Complex as alcohol and drunk driving issues are, they can seem simple compared with the challenges that marijuana poses to the legal system. A recent Arizona Court of Appeals decision highlights just how different the two drugs are.
In December the court ruled that medical marijuana patients arrested for driving under the influence of cannabis can contest DUI charges by claiming that they were not too high to operate a vehicle.
It’s a can of worms all right: unlike drivers arrested for being under the influence of booze, those driving with marijuana in their systems who have a medical excuse can claim that they were not impaired to drive. The burden of proving impairment will be on the prosecution.
A breathalyzer gives objective of the amount of alcohol in a person’s system, and that amount has been correlated to impairment. It’s generally agreed that a person with a blood alcohol concentration (BAC) of .08 is too impaired to drive.
No such standard of impairment exists for marijuana yet. Moreover, the drug will stay in the system for days after impairment has vanished, making it difficult to use blood tests for evidence. While no one seriously disputes that pot can make a driver dangerous, it’s been hard establishing links between amounts consumed and impairment. For one thing, pot can be eaten or smoked, which can affect a person differently. Even if the amount taken in is measured carefully, the amount of THC (tetrahydrocannabinol, marijuana’s active ingredient) in the blood is hard to correlate to a specific degree of impairment.
Another complication is that marijuana is prescribed by doctors for a number of conditions. On its own that is no excuse for a DUI: you can be arrested for driving under the influence of any prescription drugs which affects your driving ability. But the increasing availability and medical use of marijuana, combined with legal uncertainty of how to prosecute, will doubtless cause confusion in the courts.
What we end up with is a can of worms – complicated cases, dismissals, appeals, and law enforcement officers who are unsure of how to proceed because cases involving driving with marijuana in one’s system are getting thrown out right and left. Eventually it will all be worked out, but not for a while. Meanwhile, Arizona and other states will have to feel their way forward and try to keep the roads safe somehow.