Valerie eventually got the fine reduced to $115. She was quoted as saying, "What's an emergency vehicle, anyway?" Do you think it is obvious that a police car with its lights on is an emergency vehicle? Ambulances and firetrucks would be the other obvious vehicles that qualify.
We personally hate it when cars don't slow down, stop at lights (even when green) and pull over for ambulances, fire trucks and police cars en route. We bet if their loved one were waiting for that ambulance, they would want everyone to pull over or else be fined $632 Canadian dollars.
[Source: Calgary Pundit (warning: some bad language)]