Citation

Rast P. Collision 2009; 4(1): 80-87.

Copyright

(Copyright © 2009, Collision Publishing)

DOI

unavailable

PMID

unavailable

Abstract

While the relationships between blood alcohol content (BAC), driving ability and collision risk are well established, researchers have not stated explicitly that alcohol causes collisions. Instead, causality is inferred by correlating BAC to collision frequency and risk. Most courts do not allow statistical evidence in criminal cases and so would be expected generally to disallow collision risk ratio versus BAC evidence as proof that alcohol causes collisions. However, the California Highway Patrol's Collision Investigation Manual (CIM) protocols mandate that alcohol be elevated to the sine quo non ("but for") collision cause in alcohol-related collisions. Contrary to standard forensic practice, the CIM requires that when the at-fault driver in a collision is determined to be under the influence of alcohol, an alcohol-related vehicle code violation is to be identified as the primary collision factor, regardless of the factual "but for" collision cause. The author of this paper argues that there is no empirical justification for this mandate. Transforming correlation into causation through protocols such as that found in the CIM effectively subverts courts' traditional reluctance to accept probability evidence in criminal court proceedings. In addition, the criminal charges and convictions resulting from this mandate are relatively more severe, and possibly judicially inequitable, than if the mandate had not been imposed.