It is unlawful for any social host of an event, gathering or party on the social host’s premises to knowingly permit or allow underage persons to consume controlled substances and/or alcoholic beverages, or knowingly permit or allow underage persons to possess controlled substances and/or alcoholic beverages on the premises. A social host that is present on the premises of the event, gathering, or party where consumption of controlled substances and/or alcoholic beverages is actually occurring is presumed to know the prohibited acts are occurring. This presumption is rebuttable. A social host has an affirmative defense if the social host took reasonable steps to prevent the possession or consumption of controlled substances and/or alcohol, or notified law enforcement and allowed law enforcement to enter the premises under the dominion and control of the social host for which the social host has authority to give consent to enter for the purpose of stopping the illegal activities.