THC levels don't equal blood alcohol content

The researchers examined the lab results of drivers arrested for impaired driving, finding that the results suggest that legal limits for marijuana and driving are problematic for the following reasons:

- There is no science showing that drivers reliably become impaired at a specific level of marijuana in the blood. Depending on the individual, drivers with relatively high levels of marijuana in their system might not be impaired, while others with low levels may be unsafe behind the wheel. This finding is very different from alcohol, where it is clear that crash risk increases significantly at higher BAC levels.
- High THC levels may drop below legal thresholds before a test is administered to a suspected impaired driver. The average time to collect blood from a suspected driver is often more than two hours because taking a blood sample typically requires a warrant and transport to a facility. Active THC blood levels may decline significantly and could drop below legal limits during that time.
- Marijuana can affect people differently, making it challenging to develop consistent and fair guidelines. For example, frequent users of marijuana can exhibit persistent levels of the drug long after use, while drug levels can decline more rapidly among occasional users.

"There is understandably a strong desire by both lawmakers and the public to create legal limits for marijuana impairment, in the same manner as we do with alcohol," said Marshall Doney, AAA's president and CEO. "In the case of marijuana, this approach is flawed and not supported by scientific research. It's simply not possible today to determine whether a driver is impaired based solely on the amount of the drug in their body."

Special Reports /

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