In cancer world this is why patients are instructed to print in large letters “AMBULANCE” on an envelope pasted to their fridge. It informs anyone coming to their house to not resuscitate . So likewise it Should be on neighbour to inform everyone of his DNR before calling a lawyer or laying any blame. You have no ability to see his chart as a bystander. He should own that. Nothing was stopping him from going around and informing his neighbours to not try to resuscitate. That’s on him.