Marijuana, Alcohol, and Driving: "When compared to alcohol, cannabis is detected far less often in accident-involved drivers. Drummer et al. (2003) cited several studies and found that alcohol was detected in 12.5% to 79% of drivers involved in accidents. With regard to crash risk, a large study conducted by Borkenstein, Crowther, Shumate, Zeil and Zylman (1964) compared BAC in approximately 6,000 accident-involved drivers and 7,600 nonaccident controls.
Marijuana, Alcohol, and Driving: "As with cannabis, alcohol use increased variability in lane position and headway (Casswell, 1979; Ramaekers et al., 2000; Smiley et al., 1981; Stein et al., 1983) but caused faster speeds (Casswell, 1977; Krueger & Vollrath, 2000; Peck et al., 1986; Smiley et al., 1987; Stein et al., 1983). Some studies also showed that alcohol use alone and in combination with cannabis affected visual search behavior (Lamers & Ramaekers, 2001; Moskowitz, Ziedman, & Sharma, 1976).