The Uneasy Case for Marijuana as Chemical Impairment Under a Science-Based Jurisprudence of Dangerousness
70 Pages Posted: 15 Feb 2015
Date Written: February 13, 2015
As the marijuana legalization movement lurches forward, states face a jurisprudential dilemma in addressing the burgeoning public health issue of “drugged driving.” Zero-tolerance laws targeting driving with any illegal drug in one’s system, justified under a “jurisprudence of prohibition” based on the blameworthiness of the drug itself, are no longer a good fit. Instead, states have attempted to treat marijuana like alcohol, and have imported drunk driving’s “jurisprudence of dangerousness,” by enacting “per se” driving-under-the-influence-of (DUI) marijuana laws redefining DUI as driving with a certain amount of THC, marijuana’s main psychoactive compound, in one’s blood. These laws are legitimate, we are told, because they are analogous to “per se” .08% blood-alcohol concentration (BAC) impairment laws. What lawmakers have forgotten, and what legal scholars have largely neglected, is the buried and colorful history of drunk driving’s jurisprudence of dangerousness, and the scientific framework established by the country’s first “traffic czar,” William Haddon Jr., for proving the link between specific BACs and crash risk. Under this framework – which focuses first and foremost on fatal single-car crashes and case-control studies with a randomly selected control group – the illegitimacy of the new wave of DUI marijuana laws is painfully obvious. In fact, the few single-car crash and case-control studies that have been conducted have found no relationship between THC blood levels and increased relative risk of crash. Properly understood, the history of drunk driving offers what is still the only valid scientific framework for using the criminal law as an instrument of public safety.
Keywords: marijuana, THC, DUI, alcohol
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