Key Researchers
 

 

Key Results: DUI Policy

Citations Listed in Key Results

  • Lowering the illegal BAC limit from 0.10 to 0.08 has resulted in 5-16% reductions in alcohol-related crashes, fatalities, or injuries in the United States, and saves about 400 lives each year (Fell and Voas, 2006; Shults et al., 2001; Tippetts et al., 2005; Kaplan and Prato, 2007; Wagenaar et al., 2007a).
    A number of high-quality studies have evaluated the effects of lowering the legal BAC limit for driving on alcohol-related traffic crashes. Recently, Fell and Voas (2006) reviewed this literature, focusing particularly on 14 studies of the experiences in the United States. The clear majority of studies show reduction in alcohol-related traffic crashes associated with reduced BAC limits, with effects ranging from 5% to 16%. Shults et al. (2001) also included legally allowable BAC policies as part of their systematic review and found strong evidence for the effectiveness of these laws.

    Two recently published high-quality studies present the most comprehensive evaluations of legally allowable BAC legislation. Tippets et al. (2005) evaluated the effects of lowering the legally allowable BAC from 0.10 to 0.08 g/dl in 19 jurisdictions in the United States. They found significant reductions in drinking-drivers in fatal crashes in 9 of the 19 jurisdictions, with an additional 7 jurisdictions showing reductions that were not statistically significant. Pooling across the 16 states where reductions were observed, they estimated a 15% average reduction in alcohol-related traffic crash fatalities following the change in the legally allowable BAC from 0.10 to 0.08 g/dl.

