Next time you get pulled over, in between frantically shuffling through the Wendy’s napkins and totally-still-in-date insurance paperwork in your glove box, take a look in your mirror as the cop walks up. You might see them tap your tail light on their way up to ask for your license and registration. But why do cops do that?
It’s not just because they like touching things they’re not supposed to be touching. In fact, when the practice began, its reasoning was almost reasonable. Now, though, times have changed — and so has the reason why cops touch your tail light.
Back in the day, cops used to touch the tail lights of cars they pulled over in order to leave fingerprints as evidence. Reader’s Digest spoke with experts who said that the practice marked a car in case the stop went wrong — leaving evidence that the officer had been there:
According to Nick Fresolone, a retired police-academy instructor with the New Jersey State Police Academy in Sea Girt, New Jersey, the “taillight tap” leaves fingerprint evidence on the glass of the taillight to prove that the officer was present at the scene. Ultimately, says Fresolone, if things escalate or otherwise go awry, the officer’s touch to the car’s taillight will have left a fingerprint in a place where investigators would know to look for it.
Criminal defense attorney Joe Hoelscher says that this routine maneuver serves as a sort of breadcrumb left to prove that the police officer had approached that particular vehicle. “Leaving a thumbprint on the brake light is an old-school way to tag a car with a fingerprint, so it can be identified conclusively as the vehicle involved in a stop should the officer become incapacitated,” explains Hoelscher.
Now, though, things are a little bit different. The advent of dash cams and body cams has of course been the major change, allowing cops to forego the smudged fingerprint in favor of video evidence showing the car, its license plate, the officer, and the whole altercation. But there’s another reason why fingerprints are no longer the reason cops touch your car: It turns out fingerprint analysis isn’t all it’s cracked up to be.
Studies have shown that fingerprint evidence really shouldn’t be relied upon in court, because it’s just so difficult to match two prints to each other with perfect accuracy. Worse still, we collectively realized that no one’s ever even proven that fingerprints are unique. If these things can’t be done perfectly under controlled conditions in a lab, how will that analysis fare on a tail light that’s been exposed to the elements?
No, in the modern era, the reason cops tap your car is entirely different. Now, according to The Law Dictionary, a primary reason is just to put the fear of god in you:
Inevitably, police officers are going to run into unsafe situations when they pull people over. Sometimes drivers will have illegal substances or prohibited items in their cars like guns, ammunition, or drugs. Naturally, if the driver does have something illegal in the vehicle, he or she will want to hide it before the officer approaches the window.
So, one of the reasons why cops touch tail lights is to startle the person inside. The driver is likely not expecting the noise of the tap, which typically causes him or her to stop for a moment, giving the police officer additional time to witness what the driver is trying to hide (if there is anything).
Studies have shown that police stops correlate with higher levels of post-traumatic stress disorder in adults, and cops complain that they’re too stressed out from their beats. Clearly the solution here is to add more anxiety all around, just in case that driver you caught doing 15 over the limit is hiding Jimmy Hoffa in their glove box. Or, as The Law Dictionary goes on to explain, hiding other folks in other places:
Police officers put their lives at risk everyday on the job and must be prepared for danger and violence to arise at any moment. While tapping a tail light may startle a driver and leave evidence on the vehicle, there is another tactic cops use. If the police officer believes they are in a dangerous situation as they pull you over, they may touch the backend of your vehicle on the way to your window to make sure the trunk is latched. It might sound bizarre, but this tactic ensures that no one is hiding in the trunk and could pop out.
If a police officer does check that your trunk is shut, they will typically have their partner with them. One officer will check the trunk, while the other approaches your window. This is to ensure the safety of the officers and make sure the driver is not able to get away with hiding anything or obtaining a weapon while the officer is checking the trunk.
The reason cops tap the back of your car is fear, be it theirs or yours. Cops — the 22nd deadliest job in America, sitting below garbage collectors and UPS drivers but above maintenance workers — live in fear, thinking something’s always out to get them. They tap the back of your car to check for monsters under the bed, and to instill in you a bit of the fear they carry with them every day. If that’s not protecting and serving, I don’t know what is.