190.092 R.S.Mo. 4
Liability: Use of an AED
An individual, who, in good faith and voluntarily, provides emergency care through the use of an AED will not be held legally responsible for acting or failing to act. They can be held legally responsible if acting with extreme carelessness or intent to cause harm. This section includes the person who provides training on the use of an AED, and the physician that reviews and approves clinical protocol regarding the AED.
Defibrillators, use authorized when, conditions, notice - good faith immunity from civil liability, when
4. Any person who gratuitously and in good faith renders emergency care by use of or provision of an automated external defibrillator shall not be held liable for any civil damages as a result of such care or treatment, unless the person acts in a willful and wanton or reckless manner in providing the care, advice, or assistance. The person or entity who provides appropriate training to the person using an automated external defibrillator, the person or entity responsible for the site where the automated external defibrillator is located, the person or entity that owns the automated external defibrillator, the person or entity that provided clinical protocol for automated external defibrillator sites or programs, and the licensed physician who reviews and approves the clinical protocol shall likewise not be held liable for civil damages resulting from the use of an automated external defibrillator. Nothing in this section shall affect any claims brought pursuant to chapter 537 or 538.