I have a question for a paper I am writing. I've tried researching this but haven't come up with an answer.

Can somebody tell me, are federal agents or members of federal law enforcment agencies, such as the ATF, FBI or USMS empowered to conduct traffic stops. When I say traffic stop I mean stopping a vehicle for a reason other than a traffic violation (eg wanted felon, crime recently comitted etc).

If so, under what authority do they do this? State Law, Federal Law? Or do they use local law enforcement to do so.

Thanks