Vision, coordination, reasoning, balance and the ability to process information are all negatively impacted by your blood alcohol content. You need all of those things to safely operate a vehicle.
While you are not legally impaired until your BAC reaches .08, you will likely feel the effects of alcohol long before it reaches that point.
Beginning of impairment
Blood alcohol content levels of .02 can cause lightheadedness and impaired judgment. Your vision starts to suffer as well as your ability to do two things at once, making driving a challenge. By the time your BAC reaches .05, you begin to feel lowered inhibitions and heightened emotions. People refer to this stage as ‘buzzed’ because of the euphoric feeling. You also begin to experience reduced coordination and may have difficulty steering and slower reaction time behind the wheel.
When your BAC reaches .08, you are legally impaired. Along with the worsening of all the other symptoms listed above, your speech begins to slow or slur, and fatigue sets in. You experience impaired concentration, perception and short-term memory. You also lose some ability to process information. All of these impairments make you very dangerous on the road.
As your BAC goes higher and higher, your ability to drive becomes more and more impaired. A BAC of .10 causes an inability to stay in your lane or safely apply brakes. By the time you reach .15, your gross motor skills and perception are extremely impaired. You will have great trouble paying attention to what you are doing behind the wheel.
The more you drink, the less control you have over your thoughts, coordination, balance, processing skills and reactions. Even a slight impairment at the lower BAC levels is enough to negatively affect your ability to safely operate a vehicle.