A Colorado law that went info effect in 2013 permits a judge or jury to infer that a motorist was driving under the influence of marijuana if a test of their blood reveals a level of five nanograms of THC per milliliter of blood in the driver’s system at or around the time of the stop by law enforcement.

However, unlike .08 legal limit for DUIs involving alchol, a judge or jury is not required to find that a motorist driving with a THC level of 5 ng/ml or more was “under the influence” as a matter of law.  Instead, the trier of fact may consider other evidence, such as the scientifc reliability of the 5 ng/ml threshold as an indicator of impairment, or the fact that driver was a medical marijuana cardholder, in deciding whether a motorist is guilty or not guiltly of DUID.

Prior to the five-nanogram inference, prosecutors and police still utilized blood tests to attempt to prove the amount of THC — an active ingredient in marijuana — that a person had in his or her blood when he or she was driving, or shortly thereafter. If the proper evidentiary foundation was presented by the prosecutor in court, the blood test results for a driver were admitted as evidence at trial for the jursy to consider. It was then up to the prosecution to convince the judge or jury as to what the result signified, i.e. did the test result, along with the other evidence, show beyond a reasonable doubt that the defendant operated a motor vehicle while impaired by THC?

Today a jury may convict somebody of driving under the influence of marijuana if their blood test result shows that the driver had at least 5 ng/ml of THC in their system at or around the time of driving. No further evidence about the significance of the blood test is necessary for a driver to be convicted of DUID.

This is problematic. While this legal limit was established taking into consideration some scientific research, there is equal if not greater research showing that the 5 ng/ml limit is not indicative of impariment from marijuana use.

A person convicted of DUID for marijuana use in Colorado faces the same harsh penalities as someone convicted DUI for alcohol use.  A skilled criminal defense attorney, like Brian Boal, can present evidence in the form of expert testimony to a jury that the five nanogram limit is actually an arbitrary threshold that is not necessarily indicative of impariement, in addition to utilizing other, more traditional lines of cross examination and evidence presentation, i.e., showing that a blood test result is possibly inaccurate due to contamination or improper administration of the test.   These, as well as many other strategies, are fair game for a defense attorney defending an individual charged with DUID for marijuana use.

Source: hightimes.com, “The Fallacies of Colorado’s DUI-D Laws“, Jay Tiftickjian, Sept. 19, 2016

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