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 South Dakota, it is indeed a criminal offense for a commercial driver to operate a commercial vehicle with a blood alcohol concentration (BAC) of .04 or higher, which is stricter than the .08 BAC limit for non-commercial drivers. Under South Dakota Codified Laws (SDCL), specifically SDCL 32-12A-17.1, a first-time DUI offense for a CDL holder can result in a one-year disqualification of their commercial driver's license. If the offense involves the transportation of hazardous materials, the disqualification period is extended to three years. A second DUI offense, under SDCL 32-12A-17.3, can lead to a lifetime disqualification, which may be reduced to 10 years upon meeting certain conditions. These penalties apply regardless of whether the CDL holder was driving a commercial or non-commercial vehicle at the time of the offense. It's important for CDL holders to be aware of these stringent regulations, as their livelihood depends on maintaining a clean driving record.