In Texas, a DUI is different than a DWI. The DUI (driving under the influence) statute forbids a minor (under 21) driving with any alcohol in his system. It is a class C misdemeanor, fine-only offense. If a minor is convicted of DUI but has no other alcohol-related convictions, the DUI can be expunged from his record when he turns 21.
The DWI (driving while intoxicated) statute, by contrast, forbids driving while intoxicated. “Intoxicated” means having a BAC over 0.08, or having lost the normal use of one’s mental or physical faculties. The penalty for a first DWI is up to 180 days in jail and a $2,000 fine. A DWI conviction can never be expunged.