For a cop to pull someone over, probable cause must exist. The police officer needs to have a valid reason to believe there is a violation of the law that requires investigation.
While law enforcement often investigates drivers, there are only a limited number of scenarios in which the authorities have probable cause for stopping someone.
Traffic offenses
The most straightforward reason for an officer to stop a vehicle is seeing a breach of traffic laws. Common infractions include speeding, running a red light, not using turn signals, failing to yield and making an illegal turn.
Equipment violations
Any vehicle that does not meet the legal standard for roadworthiness is eligible for a pullover. Breaches can be malfunctioning lights, a missing license plate or a cracked windshield. Less obvious reasons, such as expired registration tags, also give the police a valid justification for making a stop.
Erratic driving
Improper driving can prompt a police officer to pull a vehicle over on suspicion of more serious offenses, such as driving under the influence. Wild swerves, inconsistent speed and abrupt stops are driving behaviors that create probable cause.
Inside information
Sometimes, police receive a tip from a reliable source that forms the basis of probable cause. It could be knowledge about a stolen vehicle or a description of one in connection with a recent crime. If the information is credible and detailed, it can justify a traffic stop.
Checkpoints
Sometimes, police are authorized to set up checkpoints for specific purposes, such as checking for drunk drivers or ensuring compliance with registration and emissions requirements. The reason for the checkpoint itself establishes probable cause.
Understanding why police officers have the right to stop drivers can make these roadside interactions less stressful. Equally important, when a commuter faces charges from a pullover where probable cause does not exist, it can form the basis of an effective defense.