I was driving near the border today and got pulled over by a border patrol agent while driving at speed limit. He alleged that I had exceeded the speed limit while passing a slow car (this may or may not be true, but that is besides the point of my question). I did not know that these federal agents had the power to stop people based on solely a state law violation (at least here in Arizona). This (http://cdn.ca9.uscourts.gov/datastore/opinions/2012/07/25/10-50249.pdf) sets the precedent that they can't but I wasn't going to bring up the legality of the stop until I had done some research. I respect what these guys do day in and day out but a state/traffic violation followed by threats of tickets and inspecting car registration and drivers license seem like an expansion of their designated role - which I am not for. What do you guys think?