After campus protests against the Vietnam War in the late 1960s, participation in the ROTC became voluntary in 1969.[23] The same year other regulations were changed: the requirement that students wear coat and tie to class was dropped,[24] students of age were allowed to drink in the dormitories,[25] and only underclassmen with failing grades were subject to a curfew.[26] After 1970 females could visit male dormitories until 10:00 p.m. on weekdays and 2:00 a.m. on weekends.[27] The common core curriculum added options after 1970.[28]