Tips for Protecting You from Law Enforcement Impersonators :
Those who impersonate police officers erode the publics trust in law enforcement and may endanger unsuspecting people. There are several tips you can remember to protect yourself during a traffic stop while helping your police officers do their jobs.
Make sure it is a marked police unit. If it is not a marked unit, the emergency lights should be built in and are usually not a temporary light placed on the vehicle.
Try to stop in a well-lit area or a location where there are a lot of people present.
Turn on your emergency flashers but dont turn off your car.
Do not get out of the vehicle to meet the officer. Officers usually dont like this anyway.
Lock your door.
Look for a uniform, official department jacket, and other equipment used by police officers for the performance of their duties.
If the officer is in plainclothes, look for identifying clothing and equipment. If unsure, explain to the officer that you are unsure about the situation and ask them to display official department identification and badge. Ask where they work and if you can contact their dispatch center to confirm their identity. You may also request a marked patrol unit respond.
Pay attention to what they are asking. Most officers will advise you of the reason for the stop and request your drivers license, registration, and proof of insurance.
If they immediately tell you to get out of the car without any preliminary questions, be suspicious.
Trust your instincts. If they dont seem to be a real police officer they are probably not.
from https://www.canbypolice.com/docs/police_impersonators.pdf with my emphasis