569.155.  Trespass of a school bus, penalty — schools to establish student behavior policy, when. — 1.  A person commits the offense of trespass of a school bus if he or she knowingly and unlawfully enters any part of or unlawfully operates any school bus.

  2.  For the purposes of this section, the terms "unlawfully enters" and "unlawfully operates" refer to any entry or operation of a school bus which is not:

  (1)  Approved of and established in a school district's written policy on access to school buses; or

  (2)  Authorized by specific written approval of the school board.

  3.  In order to preserve the public order, any district which adopts the policies described in subsection 2 of this section shall establish and enforce a student behavior policy for students on school buses.

  4.  The offense of trespass of a school bus is a class A misdemeanor.