What constitutes "driving under the influence" (DUI)?

"Driving under the influence" (DUI) is defined primarily by the impairment of the driver's ability to operate a vehicle safely due to drugs or alcohol. A key legal benchmark for DUI is having a blood alcohol concentration (BAC) over 0.08%, which is the threshold commonly recognized to denote that a driver is too impaired to operate a vehicle safely.

This definition aligns with laws in many states, including Texas, which emphasize the combination of alcohol or drug impairment and the inability to drive safely. Therefore, whether a driver is above the established BAC limit or impaired by drugs, it constitutes driving under the influence as they may not be able to respond appropriately to driving conditions, maintain control of the vehicle, or make sound judgments, which are critical for safe driving.

The other choices do not fall under the legal definition of DUI. Driving while tired may lead to impaired driving but is not classified as DUI in the eyes of the law. Exceeding the speed limit pertains to traffic violations without relation to impairment. Holstering a firearm while driving is a separate issue regarding vehicle safety and firearm laws, but it does not pertain to DUI.