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 Indiana, 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. Upon a first DUI/DWI offense, a CDL holder in Indiana can face a one-year suspension of their CDL. If the offense involves transporting hazardous materials, the suspension period can extend to three years. A second DUI/DWI conviction can result in a lifetime disqualification from holding a CDL, which may be reduced to 10 years under certain conditions. These regulations are designed to ensure the safety of the roads and to hold commercial drivers to a higher standard given the potential for greater harm due to the size and weight of commercial vehicles. The specific laws governing these offenses and penalties in Indiana can be found in the Indiana Code, particularly in the sections related to motor vehicles and traffic regulations.