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Marijuana DUI

As of January, 2014, residents of Colorado that are 21 years of age or older are allowed to purchase up to one ounce of Marijuana. Visitors from out of state are allowed to purchase up to one-quarter ounce. Residents are also allowed to grow up to six marijuana plants. Colorado's Driving Under the Influence laws have evolved to make it possible to prosecute Marijuana DUI cases.


Denver police will now be asking those suspected of driving under the influence of marijuana to submit to take a blood test, as there is no breath test for the presence of marijuana in the blood. The legal limit has been set at 5 nanograms of THC in the blood of the driving suspect. A blood level of 5 nanograms of THC or higher does not constitute “DUI Per Se,” meaning that such a test result does not automatically mean a jury should reach a guilty verdict. The defendant has the right to rebut this conclusion, and offer evidence that that there was no impaired driving as a result of marijuana consumption. However, the prosecution has the advantage of their being a presumption of guilt with a test result of 5 nanograms or higher.

This has set the stage for complicated legal battles around what most experts would agree is a fictitious blood THC limit. The Colorado State Legislature would like to make the prosecution of these offenses black and white, as with alcohol cases. The problem with this approach is that marijuana and alcohol act very differently in a person's body. Alcohol increases in the blood stream when it is consumed, then disappears relatively quickly from the blood stream – in a manner consistent with the impairment effects of alcohol. In other words, when the blood alcohol level decreases, the impairment effects decrease with it. Marijuana is precisely the opposite. After consuming marijuana, the blood level of THC increases, but the person's blood will test positive for elevated levels long after the impairment effects have worn off. In fact, for regular pot users, they would test at elevated levels long after any psychoactive effects of the drug have worn off – even days or weeks later.

THC, the active ingredient in marijuana, is a fat-soluble substance. For this reason, it is not excreted from the body very quickly. It remains dissolved in the fatty tissues of the human body, and blood, for an extended period of time. This is why drug tests for THC can show positive results for weeks after the person last used the drug. Conversely, alcohol levels will reach zero, usually within several hours of use, depending on the amount that was consumed.

Driving tests have shown that regular marijuana users that tested with 15 nanograms of THC in their blood, three times the legal driving limit, had no trouble driving whatsoever. Yet, when a marijuana DUI case now goes to trial, the defendant will face an unfair “presumption” of guilt based on a blood test result that has no actual meaning. The defendant will likely testify that they are regular pot users, to explain why they had elevated blood THC levels, yet were not under the influence at the time they were arrested. The use of expert witnesses has become essential in order to educate juries that the blood limit of 5 nanograms has no meaning in a case where the defendant regularly uses marijuana.

With recreational use of marijuana now being legal for anyone over 21, many members of the population will have a blood level over 5 nanograms days or even weeks after their last use of the drug. This can lead to terrible results for the legal system. For example, imagine an auto accident where death results, and the driver that survives produces a positive blood test. The driver may be presumed to be under the influence, which supports the charge of vehicular homicide, even in cases where the driver was not at all impaired by drugs. The defendant will have to defend against this unfair presumption in order to avoid a lengthy prison term for being wrongfully convicted of vehicular homicide.

Driving Under the Influence charges have always involved very complicated evidence. The legalization of the recreational use of marijuana, along with the passage of the misleading 5 nanogram blood limit, has added a new layer of complication to the defense of these cases. It is more important than ever to have expert legal help if you are facing these charges.

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