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 California, the regulation for commercial drivers regarding DUI/DWI is indeed stricter compared to non-commercial drivers. Under California Vehicle Code Section 23152(d), it is illegal for a person who has a blood alcohol concentration (BAC) of 0.04% or more to operate a commercial vehicle. This is half the legal limit for non-commercial drivers, which is 0.08%. For holders of a commercial driver's license (CDL), the consequences of a DUI conviction can be severe, impacting their livelihood. A first-time DUI offense can lead to a one-year suspension of the CDL. If a CDL holder commits a second DUI, they face the possibility of a lifetime disqualification from holding a CDL. These penalties apply regardless of whether the DUI occurred while driving a commercial or non-commercial vehicle. It's important for CDL holders to be aware of these stringent regulations and the potential impact on their career.