In many states it is a criminal offense (DUI/DWI) to operate a commercial vehicle with a blood alcohol concentration of .04 or more—which is half of the BAC usually required to commit the DUI/DWI offense while driving a non-commercial vehicle. Because most holders of commercial driver’s licenses (CDLs) depend on their license to earn a living, the consequences of a DUI/DWI conviction for a CDL holder—including a conviction while operating a non-commercial vehicle—are serious.

Laws vary from state to state but a CDL holder’s license may be suspended for one year for the first offense, and with a second DUI/DWI conviction the CDL holder may be permanently disqualified from holding a CDL.

These laws are generally located in a state’s statutes—often in the vehicle code, motor vehicle code, or transportation code.

In Wisconsin, it is indeed a criminal offense for a commercial vehicle operator to have a blood alcohol concentration (BAC) of .04 or higher, which is in line with federal regulations. This limit is specifically lower than the .08 BAC limit for non-commercial drivers. For holders of a Commercial Driver's License (CDL), the consequences of a DUI/DWI are severe due to their reliance on their license for employment. Under Wisconsin law, a first offense DUI/DWI can result in a one-year disqualification of the CDL. If a CDL holder commits a second DUI/DWI, they face a lifetime disqualification from holding a CDL, with the possibility of reinstatement after 10 years under certain conditions. These regulations are designed to promote safety on the roads and ensure that commercial vehicle operators adhere to stricter standards due to the potential for greater harm. The relevant laws can be found in the Wisconsin Statutes, specifically within the sections dealing with motor vehicles and transportation.