Currently a BAC of 80 milligrams (mg) in 100 milliliters of blood constitutes irrefutable evidence that an indictable motor vehicle offense has been committed. Experimental and epidemiologic evidence indicates that BAC's between 50mg and 80mg do not so adversely affect driving-related skills as to constitute impairment of ability to drive in many groups of drivers and are not strongly associated with increased risk of accident involvement except for some groups of drivers. As a result, it is recommended that the current BAC limit of 80mg not be lowered to extend to the marginally impaired and drivers at relatively low risk of accident involvement. As to the implementation of a two-tiered system linking higher BAC to more severe penalties, scientific evidence likewise provides little support. While higher levels of impairment and greater risk of accident involvement may be associated with higher BAC (e.g., above 150mg), there is great individual variability in responses to alcohol, and factors and characteristics other than BAC influence the relationship between BAC and relative risk of accident. It is suggested that combined chemical and behavioral evidence offers a more reliable and realistic basis for judging the degree of driving impairment in any one case. Possible revisions in other sections of the Criminal Code are suggested to facilitate more effective screening and sanctioning of the high-risk, problem-drinker offender. Approximately 130 references.