(a) It shall be unlawful to loiter with intent to interfere with or disrupt the school program or with intent to interfere with or endanger school children in a school building or on school grounds or within 100 feet of school grounds when persons under the age of 18 are present in the building or on the grounds, not having any reason or relationship involving custody of or responsibility for a pupil or any other specific, legitimate reason for being there and having been asked to leave by a school administrator or his or her representative or by a peace officer. For purposes of this section, the term "loiter" means to be dilatory; to stand idly around; to linger, delay or wander about; or to remain, abide, or tarry in a public place.

(b) It shall be an affirmative defense that the defendant's acts were lawful and he or she was exercising his or her rights of lawful assembly as a part of peaceful and orderly petition for the redress of grievances, either in the course of labor disputes or otherwise. (Code 1979, § 27-51)