Blood Alcohol Concentration (BAC) Limits: Adult Operators of Noncommercial Motor Vehicles

(Period Covered: 1/1/1998 through 1/1/2012)

This policy topic covers laws addressing blood alcohol concentration limits applicable to drivers of noncommercial automobiles, trucks, and motorcycles who have reached the legal drinking age of 21 years.  

Blood alcohol concentration (BAC) is a measure of the amount of alcohol in a person's bloodstream. BAC is commonly expressed in percentage terms. For instance, having a BAC of 0.08 percent means that a person has eight parts alcohol per 10,000 parts blood in the body. State laws generally specify BAC levels in terms of grams of alcohol per 100 milliliters of blood (often abbreviated as grams per deciliter, or g/dL). BAC levels can be detected by breath, blood, or urine tests. The laws of each jurisdiction specify the preferred or required types of tests used for measurement.

BAC statutes establish criteria for determining when an operator of a vehicle is violating the law. This section provides information on State and Federal BAC laws that apply to drivers of noncommercial automobiles, trucks, and motorcycles who have reached the legal drinking age (21 years).

All jurisdictions have enacted per se BAC laws for adults operating noncommercial motor vehicles. A per se BAC statute establishes a BAC limit for a violation. If the operator has a BAC level at or above the per se limit, a violation has occurred without regard to other evidence of intoxication or sobriety. In other words, exceeding the BAC limit established in a per se statute is itself a violation. By limiting the use of evidence by defendants, per se laws make conviction more likely. [1].

In the past, some States without a per se law established other standards for using BAC levels as evidence of being under the influence of alcohol. In these jurisdictions, the weight given to the BAC evidence varied. Some laws provided that a BAC at or above a particular level created a presumption of being under the influence of alcohol. Other laws provided that such evidence was prima facie evidence of being under the influence, or was admissible in making this determination. These evidentiary standards were even weaker than a presumption. Defendants in jurisdictions without a per se standard could provide evidence that, in spite of the BAC level, they were not under the influence and therefore not in violation. This differentiates other statutes from per se statutes, which provide that exceeding the BAC limit is itself a violation and only the validity of the BAC measurement is at issue.

For historical data, APIS distinguishes between per se and non-per se jurisdictions but does not distinguish the evidentiary weight of BAC evidence in jurisdictions without a per se standard.

[1] Cowan, J. and Joffie, S. "Proof and disproof of alcohol-induced driving impairment through blood alcohol testing," 4 Am. Jur. POF 3d 229 (July 2002)

Explanatory Notes and Limitations Specifically Applicable to Blood Alcohol Concentration Limits: Adult Operators of Noncommercial Motor Vehicles 

1. This review examines only the specific BAC laws for drivers of noncommercial motor vehicles in each State and the District of Columbia and the specific Federal legislation cited. 
    
2. This review does not address the following issues related to BAC limit laws:
    
   • Penalties for violations of BAC laws.
   • State and Federal laws related to enforcement of BAC laws.
   • Provisions covering enhanced sanctions for violators whose BAC exceeds a specified level that is higher than the legal limit (e.g., BAC > 0.20 g/dL).
   • Provisions related to repeat offenders.
   • Provisions that create a rebuttable presumption of impairment or other evidentiary standards at lower levels of BAC than the per se limits.
   • BAC limits that apply to operators of commercial motor vehicles.
   • Laws that may pertain to BAC limits for those who operate nonmotorized bicycles.
   • Separate laws for Indian Reservations. Approximately 200 tribes across the Nation have jurisdiction and responsibility for laws affecting their reservations. Many have passed their own BAC laws.
   • BAC limits applicable specifically to persons who have not yet attained the legal drinking age (21 years of age). See related policy topic BAC: Youth.
      

Explanatory Notes and Limitations Applicable to All APIS Policy Topics

1. State law may permit local jurisdictions to impose requirements in addition to those mandated by State law. Alternatively, State law may prohibit local legislation on this topic, thereby preempting local powers. APIS does not document policies established by local governments.
    
