Unconstitutional checkpoint in Sonoma on July 4th

2013-07-06 "Over three dozen arrested at DUI checkpoint in Sonoma County"
from "Bay City News" [http://abclocal.go.com/kgo/story?section=news/local/north_bay&id=9164010]:
SANTA ROSA, Calif. -- A Sonoma County DUI task force stopped more than 1,000 vehicles Friday night in Santa Rosa and arrested 55 drivers, including 47 on suspicion of driving without a license, a spokesman said.
The county task force, made up of the Sonoma County Sheriff's Office and a dozen local police departments, made the arrests at a DUI checkpoint in downtown Santa Rosa, Petaluma police Officer Walter Spiller said.
The checkpoint, set up during the Fourth of July holiday weekend period, targeted northbound drivers on Morgan Street south of 5th Street next to U.S. Highway 101, Spiller said.
Officers stopped the drivers of 1,027 cars between 6 p.m. and midnight Friday to check for those who appeared impaired or were driving with a suspended license or without a license, Spiller said.
From the vehicles, police screened 889 drivers for signs of DUI and for valid licenses and diverted 92 drivers to a parking lot for further investigation, Spiller said.
Only one person was arrested on suspicion of DUI while 47 were arrested on suspicion of driving without a license and seven on suspicion of driving with a suspended license, Spiller said.
Task force officers had nine vehicles towed from the checkpoint and five vehicles impounded for 30 days, Spiller said.