(a) Except as provided by Subsection (b), this subchapter applies only to a complaint against:
(1) a law enforcement officer of the State of Texas, including an officer of the Department of Public Safety or of the Texas Alcoholic Beverage Commission;
(2) a fire fighter who is employed by this state or a political subdivision of this state;
(3) a peace officer under Article 2A.001, Code of Criminal Procedure, or other law who is appointed or employed by a political subdivision of this state; or
(4) a detention officer or county jailer who is appointed or employed by a political subdivision of this state.
(b) This subchapter does not apply to a peace officer or fire fighter appointed or employed by a political subdivision that is covered by a meet and confer or collective bargaining agreement under Chapter 143 or 174, Local Government Code, if that agreement includes provisions relating to the investigation of, and disciplinary action resulting from, a complaint against a peace officer or fire fighter, as applicable.