Driving under the influence (DUI) can have many repercussions, including jail and fines. But for CDL holders, a DUI (whether it occurred driving a commercial truck or personal vehicle) can mean the loss of their commercial license, and so their livelihood for at least a year.
Among the states, there are many definitions of "driving under the influence." But all states have stricter standards for drivers operating commercial motor vehicles (CMVs) than those that apply to drivers operating personal vehicles.
All states prohibit driving under the influence. And, while each state has different thresholds for determining when a driver is legally under the influence, a driver can generally be convicted of a DUI for:
These standards, which apply to all drivers, also apply to CDL holders who are operating personal, non-commercial vehicles.
The legal BAC limit is lower for commercial drivers who are driving a CMV. In all states, it's illegal to operate a CMV with a BAC of .04% or more. The .04% BAC limit is required by federal law. However, some states have even stricter laws that set the BAC limit lower for certain CDL holders or contain prohibitions related to controlled substances.
All commercial drivers are considered to have impliedly consented to a chemical test to determine the presence and amount of drugs or alcohol in their system. In other words, CDL holders must comply with an officer's lawful request to submit to testing. Typically, the testing would consist of a blood, breath, or urine test. Each state has slightly different rules for when a driver is required to test. But all states must comply with the federal requirement that an unlawful chemical test refusal (classified as a "major violation") mandates CDL disqualification for at least one year.
The federal rules require any CDL holder who's convicted of a test refusal, a DUI, or driving a CMV with a BAC of .04% to be disqualified for at least one year. A DUI committed in a CMV carries at least three years of disqualification if the offense occurred in a hazmat CMV. A second or subsequent DUI conviction will result in lifetime CDL disqualification.
Aside from the mandatory disqualification for a DUI conviction, alcohol and drug-related offenses have additional impacts on a CDL. A CMV driver who is caught with any amount of alcohol or drugs in his or her system will be immediately prohibited from driving a CMV for a duration of at least 24 hours.
Also, some states have adopted something called the "Drug and Alcohol Clearinghouse," which automatically disqualifies a CDL holder for any positive drug or alcohol test. The driver will be disqualified until completing a substance abuse evaluation and the recommended treatment.