Seeing a vehicle with flashing green lights can be confusing because most drivers associate emergency vehicles with red, blue, or amber. The important thing to know is that green lights do not have one universal meaning—their use depends heavily on local laws.
In many areas, particularly parts of the United States and Canada, flashing green lights can identify volunteer firefighters or other emergency responders traveling in their personal vehicles to a station or emergency scene. The lights are intended to alert other motorists that the driver is responding to something urgent.
However, these green lights are often considered courtesy lights, not the same as the emergency lights on a marked ambulance, police car, or fire engine. In many jurisdictions, the volunteer responder must still obey ordinary traffic laws, and other drivers may not be legally required to pull over.
Green lights can have other authorized uses as well. Depending on the jurisdiction, they may appear on command vehicles at emergency scenes, certain transportation vehicles, or other specialized services.
So what should you do? If you see a vehicle approaching with flashing green lights, do not panic or make a sudden maneuver. Slow down, remain predictable, and when it is safe and lawful, give the vehicle room to pass.
The officer mentioned in the image may have been referring to a local rule where green lights identify authorized responders. Because the rules vary so widely, drivers should check their own state, province, or country’s traffic regulations rather than assuming green always means the same thing.