Driving under the influence means that due to consumption of alcohol a person’s ability to drive was impaired to the point that they no longer could legally drive. The reason why the police give a breathalyzer test is to determine whether the results (.08 of BAC or higher) would create a presumption of impairment. So for example, someone who blows a .08 is presumed to be impaired. It should be noted that this is only a presumption and not a conclusion of law and as such may be refuted.
