In Newfoundland and Labrador, we have what is called An Act to Protect Persons Rendering Aid Following An Accident or in an Emergency. (The Emergency Medical Aid Act for short). This Act protects medical professionals and laypersons alike, absent gross negligence (serious mistakes).
As a layperson, the main criterion for protection is that you render aid “in respect of a person who is ill, injured or unconscious as the result of an accident or other emergency”.
As long as you render the first aid emergency assistance voluntarily and at the immediate scene of the accident or emergency you will be protected from liability. This means you will not be held legally responsible and thus will not have to pay “for injuries to or the death of that person alleged to have been caused by an act or omission on [your] part in rendering the medical services or first aid assistance, unless it is established that the injury or death was caused by gross negligence on [your] part.” Gross negligence is hard to define, but could be constituted by very markedly incompetent assistance, or an accumulation of negligent acts.
Courts will obviously be sympathetic to anyone who renders emergency assistance in good faith. One may wonder why this protection from suit is even thought to be necessary.