the state have trained drug recognition experts that are able to assess whether or not an individual is under the influence of a variety of substances including marijuana. If an officer making a traffic stop believes an individual has been operating a vehicle under the influence of marijuana or other drugs and is not a trained drug recognition expert, he or she will usually request one to perform an assessment at the police station. Police will also require the driver submit to a blood test to determine whether or not there is a high enough concentration of THC or other drugs in a person’s blood to put him or her over the limit at which it is safe to operate a vehicle.

Legal Assistance

There is some controversy as to whether or not current testing methods can adequately identify impairment as it relates to marijuana. There are also many nuances in the law regarding charges and related testing for both alcohol and drugs when operating a vehicle that attorneys and individuals must be aware of. It is important to consult with a criminal defense attorney that has experience handling charges for driving under the influence of alcohol and/or driving under the influence of drugs. If you are facing such charges or have questions about what options might be available in defending against them, contact the experienced criminal defense team at Tiftickjian Law Firm to schedule a consultation where you will be able to find out more about your charges and what you might be able to do about them.


Written by Denver DUI Attorney Jay Tiftickjian. Jay Tiftickjian is a trial lawyer, author, and legal analyst.

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