According to Georgia law, anyone driving with an elevated blood alcohol content or any amount of illegal drugs in their system is considered to be driving while under the influence and can be arrested. The legal limit of blood alcohol concentration varies for different groups. The legal limit for anyone under 21 years old is a BAC of .02% or higher. For adults over 21, a BAC of .08% or higher is considered drunk driving. For a commercial driver, such as a truck driver, the limit is .04% BAC or higher.