The primary area of developing law for most patients to consider is Driving Under the Influence of Drugs or DUID. In 2011, the Colorado Legislature considered setting a per se limit of 0.05 nanograms of THC per liter of blood. This would have meant that persons found with a higher limit could have been prosecuted much as defendants in Driving Under the Influence of alcohol are today, when their blood-alcohol tests at above 0.05, or 0.08.

Though the legislature failed to pass such a pro se, law, there has been an elevated number of prosecutions for DUID cases involving marijuana. Without the pro se law, such cases are more difficult to prosecute, necessitating the use of expert witnesses to prove a level of intoxication. But prosecutors are willing to press more of these cases. In any regard, being a registered marijuana patient does not allow people to drive under THC intoxication.

However, Mr. Grossman advises that because there are no established limits for the amount of THC in the blood defining intoxication, most first-time defendants should probably not refuse a test if demanded by police. Refusal would cost the defendant their license for a year, and the level of intoxication is an element always argued in court.