    Wagenaar et al. (2007a) examined the effects of changes in the legally allowable BAC limit in 28 states from 1976 through 2002 on four measures of alcohol-related traffic crash involvement. They noted considerable variability of effects across states. However, pooled results across states confirmed that changes in legally allowable BAC limit significantly affect the overall burden of fatal crash mortality. They estimated that the move from 0.10 to 0.08 g/dl legal limits in the United States prevents 360 deaths each year. Further, an additional 535 deaths per year would be prevented if the legally allowable BAC limit were lowered from 0.08 to 0.05 g/dl, consistent with legal limits among most countries worldwide. These results were confirmed by Kaplan and Prato (2007). They found an 8% reduction in fatalities associated with lower BAC limits analyzing 22 states, using a different statistical approach than Wagenaar et al.
  • Mandatory jail penalties do not have clearly demonstrable general deterrent or preventive effects (Chaloupka et al., 1993; Legge and Park, 1994; Ruhm, 1996; Sloan and Reilly, 1994; Villaveces et al., 2003; Wagenaar et al., 2007b; Whetten-Goldstein et al., 2000).
    Several high-quality studies have evaluated the effects of mandatory minimum jail penalties for first-time DUI offenders. Outcome measures have included traffic fatalities, DUI recidivism, and others, such as self-reported intention to drink and drive. The highest-quality, most comprehensive studies examine mandatory minimum jail penalties across many states over at least several years. Such studies have consistently found that mandatory jail penalties have no significant effects on overall rates of alcohol-related traffic fatalities.
  • Mandatory fine penalties might have some effects in some jurisdictions, but the evidence is quite weak and equivocal (Chaloupka et al., 1993; Sloan et al., 1994; Wagenaar et al., 2007b; Whetten-Goldstein et al., 2000; Young and Likens, 2000).
    Five comprehensive, high-quality studies have examined effects of mandatory minimum fine penalties for first-time DUI offenders. Outcomes typically include fatal crashes, other non-traffic injuries and mortality, and other measures, such as self-reported intention to drink and drive. Results are inconsistent. Two studies (Sloan et al., 1994; Young and Likens, 2000) show no discernable effects for mandatory minimum fine penalties. In contrast, Chaloupka et al. (1993) noted significant decreases in nighttime and alcohol-related fatalities in their examination across the U.S. states and over time. In their examination of all U.S. states from 1984 to 1995, Whetten-Goldstein et al. (2000) guardedly concluded that mandatory minimum fine penalties for DUI reduced traffic crash fatalities among youth but not adults. Wagenaar et al. (2007b) recently provided the most comprehensive evaluation of mandatory minimum fine penalties, examining effects across 32 states from 1976 through 2002. Excluding states confounded by multiple simultaneous DUI policy changes, they noted a significant reduction of 8% in fatal crash involvement by drivers with BAC of 0.08 g/dl or higher. No significant effects were observed for single-vehicle nighttime fatal traffic crashes or fatal traffic crashes with drivers under the legally allowable BAC limit of 0.08.
  • Pre-conviction immediate administrative driver’s license suspension policies have clearly shown significant effects on alcohol-related fatal crash involvement among drivers at all BAC levels, saving at least 800 lives per year in the United States. Policies that only implement license suspensions post-conviction have no discernable effects (Chaloupka et al., 1993; Legge and Park, 1994; Ruhm, 1996; Voas et al., 2000; Wagenaar and Maldonado-Molina, 2007; Whetten-Goldstein et al., 2000; Young and Likens, 2000).
    These laws require suspension of a driver’s license immediately after a driver fails a breath test (or at most within a day or two). Historic studies of the effects of administrative license suspension penalties frequently find reductions in alcohol-related traffic crashes following implementation. A recent study (Wagenaar and Maldonado-Molina, 2007) examined the effects of implementation of license suspension penalties in every U.S. state between 1976 and 2002. The authors stratified analyses by whether the penalty was applied immediately after the alcohol-impaired driver was detected (i.e., pre-conviction) or later through conviction by the courts (i.e., post-conviction), providing a direct assessment of the principle of celerity - the time elapsed between the offending behavior and the consequence. Results indicated that pre-conviction license suspension penalties significantly reduced alcohol-related traffic crashes by 5%, with similar effects observed among drivers across all levels of intoxication. No effects were observed for post-conviction license suspension penalties.
  • Frequent statewide sobriety checkpoints reduce alcohol-related fatal, injury, and property damage crashes by approximately 20 percent (Elder et al., 2002; Shults et al., 2001; Voas, 2008).
    The Centers for Disease Control and Prevention’s Task Force on Community Preventive Services recently completed a systematic review of policy interventions to reduce alcohol-impaired driving (Elder et al., 2002; Shults et al., 2001). They reviewed 16 studies that examined effects of sobriety checkpoints on alcohol-related traffic crashes. Results from these studies consistently show reductions in alcohol-related fatal, injury, and property damage traffic crashes following implementation of such checkpoints. A recent analysis by Voas (2008) indicates that even relatively small-scale checkpoint operations produce substantial reductions in nighttime car crashes, since the major mechanism of effect is deterring impaired driving across the population, not arresting particular intoxicated drivers.
  • Raising the minimum legal drinking age (MLDA) from 18 to 21 years has reduced alcohol-related traffic crash fatalities from 6 to 30%, despite inconsistent state laws, limited implementation and modest enforcement (Fell et al., 2007; Shults et al., 2001; Wagenaar, 1983; Wagenaar and Toomey, 2002).
    The MLDA is one of the most widely studied alcohol prevention policies. A recent systematic review by the Centers for Disease Control and Prevention’s Task Force on Community Preventive Services identified 46 studies meeting their inclusion criteria of the effects of the MLDA on variety of alcohol-related traffic crash indicators. All of these studies have consistently shown reductions in alcohol-related traffic crashes with increases in the MLDA, with effects ranging from 6% to 30%. A recent study (Fell et al., 2007) contributes to the evidence of the effectiveness of this law, showing a national 11.7% reduction in the ratio of underage drinking drivers to underage non-drinking drivers in fatal crashes following the increases in the MLDA from 18 to 21 years. These results are confirmed by a recent evaluation of New Zealand’s reduction in drinking age from 21 to 18 in 1999, where the youth crash rate increased 12% (Kyrpi et al., 2005). The important health and safety benefits of the age-21 MLDA are now very well established in the scientific literature, documented in an exhaustive review of 132 studies by Wagenaar and Toomey (2002). Follow-up analyses by Carpenter et al. (2007) confirm earlier results of O’Malley and Wagenaar (1991) that a key mechanism of effect of the higher legal drinking age is that the law significantly reduces both the proportion of teens who drink (30-day prevalence) and the proportion who drink heavily (5 or more drinks at a time).
  • So called "zero-tolerance" laws which specify very low or zero legal BAC limits for drivers under age 21 have resulted in declines in driving after drinking and fatal and non-fatal traffic crashes of 4 to 24% (Shults et al., 2001; Wagenaar et al., 2001).
    In their systematic review, the Centers for Disease Control and Prevention’s Task Force for Community Preventive Services identified 11 studies, meeting their inclusion criteria, examining the effects of such "zero-tolerance" laws on alcohol-related traffic crashes. They concluded that zero-tolerance laws reduced fatal and non-fatal traffic crashes by as much as 25%. Moreover, a study of teens in 30 states found a 19% reduction in driving after drinking as a result of laws specifying a zero or very low BAC for young drivers (Wagenaar et al., 2001), and a study of college students found an 11% reduction in driving after drinking (Liang and Huang, 2008). Finally, in addition to the substantial effects specific to driving-after-drinking, Carpenter et al (2007) found that the zero BAC laws reduced overall teen drinking by 4% and heavy drinking by 6%.
  • Graduated driver’s licensing programs reduce young drivers’ crash risk by 20 to 40% (Shope, 2007).
    Shope (2007) recently conducted a review of evaluations of graduated driver licensing (GDL), which establish limits on newly licensed drivers which are gradually lifted (e.g., driving at night, with passengers). She identified 27 studies, 21 of which assessed the effects of GDL within 14 jurisdictions/states across the U.S. and Canada and 6 that assessed GDL nationwide. Effects were consistent, indicating that GDL laws reduce young drivers’ crash risk by 20 to 40%. Recent studies by Zhu et al (2009) (finding a 31% reduction in the driver injury rate among 16-year-olds in New York), Kirley et al. (2008) (finding reduction of 18-37% in various indicators of crashes or injuries in Maryland), and Neyens et al. (2008) (finding similar crash reductions among 16- and 17-year-olds in Iowa) are consistent with the previous literature.

    Strong GDL laws consistently prohibit or highly restrict nighttime driving by younger teens. And several studies have reported significant reductions in nighttime crashes associated with GDL programs (e.g., Cooper et al., 2004; Masten and Hagge, 2003; Shope, 2007; Shope and Molnar, 2004). Since nighttime is also the highest risk time for alcohol-related crashes (Williams et al., 2002), GDL laws are clearly expected to reduce teen alcohol-related crashes. While the research evidence is strong that GDL laws reduce teen car crashes, their effects specifically on alcohol-related crashes have rarely been studied. One exception is Begg et al. (2001), who confirmed that the GDL law in New Zealand resulted in significant reductions specifically in alcohol-related crashes among young drivers.
 
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