A lot depends on how traffic law enforcement is allocated. In some states only state troopers enforce traffic laws on the interstate, sheriff on county roads and local police on city streets. In other states, any LEO can cite you on any road within their jurisdiction.
There was recent case on the news where a LFO arrived on the sceen of an accident and rendered aid but refused to do a breathalizer test on a driver. It was over a half hour later before another LFO arrived that had jurisdiction to perform the breathalizer test.
