KrisB:Not the case here. If you are trained in first aid and fail to act despite there being no other assistance around, you can be held liable. I think the rationale for it falls this way:
1. as a trained first responder (and human), you have a duty to act to save another human's life
2. by not responding, you breach that duty
3. this *caused* the patient to be delayed care
4. the damage could range from delayed recovery right up to death.
And I know you're thinking it -- "Canada, the next communist state" -- and you're probably right, given the political trends up here.
Perhaps this is the case in Canada, but with just a few states as the exception, that is not the case in the US. Being trained in First Aid (which we still consider layperson training) does not constitute a duty to act. The majority of states only *require* local Fire/EMS/Rescue/etc. people to respond. Case in point: I am a In-Charge Paramedic with Harris County Emergency Services District-1, we are responsible for ~100 sq miles of the northern unincorporated part of Harris County. I am responsible for my district when I am on duty and only then. If, while driving home, I see a accident in the City of Houston's district, I am under no legal requirement to stop and render aid and in fact many Medical Lawyers would recommend not stopping because of liability issues.