Laws that declare it illegal to drive a vehicle
above a certain alcohol level, as measured by a blood or breath
test. In most states, the per se limit is .08% or greater. Violating
the per se law has nothing to do with one's ability to drive a car
safely; it is based solely on body chemistry. The only question is
whether the driver was above the legal limit at the time of driving.
NOTE: since breath or blood testing always takes place after the
time of driving, it does not directly answer the question of BAL at
the time of driving. The alcohol level at the time of testing may be
higher, lower, or the same, when compared to the time of driving.