How Long Can the Police Detain Me for a Traffic Stop?

You are pulled over by a police officer. He/she asks you a few questions, checks your information, and completes a traffic citation.
 
Are you free to leave?
 
The simple answer is yes; once the citation is complete you may leave. There is, however, no time limit to the citation procedure. There is no set amount of time prescribed to lawful detentions for traffic stops; the only requirement is that the officers allocate a "reasonable amount of time" to follow procedure. What is considered "reasonable" varies depending on the officer, situation, etc.
 
A detention becomes "unreasonable"—and therefore illegal—when you are held for an unnecessary length of time.
 
This point is reached when an officer has finished his/her investigation and does not have enough "reasonable suspicion" to keep you. The officer may prolong the investigation, but once it has been completed you are free to leave. The only way he/she can legally keep you at the scene is if:
     (1) You remain on the scene willingly
     (2) The police officer searches your vehicle 
 
Officers may only search your vehicle if they have "probable cause" to believe you are engaging in suspicious or illegal behavior. Probable cause requires evidence or facts that would lead a reasonable person to believe a crime has been committed; i.e. open liquor bottles, admission of guilt, smell of marijuana, etc. While the Fourth Amendment protects citizens from unlawful searches and seizures, many people are either unaware of this right or are unsure how to exercise it. If the police ask for permission to search your vehicle, you do not have to say yes. They are not legally permitted to search your car and keep you at the scene without your consent or probable cause.
 
Why does this matter?
 
Knowing your rights at a traffic-stop encounter is the best method of assuring that officers follow procedure. Traffic laws are meant to protect citizens, therefore one should not feel like he/she is being unnecessarily detained or unlawfully treated. While there is no set amount of time for traffic-stops, if you suspect that the process is unnecessarily long, you are permitted to ask the officer why you are being detained. If the citation has been completed, ask if you are free to leave. Educating yourself about your rights at a traffic stop prevents you from becoming a victim to intimidation, discrimination, etc.