California Code, Penal Code - PEN § 627.9

(a) Exempt the district or any school or class of schools in the district from the operation of this chapter.

(b) Make exceptions to Section 627.2 for particular classes of outsiders.

(c) Authorize principals to exempt individual outsiders from the operation of Section 627.2; but any such exemption shall be in a writing which is signed and dated by the principal and which specifies the person or persons exempted and the date on which the exemption will expire.

(d) Exempt, or authorize principals to exempt, designated portions of school grounds from the operation of this chapter during some or all school hours.