Md. Code, State Personnel and Pensions § 28–201

(a) This subtitle applies only to an employee of a participating governmental unit who is:

(1) a law enforcement officer who is certified by the Maryland Police Training and Standards Commission as a law enforcement officer; or

(2) a firefighter who is:

(i) a paid firefighter, as determined by the eligible governmental unit; or

(ii) a paid paramedic, as determined by the eligible governmental unit.

(b) This subtitle does not apply to an employee of a participating governmental unit who is a volunteer firefighter or volunteer paramedic.