A traffic stop of a vehicle and detention of its occupants is a seizure for Fourth Amendment purposes. A routine traffic stop is justified if the police officer has a reasonable suspicion that the occupant is unlicensed or the vehicle is unregistered. The officer does not need a reasonable suspicion of the occupant’s involvement in criminal activities. The reasonable suspicion of criminal activities discovered during the traffic stop may give rise to a legitimate terry stop.
State statutes can provide legitimate grounds for traffic stop checks that involve less arbitrary intrusion and do not fall within Fourth Amendment searches and seizures. Reasonable suspicion is therefore unnecessary in these situations.
Moreover, some state cases established that a traffic stop conducted by government officials other than police officers might be legitimate as well if the officials have reasonable suspicion of some violation of law.