You couldn't be more correct! Out of hundreds of drivers, there are usually only a few arrests for DUI. Check out these recent stats from local police:
Originally Posted by Hyperbole
The Irvine Police Department conducted a sobriety/driverís license checkpoint during the evening hours on Saturday, December 17, 2005. The checkpoint was located on Mac Arthur Blvd. at Douglas in the city of Irvine. Here are the results of that checkpoint:
Total vehicles stopped: 337
DUI arrests: 2
Other arrests: 9
Vehicles Towed: 10
The Huntington Beach Police Department conducted a sobriety checkpoint on Saturday, June 10, 2006 from about 9:30 P.M. to 1:45 A.M.
More than 1300 vehicles passed through the checkpoint and about 400 vehicles were selected for screening. Of the 400 vehicles selected, three drivers were arrested for driving under the influence, eighteen were issued citations for driving without a license or for driving on a suspended license, and nineteen vehicles were impounded. Three people were cited for driving with an open container. Four others were arrested for possession of stolen property, possession of burglary tools, possession of marijuana, and for warrants.
The stats are in for the special checkpoint taskforce for Orange County for the two weeks before and including New Year's Eve 2005. A joint task force with the OC Sheriff's, Costa Mesa PD, and the Irvine PD held four checkpoints, as previously noted.
Out of 500 vehicle stops, there were 12 DUI arrests, 18 arrests for not having a license or having a suspended license, 4 warrants served, and 3 juveniles arrested for having prescription medications.
Like much of everything else in modern society, the explanation for why these continue is politics. MADD is one of the largest political action groups in the country, and they usually volunteer at each checkpoint, serving coffee and donuts, handing out MADD literature, and assisting with paperwork. In turn, the police receive DUI grant funding from the State and the Feds, as promised to MADD.
But it doesn't work, and it's the least effective way for the money to catch people DUI. It's just about keeping MADD busy, and happy.
Regarding your "random" comment, that's the only way that the U.S. Supreme Court has stated it's legal. Police either use a random number generator, or publish guidelines ahead of time, such as "every third car", to avoid the problem of stopping just people based on a certain race, type of car, etc. So the system, as designed, has to let certain people go to keep up the "random nature" of the stops.