Thanks Pace. You are correct - it is a minefield. Just as EASA can ruin your life by piling on stupid red tape, so can coroners and others in strange and not so strange countries. Not so long ago we had an elderly cancer patient who not unexpectedly died on the way home to die. If she had died in Spanish airspace the aircraft would have been impounded for a week.......
That being said, most countries do not hold aircrew responsible for fly: no fly decisions. The commander is responsible for the safety of the medical equipment and it is interesting how many pilots allow freestanding electronic kit on board. I remember on a CAA final check ride after modifying am aircraft for air ambulance work we fired up a defibrillator established on 5 mile finals. Luckily it was a dummy run and CAVOK.
I agree I would always help, but one thing to bear in mind is that US paramedics and hospitals sometimes have a jaundiced view that any non US healthcare worker is slightly inferior. If they complain to homeland security there is a possibility you may not be leaving the same day. That is why some air ambulance companies fly anywhere including warzones but not the US....