State and local protocols will determine what techniques and skills can and cannot be performed by EMS professionals (career and volunteer) for their level of training by a state agency (Public Health Department/Medical Board/EMS Department) that oversee standards and provides certification and/or licensing.

I could take a course where I learn a particular skill/procedure and the course provider/sponsor will attest (certify) that I have learned, tested and can perform the skill and the medical parameters for use, but unless the state and local protocols permit such use, I would practicing medicine beyond my scope of practice.

Good Samaritan Laws will generally only protect the individual from liability if they:
-Act in good faith
-Do not perform a skill/procedure beyond their recognized level of training – in this case the training would only be to the level for which the individual is recognized by the state has having. For example a military medic may perform on the battlefield, procedures which in the civilian world are not recognized within the scope of practice for a paramedic. If they were to perform that skill at an accident scene, the Good Samaritan Law would not shield them from civil and possibly criminal liability, especially if things went bad.

Pete