Drunk Driving: the act of operating a motor vehicle after having consumed alcohol or other drugs, to the degree that mental and motor skills are impaired. All 50 states now have two statutory offenses. The first is the traditional offense, variously called driving under the influence of alcohol (DUI), driving while intoxicated/impaired (DWI) or operating while intoxicated/impaired (OWI). The second and more recent is the so-called illegal per se offense of driving with a blood-alcohol concentration (BAC) of 0.08% (previously 0.10%) or higher. The first offense requires proof of intoxication, although evidence of BAC is admissible as presumptive evidence of that intoxication; the second requires only proof of BAC at the time of being in physical control of a motor vehicle. An accused may be convicted of both offenses, but may only be punished for one. It is also a criminal offense in all states to drive a vehicle while under the influence of drugs DUID, or under the combined influence of alcohol and drugs; the drugs themselves need not be illegal, but can be prescription or even over-the-counter. This offense requires evidence of impairment as a result of the drugs or drugs and alcohol. All states also now have zero tolerance laws: the license of anyone under 21 driving with a BAC of .01% or higher (.02% in some states) will be suspended. The blood-alcohol limit for commercial drivers 0.04%.