BAR=Bureau of Automotive Repair. they moniter all the repair shops in CA, and they also run the smog program. the check points are placed randomly across the state. if its an enhanced smog area, they bring out a dyno and smog the cars on dynos. basically the way the check point works is they have what appears to be a survery crew on the side of hte road, and therefore ge tto block off all lanes but one. this makes the cars file past a van with someone standing there looking at each car. if they see a car they want to check, they have a CHP officer get in front and make it pull off into a parking lot. you get out of teh car and they have BAR inspectors look all over it for modified parts that dont carry an EO. they then proceed to run a smog test on the car. if you see it and try to floor it past, they have CHP bikes waiting to pull you over. if they see something illegal, like no cats for example. or they detect that your cats are hollowed out(yes they can detect it), you get your $2500 per missing cat fine, so if you have an OffRoad pipe on your stang, you have a $10,000 fine. ive seen them do this mostly in the LA area, but they can do it anywhere in the state. they also have roadside infared gas analyzers, and if you pass the analyzer and are found to be emitting too high of a HC or CO or NOx level, or you are speeding, you get a letter from the DMW stating that you need to get your car smogged within usually 30 days.