Not being an attorney, I can't tell you what all the legal issues are, but as an EMS instructor we teach the doctrine of "Duty to Act". This means that if you have a duty to respond to emergencies as a part of your job, then you must respond while you are working. There generally is no duty to act when off duty. If you choose to act when you don't have the duty to, then you provide care to the best of your ability and training level until relieved by someone of equal or higher training, just as you would while on duty. It seems the question hinges on whether or not you workplace policy mandates that you respond to emergencies while at work. I would definitely seek the advice of an attorney that is familiar with the laws on this issue in your area. Best of luck--I hope everything works out for you.