Emergency Response:

§ 74.151.

(a) A person who in good faith administers emergency care, including using an automated external defibrillator, is not liable in civil damages for an act performed during the emergency unless the act is willfully or wantonly negligent.

(b) This section does not apply to care administered:

(1) for or in expectation of remuneration, provided that being legally entitled to receive remuneration for the emergency care rendered shall not determine whether or not the care was administered for or in anticipation of remuneration; or

(2) by a person who was at the scene of the emergency because he or a person he represents as an agent was soliciting business or seeking to perform a service for remuneration.

(e) This section does not apply to a person whose negligent act or omission was a producing cause of the emergency for which care is being administered.

Automatic External Defibrillator:

Sec. 779.006.

The prescribing physician who authorizes the acquisition of an automated external defibrillator in accordance with this chapter, a person or entity that provides approved training in the use of an automated external defibrillator in accordance with this chapter, and the person or entity that acquires the automated external defibrillator and meets the requirements of this chapter are not liable for civil damages for such prescription, training, or acquisition unless the conduct is willfully or wantonly negligent. Any person or entity that acquires an automated external defibrillator and negligently fails to comply with the requirements of this chapter is liable for civil damages caused by such negligence.

http://www.statutes.legis.state.tx.us/Docs/CP/htm/CP.74.htm

http://www.statutes.legis.state.tx.us/Docs/HS/htm/HS.779.htm