I think the following typical news story speaks for itself:
DUI Checkpoint Nets 2 Citations, No Arrests Made
Costa Mesa, CA. June 27 - The Costa Mesa police ran a sobriety checkpoint Thursday at Santa Ana Avenue and 18th Street, citing two drivers and impounding two vehicles.
One driver was cited for driving on a suspended license. The other was cited for having vehicle registration that had expired more than six months ago.
During the process, 469 vehicles passed through and 410 drivers were screened. Twelve drivers were investigated for driving under the influence, but no arrests were made.
The Costa Mesa Police Department will join forces with Mothers Against Drunk Driving to conduct another checkpoint Aug. 15 at Wilson Street and Pomona Avenue. Patrolling officers will be set up on surrounding streets to stop impaired drivers from avoiding the sobriety screening.
The California Office of Traffic Safety funds the program through a grant as part of a national enforcement campaign.
See: Are DUI Roadblocks Effective?, Do DUI Roadblocks Work (Part II), DUI Sobriety Checkpoints for Fun and Profit, DUI Sobriety Checkpoints: Unconstitutional? and Police using DUI Roadblocks Illegally.