If the individual is engaged in the enforcement or prosecution of this title or other law relating to controlled dangerous substances, criminal liability may not be imposed under this title on: an authorized officer of the United States, this State, or a political subdivision of this State; or an authorized police department civilian employee of the United States, this State, or a political subdivision of this State. A public official or employee who is covered under subsection (a) of this section may temporarily possess controlled dangerous substances, drug paraphernalia, or controlled paraphernalia incidental to the discharge of official or employee duties.