They are required to show a badge at all times when in police uniform. They must be in police uniform if they are pulling you over as well. I know someone who was pulled over by someone who actually stole a cop car erlier that day. As rare as this is, it does happen. And if they've stolen a cop car and pulled you over, no good can come out of it. If you suspect this, i.e. someone not in uniform pulling you over. Call 911. When she got pulled over, the guy came up to her window and when she pulled out her cell phone and started calling someone she knew, he turned around and walked away and drove off. Also, if you are pulled over, never roll your window down more then about an inch to hand your id and registration through. Just enough so you can hear what they are saying and to slip your information through, that way the can not grab you. Keep your doors locked at all times too. If they order you to get out. Tell them you will not until they call for a second officer.