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 Vermont, as in many states, the regulations for commercial vehicle drivers regarding DUI/DWI are stricter than for non-commercial drivers. Under Vermont law, a commercial driver is prohibited from operating a commercial vehicle with a blood alcohol concentration (BAC) of .04 or higher, which is indeed half the BAC limit for non-commercial drivers. For holders of a Commercial Driver's License (CDL), the consequences of a DUI/DWI conviction can be severe, impacting their livelihood. A first-time DUI/DWI offense can result in a one-year suspension of the CDL. If a CDL holder commits a second DUI/DWI offense, they face the possibility of being permanently disqualified from holding a CDL. These regulations are typically found in the state's motor vehicle or transportation codes.