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 Mississippi, it is indeed a criminal offense for a commercial vehicle operator to have a blood alcohol concentration (BAC) of .04 or more, which is in line with federal regulations set by the Federal Motor Carrier Safety Administration (FMCSA). For holders of a Commercial Driver's License (CDL), the consequences of a DUI/DWI are particularly severe. Under Mississippi law, a first-time DUI offense for a CDL holder can result in a one-year suspension of their CDL. If the CDL holder commits a second DUI/DWI offense, they face the possibility of a lifetime disqualification from holding a CDL. These regulations apply regardless of whether the CDL holder was driving a commercial or non-commercial vehicle at the time of the offense. The relevant laws are typically found in the state's transportation or vehicle code.