Illegal Per Se “Illegal per se” means that the operation of a vehicle by a person with a blood alcohol content (BAC) at or above the legally defined threshold constitutes an offense of impaired driving in and of itself. Nevada’s blood alcohol limit is .08 and .04 for commercial drivers. Note that these limits are only guides. Drivers can be arrested and convicted for DUI with a lower BAC reading or for driving under the influence of controlled or prohibited substances.