California Code, Penal Code - PEN § 627

(a) The Legislature finds the following:

(b) The Legislature declares that the purpose of this chapter is to safeguard the teachers, other employees, students, and property of public schools.  The Legislature recognizes the right to visit school grounds for legitimate nonviolent purposes and does not intend by this enactment to interfere with the exercise of that right.

(c) The Legislature finds and declares that a disproportionate share of crimes committed on school campuses are committed by persons who are neither students, school officials, or staff, and who have no lawful business on the school grounds.

It is the intent of the Legislature in enacting this chapter to promote the safety and security of the public schools by restricting and conditioning the access of unauthorized persons to school campuses and to thereby implement the provisions of Section 28 of Article 1 of the California Constitution which guarantee all students and staff the inalienable constitutional right to attend safe, secure, and peaceful public schools.  It is also the intent of the Legislature that the provisions of this chapter shall not be construed to infringe upon the legitimate exercise of constitutionally protected rights of freedom of speech and expression which may be expressed through rallies, demonstrations, and other forms of expression which may be appropriately engaged in by students and nonstudents in a campus setting.