In 1968, the U.S. Supreme Court provided some guidelines for detention without arrest in its decision in Terry vs. Ohio. Under these, police officers may appropriately detain a person for investigation even without probable cause to arrest when they reasonably believe that criminal activity has occurred, is occurring, or is about to occur. The stop and frisk rationale has been applied to detaining pedestrians in the streets and persons in building and apartments if detaining officers can articulate facts that justify their belief that criminal activity is afoot. More recently, courts have applied the Terry principle to detention of motorists and of luggage. While courts have not placed definite time limits on the duration of such detention, they generally consider the purpose of the detention and police efforts to confirm or dispel their suspicions. While police cannot stop automobiles routinely to check driver's licenses and registrations, automobiles may be detained on the basis of articulable and reasonable suspicion. Courts also have approved the use of roadblocks and checkpoints to determine if drivers are properly credentialed. The rationale for roadblock stops is that because of visible signs of police authority, motorists are less likely to be frightened or annoyed by the intrusion. 17 footnotes.