An on-duty police officer patrolling the streets may pull a vehicle over when the situation warrants a traffic stop. A traffic stop cannot be performed randomly and the officer must have justification prior to stopping the vehicle. Reasons law enforcement can stop a vehicle include observance of a moving violation or vehicle equipment violation and reasonable suspicion of criminal activity. Law enforcement also has the right to check a license plate against the police department's database for stolen vehicles or active arrest warrants.
A police officer who witnesses a driver committing a moving violation may perform a traffic stop. Moving violations include speeding, passing through a red light or stop sign without stopping, failure to signal a turn, failure to yield the right of way and driving on the wrong side of the road. Observance of equipment violations, such as a defective turn signal, brake light or headlight, also warrants a traffic stop. Observance of a vehicle bearing an out of date registration or inspection sticker can result in a stop. If a police officer determines that any passenger of the vehicle is not wearing a seat belt or that a child is not secured properly in an age-appropriate safety seat, the operator may be stopped and issued a citation.
A law enforcement official may stop a vehicle operating on the roadway if there is reasonable suspicion of criminal activity such as driving while under the influence of drugs or alcohol. Reasonable suspicion must be a result of observed behavior and visible facts in addition to the officer's discretion. Weaving or drifting in and out of lanes, following too closely to the preceding vehicle and driving significantly below the speed limit are all indications that a driver is operating with impaired judgment and motor skills. Where reasonable suspicion is present, the officer must pull the vehicle over to conduct further investigation.
License Plate Check
Police can report the license plate number of any vehicle to dispatch and find out if the plate number is associated with a stolen vehicle report. The officer also has access to information regarding the vehicle owner, including license suspension and open arrest warrants. Law enforcement officials may perform a traffic stop on a vehicle if the vehicle has been reported stolen or if the operator bears resemblance to the physical description of the vehicle owner. Several Supreme Court rulings conclude that Fourth Amendment rights to privacy do not apply to license plates and that traffic stops are allowed when a check on the license plate creates reasonable suspicion.