What is the primary legal standard for determining intoxication?

The primary legal standard for determining intoxication is centered around the ability to operate a motor vehicle safely. This principle is rooted in the idea that driving is a privilege that comes with responsibilities, including the obligation to ensure public safety. Law enforcement officers often evaluate an individual's physical and cognitive capabilities when determining if they are fit to drive, which directly relates to their ability to operate a vehicle safely.

While blood alcohol content (BAC) levels are used as a quantifiable measure of impairment—typically with legal thresholds defined by law—the ability to drive safely encompasses a broader evaluation of behavior, coordination, and decision-making, which are ultimately what affects road safety. The presence of illegal substances and the time since last consumption of alcohol may factor into the larger context of intoxication, but they do not serve as the definitive legal benchmark for assessing whether someone is too impaired to drive safely.

Focusing on safe operation reflects lawmakers' intent to prioritize the safety of the public over strict numerical measurements of intoxication.