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 Texas, the regulation regarding the operation of a commercial vehicle by drivers with a Commercial Driver's License (CDL) under the influence of alcohol is strict. The legal limit for blood alcohol concentration (BAC) for CDL holders operating a commercial vehicle is .04, which is indeed half the limit of .08 that applies to non-commercial drivers. If a CDL holder is convicted of Driving Under the Influence (DUI) or Driving While Intoxicated (DWI) in a commercial vehicle, or even in a non-commercial vehicle, the consequences are severe. For the first offense, the CDL holder faces a one-year suspension of their CDL. If a CDL holder commits a second DUI/DWI offense, they may face a lifetime disqualification from holding a CDL. These regulations are designed to ensure the safety of the roads and to hold commercial drivers to a higher standard due to the potential consequences of operating larger vehicles while impaired. The relevant laws can be found in the Texas Transportation Code, which outlines the penalties and processes for DUI/DWI offenses for CDL holders.