A decision made late last month in Delta, B.C., to allow firefighters to give pain medication and maintain IVs during emergencies comes into effect on Monday.
B.C. Emergency Health Services says the move is illegal because it violates provincial law.
The paramedics' union also opposes the decision and says the underlying issue is a lack of resources for paramedics.
Delta Mayor Lois Jackson says fire responders are often the first to arrive on scene and that allowing them more medical authority will improve emergency service.
Delta Fire Chief Dan Copeland says crews have been trained and lawyers consulted for the program's Monday roll-out.