(a) As used in this Section, “officer-involved shooting” means any instance when a law enforcement officer discharges his or her firearm, causing injury or death to a person or persons, during the performance of his or her official duties or in the line of duty.
     (b) Each law enforcement agency shall adopt a written policy regarding drug and alcohol testing following an officer-involved shooting. The written policy adopted by the law enforcement agency must include the following requirements:
         (1) each law enforcement officer who is involved in