THC and Taking the Wheel
With the legalization of recreational marijuana, driving while impaired quickly became an overwhelming concern for entire states, not just the users of marijuana. Unlike other issues that only impact the actual users—pricing, where to ingest, accessibility—driving under the influence is simply dangerous for everyone. How is this measured though? How can a marijuana user, medical or recreational, be responsible?
While there are current laws in place, stipulations for being impaired and how to measure impairment are still being worked on. Much like the legality of marijuana, consequences and metrics vary state-to-state.
When pulled over for suspicion of driving under the influence of marijuana, testing is a bit of a problem, unlike testing for alcohol. Currently, the only reliable test is a blood screening because recently ingested marijuana doesn’t immediately appear in urine.
While there are companies developing marijuana breathalyzers, which will measure the active THC in a driver, none are quite ready. Cannabix Technologies is a company that has a model currently in alpha testing, and devices like this aim to represent the current state of the suspect more accurately than a blood test. Additionally, it would be significantly cheaper than blood testing.
The generally accepted level of THC in the bloodstream is 5 nanograms per milliliter of blood (ng/m). It is after 5ng/m that the THC content in the blood seems to indicate that drivers are impaired to the point of a higher accident risk than a sober driver.
The issue for law enforcement is determining whether or not the driver is impaired. Once alcohol is ruled out, suspicion of marijuana impairment is typically a judgment call.
Colorado’s laws are much more lenient when compared to Washington’s. Colorado has what is called a permissive inference law. This means that while blood THC levels may yield a test result more than the legal limit of 5ng/m, it is not immediately assumed the driver is guilty of a DUI.
In Washington, a “per se” limit is in place. What this means is that if the person tests over the legal limit (also 5mg/m) a driver can be immediately charged with a DUI, whether or not physical signs of impairment are present.
This presents a potential problem because the measurement of THC in the blood stream is, for lack of a better phrase, not an exact science. The standard of 5ng/m was established as a guideline, as there is evidence that supports impairment begins after this number. However, the level in the blood stream is highly dependent on many factors, such as how THC was ingested, how long since ingestion and how often the user actually partakes in the substance. For example, in a controlled test, six of 25 heavy users contained active levels of THC in their blood after a week of abstaining, the highest being 3ng/m.
Blood or urine tests simply detect the current amount of THC metabolites in the system, not necessarily current level of impairment. It is for this reason that per se limits that exist in states like Washington could potentially charge a sober person with a DUI.
This is the largest difference between marijuana and alcohol, two drugs whose parallels are increasingly contrasted. Unlike THC, alcohol DUIs are an easy thing to evaluate and measure, between the legally recognized blood alcohol content of .08 percent, agreed upon by all states, field sobriety tests and breathalyzer tests.
As laws change and adapt, the most important thing to stress is personal responsibility. Like doctor sanctioned prescriptions or alcohol, THC products are an impairing drug and should be treated as such, with respect and mindfulness not just for yourself, but for the world around you.