2. In addition to statutes and regulations, judicial decisions (case law) also may affect alcohol-related policies. APIS does not review case law except to determine whether judicial decisions have invalidated statutes or regulations that would otherwise affect the data presented in the comparison tables.
    
3. APIS reviews published administrative regulations. However, administrative decisions or directives that are not included in a State's published regulatory codes may have an impact on implementation. This possibility has not been addressed by the APIS research.
    
4. Statutes and regulations cited in tables on this policy topic may have been amended or repealed after the specific date or time period specified by the site user's search criteria.
    
5. A comprehensive understanding of the data presented in the comparison tables for this policy topic requires examination of the applicable Row Notes and Jurisdiction Notes, which can be accessed from the body of the table via links in the Jurisdiction column.

 (Policies in effect on: 1/1/2012)

BAC limits on Federal properties vary according to the type of lands involved, the Federal agency responsible for their regulation, and the geographic and jurisdictional relationships of any specific Federal land to contiguous privately owned land or land under the jurisdiction of other governmental entities.

For Federal lands under the administration of the National Park Service, a 0.08 per se BAC limit has been operative since September 5, 2003.  The applicable regulation applies to drivers who operate a vehicle on roadways or in parking areas within all park areas open to public traffic and that are under the legislative jurisdiction of the United States [36 C.F.R. § 4.23]. It also provides that "if State law that applies to operating a motor vehicle while under the influence of alcohol establishes more restrictive limits of alcohol concentration in the operator's blood or breath, those limits supersede the limits specified in this paragraph."

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1. Chang, K., Wu, C.C., and Ying, Y.H. The effectiveness of alcohol control policies on alcohol-related traffic fatalities in the United States. Accident Analysis & Prevention 45:406-415, 2012.
    
2. Fell, J.C., Fisher, D.A., Voas, R.B., Tippetts. A.S., and Blackman, K. Changes in alcohol-involved fatal crashes associated with tougher state alcohol legislation. Alcoholism: Clinical and Experimental Research 33(7):1208-1219, 2009.
    
3. Flowers, N.T., Naimi, T.S., Brewer, R.D., Elder, R.W., Shults, R.A., and Jiles, R. Patterns of alcohol consumption and alcohol-impaired driving in the United States. Alcoholism: Clinical and Experimental Research 32(4):639-644, 2008.
    
4. Kaplan, S., and Prato, C.G. Impact of BAC limit reduction on different population segments: A Poisson fixed-effect analysis. Accident Analysis and Prevention 39(6):1146-54, 2007.
    
5. National Institute on Alcohol Abuse and Alcoholism. Alcohol and Transportation Safety. Alcohol Alert No. 52. Rockville, MD: NIAAA.
    
6. Ramstedt M. Alcohol and fatal accidents in the United States–A time series analysis for 1950–2002. Accident Analysis & Prevention 40(4):1273-1281, 2008.
    
7. U.S. Department of Transportation, National Highway Traffic Safety Administration (NHTSA). Setting Limits, Saving Lives: The Case for 0.08 BAC Laws. Department of Transportation Highway Safety 809: 241, 2001.
    
8. Voas, R.B., and Fell, J.C. Preventing impaired driving opportunities and problems. Alcohol Research and Health 34(2):225-235, 2011.
    
9. Voas, R.B., Kelley-Baker, T., Romano, E., and Vishnuvajjala, R. Implied-consent laws: A review of the literature and examination of current problems and related statutes. Journal of Safety Research 40(2):77-83, 2009.
    
10. Wagenaar, A.C., and Maldonado-Molina, M.M. Effects of drivers' license suspension policies on alcohol-related crash involvement: Long-term follow-up in 46 states. Alcoholism: Clinical and Experimental Research 31(8):1399-1406, 2007.
     
11. Wagenaar, A.C., Maldonado-Molina, M.M., Ma, L., Tobler, A.L. and Komro, K.A. Effects of legal BAC limits on fatal crash involvement: Analyses of 28 states from 1976 through 2002. Journal of Safety Research 38(5):493-499, 2007.
     
12. Williams, A.F. Alcohol-impaired driving and its consequences in the United States: The past 25 years. Journal of Safety Research 37(2):123-38, 2006.