Nothing in criminal court is supoosed to be "automatic." You need to hire a lawyer to look into the conditions of your boyfriend's probation. Sometimes a person on probation is ordered to not drink to excess. If that is the case one drink would not be a violation. Even if it is a violation however, judges a supposed to consider the seriousness of the violation before sending someone to prison. If your boyfriend was seen having one glass of wine at dinner and someone else was driving for example a lawyer may be able to convince the judge to sanction him with a punishment less than prison. Community service hours, a fine, home confinement, etc. You and your boyfriend should hire an attorney in the Phoenix area who practices criminal defense. Good Luck.
In Arizona, when DUI defendants are sentenced to probation, they are almost universally prohibited from drinking during their term of probation. If it is supervised probation, probation officers typically (and randomly) test probationers for alcohol use (using urine tests). If the probationer has a positive alcohol test, or is arrested for another alcohol related offense (i.e., DUI, public consumption of alcohol, open container violation(s)), such conduct could be construed by the probation officer as a probation violation.
If your boyfriend was found to have consumed alcohol while on probation, the probation officer could file a probation violation allegation in Court, and your boyfriend could find himself back before the Court on a probation violation. Depending on the sentence he was originally sentenced on, if found guilty on the probation violation, he could be required to finish out his term in prison.
So to answer your question, it is not necessarily "automatic," but he could face a probation violation hearing if his probation officer alleges that he used alcohol while on probation, and if found guilty of the probation violation, could find himself back in prison.
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