What is the legal limit for blood alcohol concentration (BAC) in almost all states?

• A. 0.00%
• B. 0.05%
• C. 0.10%
• D. 0.08%

Answer: (D)

In driving law, the key point is the level at which a person is considered legally impaired to operate a vehicle. For adults 21 and over, the standard limit in almost every state is 0.08% BAC. Crossing that threshold means you’re treated as legally impaired, and you can be charged with driving under the influence. It’s important to note that impairment can begin below this level, but the law uses 0.08% as the per se limit that defines illegal driving.

Other numbers aren’t the general limit for the typical adult driver. Zero tolerance or 0.00% is used in specific contexts (like some provisions for minors or certain professional drivers), not the standard for all adults. A lower figure like 0.05% is used in some countries or regions, but not the common standard in almost all U.S. states. A higher figure like 0.10% used to be more common in the past, but the current widespread standard is 0.08%.