Which BAC level is commonly used as the legal threshold for driving under the influence for adults over 21?

Which BAC level is commonly used as the legal threshold for driving under the influence for adults over 21?

• A. .10 or greater
• B. .06 or greater
• C. .08 or greater
• D. .12 or greater

Answer: (B)

The level most commonly used as the legal threshold for DUI for adults over 21 is a blood alcohol concentration of 0.08% or higher. This per se limit means that once that BAC is reached or exceeded, driving can be deemed illegal based on BAC alone, regardless of how someone appears or feels. Research and practice show noticeable impairment in coordination, reaction time, and judgment around this level, which is why many states adopt 0.08% as the standard. The other values aren’t the standard baseline for adults over 21: 0.06 is below the typical limit and wouldn’t automatically establish DUI in most places, while 0.10 and 0.12 are higher thresholds that may apply if a driver happens to reach those levels, but they aren’t the common baseline. (Exceptions exist for special cases like commercial drivers or under-21 laws, but for adults over 21, 0.08% is the standard.)

The level most commonly used as the legal threshold for DUI for adults over 21 is a blood alcohol concentration of 0.08% or higher. This per se limit means that once that BAC is reached or exceeded, driving can be deemed illegal based on BAC alone, regardless of how someone appears or feels. Research and practice show noticeable impairment in coordination, reaction time, and judgment around this level, which is why many states adopt 0.08% as the standard. The other values aren’t the standard baseline for adults over 21: 0.06 is below the typical limit and wouldn’t automatically establish DUI in most places, while 0.10 and 0.12 are higher thresholds that may apply if a driver happens to reach those levels, but they aren’t the common baseline. (Exceptions exist for special cases like commercial drivers or under-21 laws, but for adults over 21, 0.08% is the standard.)