Under FMCSA regulations, what is the blood alcohol concentration (BAC) limit for CDL drivers operating a commercial vehicle?

FMCSA ALCOHOL REGULATIONS (49 CFR 382): CDL drivers operating a Commercial Motor Vehicle (CMV) are subject to a BAC limit of 0.04% — exactly half the 0.08% limit for non-commercial drivers. This reflects the increased danger posed by impaired operation of a multi-ton vehicle. ADDITIONAL ALCOHOL RULES FOR CMV DRIVERS: (1) 4-HOUR PRE-DUTY: No alcohol consumption within 4 hours of going on duty or operating a CMV; (2) WHILE ON DUTY: No consumption at all; (3) POSSESSION: No possession of alcohol in the cab of a CMV (sealed containers being transported are an exception); (4) REFUSAL TO TEST: Treated as a positive test — immediate disqualification; (5) WHILE OFF-DUTY: Alcohol is permitted during off-duty periods, but the 4-hour pre-duty rule means CDL drivers must plan carefully. CONSEQUENCES OF VIOLATION: First offense at 0.04+ BAC while in CMV: 1-year CDL disqualification; if transporting hazmat: 3 years; second offense: lifetime CDL disqualification (disqualification can be reduced to 10 years if certain conditions are met). STATE REGULATION: Some states may have even stricter requirements — always check your operating state's specific commercial vehicle alcohol laws. The 0.08% personal vehicle limit still applies to a CDL holder driving a personal vehicle, but the commercial vehicle limit is 0.04%.