Right, it becomes a matter of impairment, not blood alcohol level. But you can certainly have one beer on an empty stomach, have a BAC of 0.04 and drive around

Right, it becomes a matter of impairment, not blood alcohol level. But you can certainly have one beer on an empty stomach, have a BAC of 0.04 and drive around. As long as you aren't visibly impaired, it's legal.