In most states, driving with which BAC level is illegal?

• A. 0.00%
• B. 0.04%
• C. 0.08%
• D. 0.12%

Answer: (C)

A practical rule is that driving with a BAC around 0.08% is illegal because that level reliably impairs key driving abilities. At this concentration, most people experience noticeable declines in concentration, coordination, balance, and judgment, which makes it much harder to react to hazards, stay in a lane, and track moving objects. That combination dramatically raises crash risk, so many states set 0.08% as the legal limit for non-commercial drivers. There are stricter limits for other groups—commercial drivers are often limited to 0.04%, and many jurisdictions have zero tolerance for those under 21. The other BAC levels aren’t the standard baseline for illegal driving: 0.04% is typically not the general limit for all drivers, 0.12% is simply a higher level, and 0.00% is not illegal by itself.