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Effectiveness: 3 Star Cost: $
Use: Unknown
Time: Short

Zero-tolerance laws set a maximum BAC of less than .02 g/dL for drivers under 21 years old. Violators have their driver’s licenses suspended or revoked. There is strong evidence that zero-tolerance laws reduce alcohol-related crashes and injuries (Voas & Lacey, 2011; Goodwin et al., 2005; Shults et al., 2001). Fell et al. (2009) estimate that zero-tolerance laws save 159 lives each year.

However, enforcement and publicity for zero-tolerance laws appears to be rare (Hedlund et al., 2001; Voas & Lacey, 2011). Studies have found that young drivers are not arrested in proportion to their involvement in alcohol-related crashes (Hingson et al., 2004). One exception is Washington State, where a study found that arrests for alcohol violations among 16- to 20-year-old drivers increased by about 50% after the zero-tolerance law went into effect (McCartt et al., 2007). Enforcement may have been greater in Washington because the law allows officers to request a test for alcohol based on suspicion of either a DWI or zero-tolerance offense. In other States where drivers can only be tested if DWI is suspected, zero-tolerance laws may be more difficult to enforce.


Zero-tolerance laws have been in effect in all States since 1998. The degree to which zero-tolerance laws are enforced in States is unknown.


An early study in Maryland found that alcohol-involved crashes for drivers under 21 dropped by 21% in six counties after the zero-tolerance law was implemented. After the law was publicized extensively, these crashes dropped by an additional 30% (Blomberg, 1992). No other studies have examined the effect of increasing enforcement and publicity for an existing zero-tolerance law. Lacey et al. (2000) documented how zero-tolerance laws are administered and enforced in 4 States. Highly publicized enforcement has proven effective in increasing compliance with many traffic safety laws and reducing crashes and injuries: see for example countermeasure on publicized sobriety checkpoints and Short-Term, High-Visibility Seat Belt Law Enforcement. A review of the impact of impaired-driving laws on alcohol-related fatalities from 1980 to 2009 found the zero-tolerance law to have the most impact with an estimate of 19 to 29 lives saved in 2012 (Ying et al., 2013). The study also found that areas with historically high impaired-driving fatalities may need ex-post regulations, such as the zero-tolerance and other penalizing laws, to reverse the trend. This contrasts with other locations that can show improvements with preventative regulations such as the MLDA and open container laws.


Zero-tolerance laws can be enforced during regular patrols or during special patrols directed at times and areas when young, impaired drivers may be present. Enforcement will require moderate costs for appropriate training, publicity, and perhaps equipment (see Other considerations).

Time to implement:

Enforcement programs can be implemented within 3 or 4 months, as soon as appropriate training, publicity, and equipment are in place.

Other considerations:

  • Zero-tolerance-law provisions: Zero-tolerance laws are far easier to enforce if the offense is an administrative rather than criminal violation as an administrative license suspension can be implemented without a court conviction, and if law enforcement officers can use PBTs (preliminary breath test devices) at the roadside to determine if the law has been violated and, if so, to seize the driver’s license (Jones & Lacey, 2001). Some State laws require the same probable cause as for a standard DWI arrest, or even require a full DWI arrest, before a BAC test for a zero-tolerance-law violation can be administered. In these States, the zero-tolerance law is not enforced independently of the standard DWI law, and in fact young drivers may not be aware of the zero-tolerance law (Hingson et al., 2004).
  • PBT and PAS: Preliminary breath test devices are important for effective and efficient enforcement in States that allow PBT use for zero-tolerance laws. A passive alcohol sensor (PAS) can help officers detect violators who have consumed alcohol. See countermeasures Alcohol Measurement Devices.
  • Holding juveniles in custody: A complication of enforcing zero-tolerance laws is issues related to holding young offenders once they are taken into custody. NHTSA helped produce an implementation guide for developing a juvenile holdover program (NHTSA, 2001).