Although cumbersome, sobriety checkpoints are one of law enforcement personnel’s most direct methods of monitoring for DUI offenders, as well as checking drivers’ licenses and vehicle registrations. States randomly use them, but most especially on peak celebratory holidays such as New Year’s Eve. Furthermore, because some courts and licensing authorities now issue restricted licenses to offenders, roadside checks allow officers to monitor compliance with court-ordered and statutory restrictions.
The primary purpose of DUI sobriety checkpoints is to promote the safety on the road for the general public and protect possible DUI offenders from the consequences of their own actions. Sobriety checkpoints appear to have become a favorite of law enforcement officials as they have increased in frequency on many public roads.
Sobriety checkpoints teeter on a delicate precipice between legitimate public safety and infringement upon a citizen's Fourth Amendment protection against unreasonable search and seizure. The issues that weighed in this precarious balance include the gravity of the public concerns served by the seizure, the degree to which the seizure advances the public interest and the severity of the interference with individual liberty. Many states consider sobriety checkpoints constitutionally valid, while others do not.
When a sobriety checkpoint is approved, courts generally find that it was conducted for the purpose of verifying compliance with DUI laws, and are thus a valid exercise of police power.
There are certain caveats in place, however. An officer who mans a sobriety checkpoint may not frisk a suspect as DUI offenses merely involve a possibly inhibited driver and not an actual weapon that would be found on a person. In fact, at court, if a frisk was performed, the officer must offer a factual basis for his suspicion that the driver was armed and dangerous.