At a checkpoint site, police directed all traffic headed in one direction to a roadside area where officers checked motorists for signs of intoxication.
If there was no immediate evidence of intoxication, the motorist was given atraffic safety brochure and allowed to drive away.The average delay was about 30 seconds.
If signs of intoxication were detected, adriver was directed to another area for furtherquestioning and perhaps a breath test.
At one such checkpoint, Michigan state policetroopers checked 126 vehicles in less than an hourand detained two drivers for sobriety field tests.One driver was arrested on drunken-drivingcharges.
The state police department was sued soon afterthe checkpoint program began. The lawsuit allegedthat the checkpoints violated the FourthAmendment's ban on unreasonable police searchesand seizures.
State courts banned the checkpoints, citing"the potential for an unreasonable, subjectiveintrusion on individual liberty interests."
In defending the checkpoint program, MichiganAttorney General Frank Kelley told the justicesthat fighting drunken driving is a "grave andlegitimate public interest."
He said Michigan's checkpoint program is valideven if it is not the most effective policeprocedure or may carry the "potential ofgenerating fear and surprise in some motorists."
Lawyers for those who successfully challengedthe checkpoint program urged the justices toreject the appeal.
They said the "warrantless, suspicionlessseizure" of a vehicle at a sobriety checkpointcould lead to drivers and passengers beingrequired to get out and being subjected to patdownsearches. They said police officers may use suchoccasions to inspect a vehicle's contents.
In other matters, the Court:
. Agreed to use a Florida case to decidewhether states may prohibit grand jury witnessesfrom making public their own testimony once theinvestigation has ended.
. Said it will decide whether the governmentmay prohibit soliciting on all Postal Serviceproperty, including the sidewalks adjacent to postoffice buildings.
. Left intact a $278,000 libel award against aPawtucket, R.I., newspaper by refusing to review aruling that news stories may be libelous even ifthey contain no false statement