Under Wisconsin law, a driver is considered to be operating while intoxicated if:

• The driver is under the influence of an intoxicant, controlled substance or any other drug so that their ability to safely operate a vehicle is impaired even if the vehicle is not in motion at the time of the traffic stop; or
• The driver has blood/breath alcohol concentration (BAC) in excess of what the law allows. The Prohibited Alcohol Concentration (PAC) for first offenders is 0.08* or greater (0.04* for those operating a commercial vehicle at the time of the stop);
• The driver has a detectable amount of a restricted controlled substance in their blood
• Drivers with three or more prior OWI convictions cannot operate a motor vehicle if their BAC is greater than 0.02.

*Note: Alcohol concentrations are measured in grams of ethanol per 100 milliliters of blood.

Drivers under 21 years of age are required by law, under Graduated Driver License (GDL) restrictions, to maintain absolute sobriety and, for them, driving with any amount of alcohol in their system is illegal.

Penalties for operating a motor vehicle while intoxicated range from a forfeiture and license revocation for a first offense, to up to six years imprisonment and a lifetime license revocation for subsequent offenses. Additionally, more severe penalties apply if injury or death results.

• Offenses and penalties for OWI range in severity depending on the type of offense and number of repeat offenses:
• OWI and related alcohol and drug offense penalties (as of October 1, 2020)
• Underage alcohol offenses and related penalties (as of June 1, 2017)
• Commercial driver license alcohol and other drug offenses and related penalties (as of May 7, 2018)