Final answer:
Drivers under the age of 21 with a BAC of .02 or more are considered to be driving under the influence, in alignment with Zero Tolerance laws and the National Minimum Drinking Age Act of 1984.
Step-by-step explanation:
If you are a driver under the age of 21 and your blood alcohol concentration (BAC) is .02 or more, you are considered to be driving under the influence of alcohol. This falls under the Zero Tolerance laws aimed at preventing underage drinking and driving. Due to the National Minimum Drinking Age Act of 1984, states must enforce a minimum drinking age of twenty-one or face a reduction in federal highway funds, and Zero Tolerance laws are an extension of this policy. Being over the .02 BAC limit can lead to legal consequences, and this is a significantly lower threshold than the .08% BAC level used to define legal intoxication for drivers aged 21 and over.