Violations of good conduct rules may be punished by barring the student from participation in extracurricular activities for a period of time set by the board policy (see Q & A regarding the length of this suspension, link below).
Extracurricular activities are those voluntary activities outside the regular program of courses, such as interscholastic athletics, speech, student council, drama, etc. The Iowa District Court for Sac County has ruled that prom is an extracurricular activity subject to a school's good conduct policy, but commencement is not.
Wall Lake View Auburn v. Iowa Board of Education. #LACV017977 (Sac County District Court. 1999). Q & A regarding the length of this suspension: https://www.edinfo.state.ia.us/web/appeals_float.asp?book=16&decision=269