For those who would like to see more DUI enforcement, the Court of Criminal Appeals in Tennessee at Knoxville has affirmed that state law empowers citizens to arrest those driving under the influence of alcohol. See the opinion here: http://www.thenewspaper.com/rlc/docs/2015/tn-privatecop.pdf
Arresting power of private citizens includes misdemeanors in addition to felonies. Most of us have had police officers blow past us at high rates of speed that far exceed the posted speed limit without having their lights on. I once witnessed an officer put his lights on to go though an intersection and then turn his lights off after he got through the intersection.
Minor traffic offenses are usually handled with a citation in lieu of arrest but more serious violations usually result in arrest. I wonder what would happen if private citizens started exercising this power to arrest officers for all the traffic violations that they commit in public. An officer once told me that courts frown on it, but what’s good for the goose is good for the gander.