Tex. Penal Code Section 9.43
Protection of Third Person’s Property

A person is justified in using force or deadly force against another to protect land or tangible, movable property of a third person if, under the circumstances as he reasonably believes them to be, the actor would be justified under Section 9.41 (Protection of One’s Own Property) or 9.42 (Deadly Force to Protect Property) in using force or deadly force to protect his own land or property and:

(1)

the actor reasonably believes the unlawful interference constitutes attempted or consummated theft of or criminal mischief to the tangible, movable property; or

(2)

the actor reasonably believes that:

(A)

the third person has requested his protection of the land or property;

(B)

he has a legal duty to protect the third person’s land or property; or

(C)

the third person whose land or property he uses force or deadly force to protect is the actor’s spouse, parent, or child, resides with the actor, or is under the actor’s care. Acts 1973, 63rd Leg., p. 883, ch. 399, Sec. 1, eff. Jan. 1, 1974. Amended by Acts 1993, 73rd Leg., ch. 900, Sec. 1.01, eff. Sept. 1, 1994.