What is required to stop a vehicle legally?

To stop a vehicle legally, articulable suspicion is required. This legal standard means that a law enforcement officer must have a specific and explainable reason to suspect that a traffic violation or crime is occurring. This does not require absolute certainty or proof of a crime, but there must be observable facts that, when considered together, lead the officer to believe that a violation may be taking place.

Having articulable suspicion allows the officer to initiate a stop without the need for a warrant or the higher standard of probable cause that would be necessary for an arrest. This concept is rooted in the Fourth Amendment, which protects against unreasonable searches and seizures, allowing law enforcement to efficiently ensure public safety while adhering to constitutional guidelines.

In contrast, other options do not meet the legal threshold required for a lawful stop. Certainty of violation is not necessary since officers must only suspect that a violation could be occurring. A written warning would not justify initiating a stop; it serves more as a tool for post-stop documentation. Communicative interaction, while important for explaining the stop and fostering cooperation, does not itself provide the legal basis needed to initiate that stop.