I served as a vice-principal for 11 years in Merced County.  Students who used alcohol the first time in their 4-year attendance in the Merced Union High School District are suspended from school for 5 days.  Parent conferences are required as well.  Student athletes are also considered ineligible for a period of 9 weeks.  If found guilty in any alcohol or drug related case for a second time in their 4-year attendance, they are expelled from the Merced Union High School District.  I would suggest that if they were found guilty in an alcohol or drug related case near the end of their school year, their participation in graduation would be in jeopardy.  And, for information, the prom IS considered to be a school sponsored activity.