Why Does a Policeman Touch a Tail Light?

By Jayne Thompson - Updated March 15, 2018
Car Rear Tail Light

When police officers perform routine actions like touching your tail light, it can make you feel extremely nervous. You may be wondering if your vehicle is damaged or if the officer is extra-suspicious of you because you have done something seriously wrong. The goods news is, tapping the tail light has very little to do with the reason why you were stopped. It's more about protecting the police officer than incriminating you.


A cop touches your tail light to leave fingerprint evidence in case she needs to prove that a stop occurred. It's also a safety precaution, since it's generally safer to approach from the side of the vehicle than from the rear.

Touching the Car Proves the Stop Occurred

When a police officer touches your tail light or bumper, she leaves fingerprint and DNA evidence behind. This provides critical evidence so investigators can place the vehicle and its owner at the scene in case you try to flee. Tapping the tail light establishes a physical connection between the vehicle and the police officer, which is especially relevant if the police officer is attacked or injured during a routine stop.

It's a Safety Precaution

If you're wondering why cops touch specifically the tail light and not, for example, the trunk, it's because tapping the tail light keeps the police officer to the side of the vehicle and not directly behind it. This keeps the officer out of harm's way should the driver start to back up. Approaching from the side is also the best position for the officer to see into the driver's lap area and the back seat to assess whether any weapons are visible. This is especially relevant for one-officer patrol units when there's no second officer to maintain a safety watch on the occupants of the vehicle.

Cops Can Spot Evidence in Plain View

It's not unusual for people to try to hide illegal drugs or weapons after they have been pulled over. Tapping the back of a car helps to distract criminals and stop them hiding something they should not have. Generally, a police officer can only search a car if you consent, or if the officer sees suspicious items hiding in plain view. So, if the police officer distracts you before you have time to stash the goods, the police can seize the items and conduct a more thorough search. The police report an increase in arrest rates for intoxicated drivers and those found to be in possession of prohibited substances and unlicensed firearms when tail light tapping techniques are used.

Old Habits Die Hard

Today, a police officer may tap your tail lights for no other reason than habit. There are traffic cameras all over most city streets, and most law enforcement vehicles now come fully equipped with cameras and other technology that proves the police officer was present at the scene. So, touching the tail light is really an unnecessary step. There's also an argument that tapping the vehicle exposes the police officer's location, making him more vulnerable to attack. For these reasons, some police departments now discourage police officers from tail light tapping.

About the Author

Jayne Thompson earned an LLB in Law and Business Administration from the University of Birmingham and an LLM in International Law from the University of East London. She practiced in various “big law” firms before launching a career as a commercial writer. Her work has appeared on numerous legal blogs including Quittance, Upcounsel and Medical Negligence Experts. Find her at www.whiterosecopywriting.com.

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