What does it mean to drive under the influence (DUI)?

Driving under the influence (DUI) specifically refers to the act of operating a motor vehicle while impaired by alcohol, drugs, or a combination of both. This impairment is typically measured by Blood Alcohol Concentration (BAC), where exceeding the legal limit indicates a significant decrease in the driver's ability to operate the vehicle safely. The impact of drugs, whether illegal substances or prescribed medications, can similarly impair cognitive functions, motor skills, and judgment, leading to unsafe driving conditions.

The emphasis on BAC and drug presence highlights the legal standards used to evaluate whether a driver is unfit to drive. This is crucial as DUI laws are designed to enhance road safety by preventing impaired individuals from endangering themselves and others. Hence, this answer accurately captures the definition of DUI in the context of traffic law and enforcement.