A study by AAA’s safety foundation found that driving under the influence of marijuana laws in the U.S. are not based on scientific research. Instead, researchers determined that the traditional method – testing for THC in the bloodstream – is not an adequate way of testing for impairment.
According to the study, drivers with low levels of THC content in their blood can still be unsafe, while others with high levels might not be as dangerous, according to the RT report.
Researchers found that people with high THC levels in their blood were sometimes safer drivers than those with lower concentrations. The blood-alcohol-content limit for alcohol-related DUI impairment is .08 percent. Three of the six states with marijuana-DUI benchmarks, Colorado, Washington and Montana, set the BAC marker for marijuana-DUIs at 5 nanograms per milliliter of blood, but cannabis is not metabolized by the body the same way as alcohol, and the presence of THC, high or low, is often not a true indicator of how impaired a driver may, or may not, be.
Some regular cannabis users might always exhibit higher continuous THC levels and might not be under the influence at all when their blood is taken for DUI suspicion – but the test would indicate otherwise. On the flip side, a moderate cannabis user might have very low proportions of THC in their blood but could still be under the influence. Those users might also be more impaired by a small amount of marijuana compared to regular users.
“It’s an attempt to try to do an apples-to-apples comparison with blood alcohol concentration,” Marijuana Policy Project senior legislative analyst Chris Lindsey said.
AAA recommended that police officers be trained in spotting signs of impairment, such as field sobriety tests, rather than relying on BAC testing.
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