Here’s the basic scenario that probably puts a chill down any driver’s spine. You’re cruising down some unfamiliar stretch of highway and you’re not paying too much attention to your speedometer. The second after you pass a billboard, you notice that a police car is parked behind it, and the officer happens to have a radar gun pointed at you. The next thing you know, you’re being waved over and instructed to provide your driver’s license and vehicle registration. A few long minutes later, you drive off with an expensive speeding ticket tucked in your glove compartment.

WHAT IS A SPEED TRAP?

Getting caught in a speed trap — loosely defined as a spot where law enforcement officers are lying in wait to catch and ticket drivers exceeding the limit — can be a frustrating experience. And it’s probably not that uncommon. Getting pulled over for speeding is something that happens to nearly one in ten motorists each year, according to a survey released in 2013 by the National Highway Traffic Safety Administration. Those who were stopped say they received tickets 68 percent of the time, while 27 percent managed to get away with just a warning (another 5 percent didn’t get either). And depending upon the location, those who get cited can feel some serious financial pain. In New York state, for example, a speeding ticket could end up costing you more than $1,000, according to the Governor’s Traffic Safety Committee.

You might be thinking that this all seems unfair, and possibly illegal. How come police are able to conceal themselves and wait for unsuspecting speeders to fall into their snare? Isn’t setting a speed trap a form of entrapment? After all, the two terms sound so similar. Sorry to disappoint you, but don’t ever try that argument in traffic court.

“A speed trap is not entrapment because an officer is not inviting, enticing nor encouraging a driver to commit the offense of speeding,” To commit entrapment, they’d have to do something really outrageous — such as pull up alongside you in an unmarked vehicle, ask how fast your sports car can go and then challenge you to a race.

And that’s not just true in Georgia. Other states use the same definition of entrapment. Pennsylvania judge Jessica Brewbaker offers a similar explanation of what entrapment actually means in this 2014 PennLive.com column.

While nobody likes to get stopped for speeding, it’s not hard to understand the importance of enforcing speed limits. According to the National Highway Traffic Safety Administration, speeding was a factor in 27 percent of all fatal crashes in 2016, the most recent year for which data was available, and those accidents cost more than 10,000 people their lives.

That said, speed traps also have come under scrutiny in some places, where small towns have been accused of relying upon them as a money maker rather than to save lives. Garry Biller, president of the National Motorists Association, a Waunakee, Wisconsin-based advocacy group, explains that for decades, the convention in traffic engineering has been that speed limits should follow the 85th percentile rule. That means that the legal limit should be just a few miles per hour over the average speed of traffic on that particular stretch of road, which research has shown is the safest speed for drivers.

But that number isn’t necessarily permanent, since traffic flow can evolve over time. If there hasn’t been a recent traffic study, a situation can develop in which the posted speed limit actually is slower than the prevailing flow of traffic.

It’s hard to say exactly how any speed traps exist. In an effort to alert drivers to their presence, NMA has compiled a database of more than 80,000 user-submitted possible locations for speed traps in the U.S. and Canada. There also are some notorious historical examples, such as the small Florida towns of Lawtey and Waldo, where police used to write so many speeding tickets that in 1995, AAA officially designated both as “Traffic Traps” and even erected signs outside them to warn unwary drivers to slow down. (According to the Gainesville Sun and this AAA press release, the towns eventually changed their ways, and in 2018, AAA officially removed the designation.)

In recent years, some states have sought to discourage towns from operating speed traps by passing laws that limit the percentage of revenue that a town can derive from traffic tickets, according to this 2017 report from the National Conference of State Legislatures. Florida, for example, passed legislation in 2015 that requires a municipality or county to submit a report to a legislative auditing committee if total revenue from citations pays more than a third of a local law enforcement agency’s annual expenses. Georgia has a law that presumes that speed detection devices are being used for improper purposes if the resulting fines cover 40 percent or more of the agency’s budget. New York, Oklahoma and Texas have passed similar laws. Another state, Missouri, passed a law in 2015 requiring that all citation revenue exceeding 10 percent of operating expenses be turned over to the state to fund schools.