Understanding .08

One day, MADD hopes to put an end to drunk driving through the development of in-vehicle technology that automatically determines whether or not a driver is at or above the legal limit of .08 blood alcohol concentration and signals the car not to operate if the driver is impaired.  If you would like to support this vital technology, you can email your representatives here.

In the meantime, how does an adult over the age of 21 make smart choices about drinking and driving? 

What is .08?

Alcohol decreases a person’s ability to drive a motor vehicle safely. The more you drink, the greater the effect. The amount of alcohol required to become impaired differs according to how fast you drink, your weight, your gender, and how much food you have in your stomach.  Because of these variables, the safest choice is always not to drink and drive.

Blood Alcohol Concentration (g/dL)¹

Typical Effects

Predictable Effects on Driving



• Some loss of judgment
• Relaxation
• Slight body warmth
• Altered mood

• Decline in visual functions (rapid tracking of a moving target)
• Decline in ability to perform two tasks at the same time (divided attention)


• Exaggerated behavior
• May have loss of small-muscle control (e.g., focusing your eyes)
• Impaired judgment
• Usually good feeling
• Lowered alertness
• Release of inhibition

• Reduced coordination
• Reduced ability to track moving objects
• Difficulty steering
• Reduced response to emergency driving situations


• Muscle coordination becomes poor (e.g., balance, speech, vision, reaction time, and hearing)
• Harder to detect danger
• Judgment, self-control, reasoning, and memory are impaired

• Concentration
• Short-term memory loss
• Speed control
• Reduced information processing capability (e.g., signal detection, visual search)
• Impaired perception


• Clear deterioration of reaction time and control
• Slurred speech, poor coordination, and slowed thinking

• Reduced ability to maintain lane position and brake appropriately


• Far less muscle control than normal
• Vomiting may occur (unless this level is reached slowly or a person has developed a tolerance for alcohol)
• Major loss of balance

• Substantial impairment in vehicle control, attention to driving task, and visual and auditory information processing

¹ Information in this table shows the BAC level at which the effect usually is first observed, and has been gathered from a variety of sources including the National Highway Traffic Safety Administration, the National Institute on Alcohol Abuse and Alcoholism, the American Medical Association, the National Commission Against Drunk Driving, and www.webMD.com.

Please let your representatives know you support cars that won't drive above .08 BAC.