In what situations are school officials justified in searching without a warrant or probable cause if they have reasonable suspicion to believe contraband exists?

The Supreme Court has held that students enjoy less constitutional protections while on school property. Lockers are school property and thus do not require a warrant to search. As for a students person, they must have probable cause. A students witness statement may not be enough to justify a search of a student. However, a camera placing you in the area when something was stolen could certainly justify a search for the stolen objects (contraband). As for drugs, if you appear intoxicated or are behaving in a suspect manner, this too may be probable cause to search you for any kind of narcotics.