There are many types of activities on campus that are prohibited by law.
School Site Interruptions
Governing boards are required to post at every entrance to each school and grounds a notice setting forth "school hours" as defined by the board. Ed. Code 32211.
No outsider shall enter or remain on school ground during school hours without having registered with the principal. PEN. Code 627.2.
Any person who comes into a school building or upon school grounds, street, sidewalk or public way adjacent thereto, without lawful business, and whose presence or acts interfere with the peaceful conduct of school activities or disrupt the school or its pupils may be asked to leave the premises. Failure to comply with such a request when made by the school's chief administrative official or designee, or any attempt to reenter the prohibited premises within 7 days after being asked to leave, constitutes a misdemeanor. Upon first conviction, such person may be punished by a fine not to exceed $500, by imprisonment not to exceed six months, or by both a fine and imprisonment. PEN. Code 626.8.
Any person other than a student, parent or guardian, or employee of the school district shall promptly depart from the school premises during school hours when requested to do so by the school principal or designee. Such person shall not return for at least thirty (30) days. The request to leave shall be made exclusively on the basis that it appears reasonable to conclude that the continued presence of the person would be disruptive of, or interfere with, classes or other school activities. Failure to comply promptly with the request to remain off the school premises for 30 days constitutes a misdemeanor. Any person requested to leave the premises may appeal his expulsion to the district superintendent and ultimately to the governing board. PEN. Code 626.7; Ed. Code 2211.
Every person who loiters about any school, or who reenters a school within 72 hours after being asked to leave, is a vagrant and subject to a fine. PEN. Code 653(b.)
Every minor over 16 or adult who is not a pupil of the school who enters any school ground and willfully interferes with discipline, good order, lawful conduct, or administration of any class or school activity with the intent to disrupt, obstruct, or to inflict damage to property or bodily injury to any person, is guilty of a misdemeanor which is punishable by a fine of not less than $500 or more than $1,000, or by imprisonment in county jail for up to one year, or both. Ed. Code 44810.
Any person who willfully disturbs any public school or any public school meeting is guilty of a misdemeanor and shall be subject to a fine of not more than $500. Ed. Code 32210.
Any specified drug offender who enters school grounds or an adjacent street, sidewalk or public way within seven days after being asked to leave by a school official or public safety officer, is guilty of a misdemeanor punishable by a fine of $1,000 or up to six months in jail or both, unless the drug offender is a student or a parent or guardian of a student or has prior written permission to enter. PEN. Code 626.85.
It is the intent of the Legislature that each school district board formally address the problem of classroom interruptions and adopt a policy to control those interruptions. Ed. Code 32212.
Any parent, guardian or other person whose conduct in a place where a school employee is required to be in the course of his or her duties, materially disrupts classwork or extracurricular activities or involves substantial disorder, is guilty of a misdemeanor. This section does not apply to any otherwise lawful employee concerted activity. Ed. Code 44811.
Unauthorized Entry on School Bus
Any person who enters a school bus without proper authorizations, with the intent to commit any crime and who refuses to disembark is guilty of a misdemeanor punishable by a fine of up to $1000, or up to six months in jail, or both. Ed. Code 39842.
Threats to Personal Safety
It is a public offense to cause or attempt to cause any school employee to do, or refrain from doing his duties, by directly communicating a threat to injure their person or property, where the person threatened reasonably believes that such a threat could be carried out. Such offense is punishable by a fine up to $10,000, or up to one year in jail or both. PEN. Code 71.
Any person, except a registered student of the school, who (1) fights or challenges another to a fight on school grounds, or (2) maliciously and willfully disturbs another person in a school building or on school grounds by loud and unreasonable noise, or (3) uses offensive words likely to provoke immediate, violent reaction is guilty of a misdemeanor punishable by a series of penalties dependent upon whether the offense is a first offense or the offender has previous convictions. PEN. Code 415.5.
An assault or battery committed on school property against any person is punishable by a fine not to exceed two thousand dollars ($2,000), or by imprisonment in the county jail not to exceed one year, or by both. PEN. Code 241.2, 243.2. An assault is an unlawful attempt, coupled with a present ability, to commit a violent injury on the person of another. PEN. Code 240. A battery is any willful and unlawful use of force or violence upon the person of another. PEN. Code 242.
A peace officer may, without a warrant, arrest a person who commits an assault or battery on school property during hours when school activities are being conducted if:
1. The person has committed the assault or battery, although not in the peace officer's presence, or
2. The peace officer has reasonable cause to believe that the person to be arrested has committed the assault or battery, whether or not it has, in fact, been committed. PEN. Code 243.5(a).
Weapons and Ammunition
Any person who brings a firearm within 1,000 feet of the grounds of any public or private school, college, or university, may be imprisoned for up to five years under specified circumstances. Any person who recklessly discharges a firearm in such a "school zone" may be imprisoned for three, five, or seven years. PEN. Code 266.9. It is a public offense, punishable by up to one year in jail, to bring or possess any weapon on the premises of any public school. PEN. Code 626.10. Except as specified, any person who carries any ammunition onto school grounds may be imprisoned for six months. PEN Code 12316.
A minor shall not possess live ammunition or a pistol, revolver or other firearm capable of being concealed on the person except under specified circumstances including where the minor is accompanied by his or her parent or guardian. Violation is punishable by imprisonment for up to one year, by 50-500 hours of community service, and by the withholding, suspension or revocation of the minor's driver's license until age 18. The custodial parent or guardian may be ordered to participate in parenting education classes. PEN. Code 12101.
It is a misdemeanor to possess aerosol paint, felt-tip markers, or other marking instruments with the intent to commit graffiti or vandalism. PEN. Code 594.1.
Hate and Violence
Under the California Schools Hate and Violence Reduction Act of 1995 for pupils in grades K-12, if private funding is available, the State Board of Education is directed to adopt policies and procedures to prevent and respond to acts of hate violence and bias-related incidents, revise state curriculum frameworks and guidelines to include human relations education; establish guidelines for teacher and administrator in-service to promote appreciation of diversity, discourage discrimination and prevent acts of hate violence. Ed. Code 44806.