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Blood Alcohol Concentration (BAC) Limits

Adult Operators of Noncommercial Motor Vehicles

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.

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

  1. BAC Limit

    • Blood alcohol concentration (BAC) is a measure of the amount of alcohol in a person's bloodstream. Although BAC levels are commonly expressed in percentage terms, 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).
  2. Per se
    • Per se statute is present (check):

      • Identifies jurisdictions with per se BAC statutes. These statutes specify the BAC level at which a person is operating a motor vehicle illegally. If the operator is shown to have a BAC level at or above the per se limit, a violation has occurred without regard to other evidence of intoxication or sobriety. The BAC limit by itself establishes a violation. As of June 30, 2003, all jurisdictions have enacted per se BAC laws for adults operating noncommercial motor vehicles.
    • Per se statute not present (column is blank):
      • Identifies jurisdictions without per se BAC statutes (historical data only). The BAC limit provides evidence of being under the influence of alcohol while operating a motor vehicle, but it does not, by itself, constitute a violation. Under these statutes, defendants can provide evidence that, in spite of the BAC level, they were not under the influence and therefore not in violation. The weight given to the BAC level evidence may vary across jurisdictions. 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.