Tex. Penal Code § 9.44: USE OF DEVICE TO PROTECT PROPERTY.

The justification afforded by Sections 9.41 and 9.43 applies to the use of a device to protect land or tangible, movable property if:

(1) the device is not designed to cause, or known by the actor to create a substantial risk of causing, death or serious bodily injury; and

(2) use of the device is reasonable under all the circumstances as the actor reasonably believes them to be when he installs the device.

Acts 1973, 63rd Leg., p. 883, ch. 399, Sec. 1, eff. Jan. 1, 1974. Amended by Acts 1975, 64th Leg., p. 913, ch. 342, Sec. 6, eff. Sept. 1, 1975. Acts 1993, 73rd Leg., ch. 900, Sec. 1.01, eff. Sept. 1, 1994.