Colorado and Washington state each passed laws allowing the recreational use of marijuana. Eighteen states and the District of Columbia permit medical marijuana. Can you drive with marijuana in your system and avoid a DUI arrest?
You are not allowed to drive after drinking to the point of impairment. Likewise, you are not allowed to drive after using marijuana to the point of impairment. Some states have zero-tolerance laws. The laws vary from state to state.
Effects of Marijuana on Driving
The National Organization for the Reform of Marijuana Laws states: “Although cannabis is said by most experts to be safer than alcohol and many prescription drugs, responsible cannabis consumers never operate motor vehicles in an impaired condition.” http://norml.org/marijuana
Marijuana has been shown to impair performance in driving simulators and driving courses for as long as three hours after ingestion. Impaired factors were vehicle handling, slowed reaction time, estimates of distance, sleepiness and lack of coordination. When marijuana is consumed instead of smoked, it stays in the system longer than three hours. THC metabolites stay in the system much longer than THC itself.
Chronic users, or medical marijuana patients, often perform much better on these tests than occasional users, even with higher amounts of THC in their systems, due to increased tolerance.
How is THC Measured
THC is the active component of marijuana. THC levels are not as easy to measure as alcohol concentrations, which can be measured at the roadside using a breathalyzer. Police use roadside observations, standard field sobriety exercises and drug recognition evaluations to note indicators of impairment. Arrestees in Florida generally submit to urine testing.
So, how much THC in the blood is too much? In many states, “incapacity” or “impairment” observed by an officer that can be directly linked to drug ingestion is sufficient. 15 states have zero tolerance laws. Some of these zero-tolerance states allow use of medical marijuana, which can mean a patient is never allowed to drive. Other states set a per se limit, which allows a user to drive with a certain amount of THC or THC metabolite in his or her blood.
Quite a conundrum.