Emergency Response:

TITLE 76 §76-5

(2)  Where no prior contractual relationship exists, any person who in good faith renders or attempts to render emergency care consisting of artificial respiration, restoration of breathing, or preventing or retarding the loss of blood, or aiding or restoring heart action or circulation of blood to the victim or victims of an accident or emergency, wherever required, shall not be liable for any civil damages as a result of any acts or omissions by such person in rendering the emergency care.

Automatic External Defibrillator:

TITLE 75 §75-5A

Section 5A.  A.  1.  Any person who is qualified pursuant to this subsection and who, in good faith and without expectation of compensation, renders emergency care or treatment outside of a medical facility by the use of an automated external defibrillator shall be immune from civil liability for personal injury which results from the use of the device, except for acts of gross negligence or willful or wanton misconduct in the use of such device.

http://www.oklegislature.gov/osstatuestitle.html