MONTREAL—Quebec’s new “Move Over” law came into effect on Sunday, confronting the province’s motorists with new rules limiting how they can drive around emergency vehicles.

The law is simple: all drivers must slow down when they see an emergency vehicle and change lanes to give responders extra space. Anyone caught flouting the rules will face a fine of up to $300 and lose up to four demerit points.

A variant of the law has already been adopted by most Canadian provinces and many U.S. states. The law was passed in Quebec after a number of first responders were killed by motorist not giving a proper buffer to emergency crews.

Since 2008, four Surete du Quebec officers have been killed in roadside accidents.