So you were driving down the highway the other day when you noticed a police officer up ahead. You were both driving a bit fast, so you figured there was no way the officer would pick on you. But after a mile the cruiser let you pass, then pulled you over. Sounds far fetched? Nope, it can happen through the “pacing” loophole.

To charge you with a speeding ticket, a police officer needs to collect evidence that you were, well, speeding. Most of the time this evidence comes from radar. Some advanced departments use a laser system called LIDAR. But these systems require the police officer be parked with the scanning device already fired up. If they are driving and see a car speeding down the road they only have one good option: to pace the speeder.

“Pacing” simply means keeping pace with another car long enough to get evidence it was speeding. It can be a handy loophole for a moving police officer to get around the limitations of radar or laser systems. The police cruiser can be either in front or behind the suspect. But this method provides the least reliable evidence. Some lawyers estimate they can beat 80% of “pacing” speeding tickets in court.

What are the problems with pacing? Well by definition the police cruiser needs to be going the exact same speed as the suspect’s vehicle. On rough pavement or around corners, that’s nearly impossible. Even on straight pavement, it means the cruiser and the suspect’s car can’t be getting closer or further from one another. Even for a trained police officer to know they are holding the pace, they need to be pretty close to the other car with excellent visibility.

In addition, some states have a minimum distance the police officer must pace a speeder. This might be 1/8 of a mile. This might even be 1/4 of a mile. In a downtown area, they often hit a stop sign or signal before getting sufficient evidence.

How does a lawyer get a “pacing” speeding ticket dismissed? By demonstrating the evidence is incomplete. Perhaps the police officer didn’t keep pace with the suspect for long enough. Or perhaps the road was curved or broken, preventing either vehicle from maintaining a constant speed. Maybe visibility was poor. Or maybe the police officer was actually driving at a different pace and whichever vehicle was behind was slowly catching up.

In rare cases, police departments don’t have recent evidence that their cruisers’ speedometers are properly calibrated and a pacing ticket gets tossed. But most departments check speedometers regularly, for exactly this reason.

Hiring a lawyer to fight a pacing ticket in court is not a cheap venture. So if you do see a police officer in front of you–or following close behind you–it’s always best to just slow down so you know for sure you aren’t speeding and they can’t hit you with a “pacing” ticket.

Next, find out why police don’t need a warrant to search your car with the ‘cat’s out of the bag’ loophole, or see how to fight a pacing ticket in the video below: