In Texas, a person of any age can be convicted of driving while intoxicated (DWI) for operating a motor vehicle:
However, Texas also has special laws that apply only to underage drivers who get behind the wheel after drinking.
Because it's illegal for anyone who's underage to consume alcohol in Texas, the state has enacted alcohol "zero tolerance" rules for drivers under age 21. Underage drivers with "any detectable amount of alcohol" in their system can be convicted of driving under the influence of alcohol ("DUIA"), whether they are actually intoxicated or not. And minors who meet the DWI standard for intoxication as described above can be convicted of both DWI and DUIA.
The consequences of receiving a DUIA vary depending on the driver's age. For a motorist who's less than 17 years old, DUIA is a Class C misdemeanor. A first conviction carries a fine of up to $500, a minimum 60-day license suspension, and 20 to 40 hours of community service. Attendance in an "Alcohol Awareness Course"—for the minor and possibly the parent—is also required.
For a motorist age 17 to 20, DUIA is Class B misdemeanor. Depending on whether the underage driver has prior infractions, a conviction carries up to $2,000 in fines, jail time from 72 hours to 180 days, and a minimum 1-year license suspension. The suspension can be reduced to 90 days when coupled with community supervision and use of an ignition interlock device (IID).
Under Texas's "implied consent" law, underage motorists who are lawfully arrested for DUIA must submit to blood or breath BAC chemical testing. Underage drivers who refuse can be jailed until they either appear before a juvenile court judge or post bond. Additionally, the refusal will result in a 180-day driver's license suspension (or delay in obtaining driving privileges if unlicensed).
Regardless of the charge, it's always best to talk to an experienced DWI/DUIA attorney. A qualified lawyer can tell you how the law applies to your situation and help you decide on the best course of action.