TexasCHLforum.com

Quick and dirty explanation:

Sec. 9.21. PUBLIC DUTY. (a) Except as qualified by Subsections (b) and (c), conduct is justified if the actor reasonably believes the conduct is required or authorized by law, by the judgment or order of a competent court or other governmental tribunal, or in the execution of legal process. Think of the authority a LEO has to use force again a person to make an arrest.

(b) The other sections of this chapter control when force is used against a person to protect persons (Subchapter C), to protect property (Subchapter D), for law enforcement (Subchapter E), or by virtue of a special relationship (Subchapter F). Self-explanatory.

(c) The use of deadly force is not justified under this section unless the actor reasonably believes the deadly force is specifically required by statute or unless it occurs in the lawful conduct of war. If deadly force is so justified, there is no duty to retreat before using it. Deadly must be specifically authorized in order to use it under this section. Think of an executioner.

(d) The justification afforded by this section is available if the actor reasonably believes:

(1) the court or governmental tribunal has jurisdiction or the process is lawful, even though the court or governmental tribunal lacks jurisdiction or the process is unlawful; or If an order is overturned or determined to be unlawful, you are justified as long as you reasonably believed it was lawful.

(2) his conduct is required or authorized to assist a public servant in the performance of his official duty, even though the servant exceeds his lawful authority. If a LEO directs you to assist with an action or asks for help, and the action is unlawful (like an unlawful arrest), you are still justified.