In the State of Illinois, which of the following blood alcohol concentrations is considered legally under the influence?

In the State of Illinois, a blood alcohol concentration (BAC) of 0.08% is the legal threshold for being considered under the influence while operating a motor vehicle. This means that if an individual has a BAC at or above 0.08%, they can be charged with driving under the influence (DUI). This standard is based on extensive research indicating that impairment significantly increases at or above this level, affecting a person's judgment, coordination, and overall ability to drive safely.

The other levels listed—0.05%, 0.10%, and 0.12%—are not legally defined as the threshold for intoxication in Illinois. While a BAC of 0.05% may be significantly impaired for some individuals, it is not the legal limit. On the other hand, BAC levels of 0.10% and 0.12% are above the legal limit, meaning individuals at these levels would definitely be considered under the influence, but they don’t represent the defining point of legal impairment in Illinois law.