The news has recently been abuzz about the wisdom, or not, of criminalizing a person’s driving with a specific THC (marijuana’s main active ingredient) blood level.

Alec Siegel at Law Street Media says that “drivers in Montana, Washington, Pennsylvania, Ohio, Nevada, and Colorado are convicted of a DUI if they are found with a certain amount of a cannabinoid–THC, hydroxy-THC or carboy-THC–in their bloodstream.” Similarly, East Bay Times says “In 12 states, driving with any trace of marijuana in the body is a criminal offense, and in five others, the presence of a designated amount of marijuana’s active ingredient in a driver’s blood triggers an automatic conviction.”

Recenctly in Michigan, the “House voted 107-1 … on a bill to create a commission to research and recommend a threshold of THC bodily content that would constitute evidence of impaired driving.”

It was bad enough that 2000 federal highway legislation shoved mandatory criminalization of driving with a 0.08 blood alcohol level down the states’ throats under the penalty of otherwise losing federal highway funding. Now we have a slippery slope of governments trying to criminalize threshold THC levels as well. The whole effort is oversimplification of police, prosecution and judicial work at the expense of those whose driving is simply not made dangerous by a mere threshold level of alcohol or THC in their bloodstream.

As a forensic toxicologist I work with confirms, blood THC levels cannot correlate with any driving impairment. For starters, THC remains in one’s bloodstream for weeks, and marijuana smoked two weeks ago clearly is not going to impair one’s driving today.

Although the hardly liberal American Automobile Association claims that fatal “crashes involving drivers who recently used marijuana doubled in Washington after the state legalized the drug,” AAA also acknowledges and links to studies supporting that legal “limits, also known as per se limits, for marijuana and driving are arbitrary and unsupported by science.”

In 1993, the United States Department of Transportation acknowledged that “[a]vailable evidence leads to the conclusion that it is usually impossible to predict the psychological effects of THC from its determination in a single plasma sample.” “Marijuana and Actual Driving Performance” at 2 (DOT).  Subsequently, the DOT through the National Highway Safety Transportation Administration says: “It is difficult to establish a relationship between a person’s THC blood or plasma concentration and performance impairing effects.” (Thanks to Paul Armentano for his article and links on this subject.)

The United States has become an over criminalized society that is a far cry from the ideals of life, liberty and the pursuit of happiness expounded jpon in the Declaration of Independence. If we do not make life more of a matter of caveat emptor/buyer beware rather than passing law after law to try to insulate people from others’ actions, we will continue to pay for it with the police-nanny state that we currently have.