Chapter 4: DUI / DWI Laws

Driving is a privilege that requires a driver’s full attention and unimpaired judgment. Driving under the influence of alcohol or drugs is a leading cause of traffic fatalities and serious injuries in Maryland. Understanding these laws is not just about passing an exam; it is about recognizing a life-or-death responsibility to oneself, passengers, and every other person on the road.

Maryland has extremely strict laws against impaired driving, with severe penalties that affect a person’s freedom, finances, and driving privileges. The state uses a combination of criminal court proceedings and administrative MVA actions to penalize offenders. These laws apply not only to alcohol but to any drug—including illegal, prescription, or over-the-counter substances—that impairs a driver’s ability to operate a vehicle safely.

DUI & Implied Consent

Driving Under the Influence (DUI) and Driving While Impaired (DWI) are the two primary alcohol/drug-related driving offenses in Maryland. DUI is the more serious offense, while DWI is a lesser but still significant charge.

A person’s Blood Alcohol Concentration (BAC) is the primary measure of intoxication. It is the percentage of alcohol in the bloodstream. While a specific BAC level creates a legal presumption of impairment, a driver can be convicted at a lower BAC if evidence shows their coordination and judgment were affected.

BAC Limits

• 21 or Older: A BAC of .08% or higher is considered Driving Under the Influence (DUI). A BAC between .07% and .079% is considered Driving While Impaired (DWI).
• Under 21: Maryland has a “Zero Tolerance” policy. Any driver under 21 with a BAC of .02% or higher will have their license suspended or revoked. This is an administrative action, and they can also face criminal DWI/DUI charges.
• Commercial Vehicle Drivers: The BAC limit is .04% when operating a commercial vehicle.