When a minor child under the age of 18 years must of necessity by virtue of employment, night school, school activity, or other lawful pursuit be in or upon any street, highway, park, or other public place within the corporate limits of the city of Maywood Park without the supervision of a parent or guardian at least 21 years of age between the above specified hours, the burden of proof thereof shall be upon the minor child or person claiming the exempt status of being engaged in a lawful pursuit. [Ord. 2009-5 § 3, 2009.]