Police officers in New Jersey and elsewhere commonly tap or touch the rear taillight or trunk of a vehicle when approaching it during a traffic stop. This habit dates back decades. Originally, the “taillight tap” was performed to leave behind evidence of the encounter – specifically, the officer’s fingerprint – on the vehicle. For instance, a former New Jersey State Trooper explains that the tap “leaves fingerprint evidence on the glass of the taillight to prove that the officer was present at the scene”. If a stop later becomes a crime scene, investigators could match that print to the officer who was there. However, modern technology has changed the rationale for the practice. Today’s patrol cars usually have dashboard cameras and officers often wear body cameras, providing video proof of interactions. As a result, fingerprint evidence is less critical than it once was. Nevertheless, officers continue the tail-light tap for other practical reasons related to safety and tactics. In the sections below, we discuss three main reasons this practice persists: concerns for officer safety, establishing proof of contact with the vehicle, and the psychological impact on a driver.
Officer Safety and Precautionary Checks
A key reason officers tap a vehicle’s taillight or rear is safety. When approaching a stopped car, officers use the tap as a quick check. For example, the tap can verify that the trunk is securely closed – an unsecured trunk could hide an assailant or surprise a trooper. One Florida state trooper explains that the first reason to tap the rear is to make sure “no one is about to jump out of the trunk”. Law enforcement sources similarly note that an officer may touch the back of the vehicle “to make sure the trunk is latched” – ensuring nobody is hiding inside. In practice, officers often approach in pairs so that one taps the car while the other covers the driver’s side. This two-officer method maximizes protection against any sudden threat.
Evidence of Interaction and Documentation
Another rationale is documenting the stop itself. By touching the taillight or another part of the rear, an officer can leave fingerprints that link the officer to the vehicle. If the stop later becomes a crime scene investigation (for instance, if the driver flees or the officer is harmed), those prints serve as evidence that the officer was there. Criminal defense experts describe this as an old-fashioned way to “tag” the car. As one attorney explains, “leaving a thumbprint on the brake light is an old-school way to tag a car with a fingerprint,” tying the car to the stop if the officer is incapacitated. Similarly, police sources note that officers touch the rear of the vehicle “to prove that they were there” – leaving a trace that can identify the vehicle if the officer is attacked. These fingerprints provide a link between the officer and the stop in case of later investigations. (Today, patrol cars’ video cameras provide much of this documentation, but the fingerprint rationale still appears in many training descriptions.)
Psychological and Tactical Effects
A final reason for the taillight tap is psychological. The sudden tap or knock behind a vehicle is meant to startle the driver, disrupting any attempt to hide evidence. One law enforcement guide describes a scenario where passengers panicking to conceal contraband might freeze when the tap is heard, giving the officer time “to catch them in the act”. The driver’s startled reaction provides clues about suspicious behavior. Studies of this tactic note that surprise taps can significantly increase the likelihood of detecting illegal contraband. In effect, the brief jolt of a taillight tap gives the officer a split-second advantage, momentarily unnerving suspects and allowing better assessment of their actions. In short, the noise from the tap can slow a suspect’s movements and give the officer precious extra seconds to observe or respond.
Practice Across Different States
| State | Approach to Taillight Tapping |
|---|---|
| New Jersey | Common and traditional. NJ State Troopers are taught to tap the rear for safety and evidence. |
| Florida | Common practice. Florida officers routinely check that the trunk is closed and leave prints on taillights for evidence. |
| California | Generally discouraged. Many agencies advise against the tap because body/dash cams provide documentation; reliance on the tactic has declined. |
| Texas | No formal statewide policy. It was part of older training in many departments, but modern patrols often rely on cameras and reports instead. |
| New York | Historically used by state and local police, but now less emphasized. NY officers typically rely on video evidence and safe-approach tactics rather than routine taillight taps. |
The table shows that the taillight tap was once a widespread tactic, but its use varies today. In New Jersey and Florida it remains part of many officers’ routine (safety checks and evidence marking). In other states like California, agencies have formally discouraged the practice in favor of video recordings. Even in places where it isn’t outlawed, officers may view it as optional or outdated. (Training manuals and policies differ by department, so practices can vary even within a state.)
From Past Habits to Present Policies
In New Jersey and beyond, the tail-light tap remains a practiced tactic during traffic stops, rooted in officer safety and evidence. Originally used to leave behind proof of the officer’s presence (a fingerprint on the taillight), it also allows a quick trunk check to ensure safety. The noise of the tap can startle a suspect and slow any attempt to hide contraband, giving the officer a crucial moment to observe the occupants. Modern patrol vehicles now carry dashboard and body cameras, so fingerprints are no longer strictly necessary; in fact, many agencies today formally discourage tail-light tapping. Nonetheless, the practice persists in New Jersey due to training, habit, and ongoing safety considerations. If you experience this tap during a stop, it generally reflects standard police procedure rather than any special suspicion. Ultimately, the taillight tap is a simple, low-cost precaution that officers continue to use to protect themselves and document traffic stops.
