Tex. Local Government Code § 236.002

(a) Notwithstanding any other law, including Chapter 251, Agriculture Code, a county may not adopt or enforce regulations that:

(1) relate to:

(A) the transfer, possession, wearing, carrying, ownership, storage, transportation, licensing, or registration of firearms, air guns, archery equipment, knives, ammunition, or firearm or air gun supplies or accessories;

(B) commerce in firearms, air guns, archery equipment, knives, ammunition, or firearm or air gun supplies or accessories; or

(C) the discharge of a firearm, air gun, or archery equipment at a sport shooting range; or

(2) require an owner of a firearm or archery equipment to obtain liability insurance coverage for damages resulting from negligent or wilful acts involving the use of the firearm or archery equipment.

(b) An ordinance, rule, resolution, or policy adopted or enforced by a county, or an official action, including in any legislative, police power, or proprietary capacity, taken by an employee or agent of a county in violation of this section is void.

(c) Subsection (a) does not affect the authority of a county to:

(1) require a resident or public employee to be armed for personal or national defense, law enforcement, or other purpose under other law;

(2) regulate the discharge of firearms or air guns in accordance with Section 235.022;

(3) regulate the carrying of a firearm by a person licensed to carry a handgun under Subchapter H, Chapter 411, Government Code, in accordance with Section 411.209, Government Code;

(4) except as provided by Subsection (d), adopt or enforce a generally applicable land use regulation, fire code, or business regulation; or

(5) except as provided by Subsection (e), regulate or prohibit an employee's carrying or possession of a firearm, firearm accessory, or ammunition in the course of the employee's official duties.

(d) A county order or regulation designed or enforced to effectively restrict or prohibit the manufacture, sale, purchase, transfer, or display of firearms, firearm accessories, or ammunition that is otherwise lawful in this state is void.

(e) Subsection (c)(5) does not authorize a county to regulate an employee's carrying or possession of a firearm in violation of Subchapter G, Chapter 52, Labor Code.

(f) The attorney general may bring an action in the name of the state to obtain a temporary or permanent injunction against a county adopting a regulation, other than a regulation under Section 236.003, in violation of this section. The attorney general may recover reasonable expenses incurred in obtaining an injunction under this subsection, including court costs, reasonable attorney's fees, investigative costs, witness fees, and deposition costs.