We are an independent, advertising-supported comparison service. Our goal is to help you make smarter financial decisions by providing you with interactive tools and financial calculators, publishing original and objective content, by enabling you to conduct research and compare information for free – so that you can make financial decisions with confidence. The offers that appear on this site are from companies from which TheSimpleDollar.com receives compensation. This compensation may impact how and where products appear on this site including, for example, the order in which they appear. The Simple Dollar does not include all card/financial services companies or all card/financial services offers available in the marketplace. The Simple Dollar has partnerships with issuers including, but not limited to, Capital One, Chase & Discover. View our full advertiser disclosure to learn more.
Are Radar Detectors Legal and How Do They Work?
Would you drive above the speed limit if you knew you wouldn’t get caught? For many, investing in a radar detector allows them to do just that — even though we obviously don’t recommend speeding. The cop detector industry is expected to be valued at $20.6 billion by 2023, so as you can imagine, there are many radar detector options on the market.
We take a deep dive into everything you should know about radar detectors, including how they work and if they’re legal.
Must-know car radar detector definitions
To understand how radar detectors work, it’s important to first know the difference between devices and the language used around them.
What are radar detectors?
Radar detectors are small devices that drivers install in their cars to detect the presence of radar, which is used by law enforcement to detect the speed of cars. When a radar detector detects radio waves emitted by a radar gun, it will alert the driver. It’s used to warn drivers to adjust their speed if it’s being measured by a police officer nearby.
Do radar detectors work?
It’s relative whether radar detectors work. It depends on the type of device you use and the device the law officer is using. As technology advances, there is a push and pull between the radars and the detectors. For example, speed cameras can only be detected by radar detectors that are in the 4-star or 5-star category. Although it’s considered outdated in most of the U.S., some police radar guns still operate using X band radar.
How do radar detectors work?
For radar detectors to work, there needs to be a radar in the vicinity. We’ll walk through how a radar detector works, starting with how it’s triggered — the radar gun.
The police officer points the radar gun at the road they are checking speeds and can determine the speed of every vehicle that passes.
This process happens at lightning speed, so it appears nearly immediate to the police office tracking your speed.
This is where the radar detector can help. A driver is able to detect if law enforcement is using a radar device if they have a radar detector installed in their car.
If a police officer pulls up behind you and then turns on their radar gun, the radio detector will not help, since the police officer has already collected your speed.
Avoid a speeding ticket by slowing down before a police officer catches your radar reading.
Radar detector laws
Radar detectors are nothing new. In fact, they’ve been around since 1968. However, the legislation around them has evolved over the years.
The legislation around owning a radar detector is determined on the state level with almost every state permitting passenger vehicles to have radar detectors. The only states and districts that don’t allow radar detectors are Washington D.C. and Virginia. However, every state doesn’t allow commercial vehicles to use radar detectors due to the U.S. Department of Transportation law prohibiting it.
Owning a radar jammer, or a device that interferes with law enforcement radar guns and blocks police from getting an accurate reading, is a whole different story. While there are nine states that have made it illegal to own a radar jammer, there can be harsh repercussions for using one in any state in the U.S.
For some background, The Federal Communications Commission (FCC) has banned the operation, marketing, or sale of any type of jamming equipment due to safety risks. That’s why you don’t see radar jammers in advertisements or stocked on the shelves of retailers.
So, what’s the consequence for getting caught using a radar jammer?
If you get caught using one on a federal interstate, regardless of state, there are harsh penalties — up to a $50,000 fine and/or five years in prison. As for getting caught for using them outside of federal roads, there are 9 states that have made radar jammers illegal: California, Colorado, Illinois, Minnesota, Nebraska, Oklahoma, South Carolina, Tennessee, Virginia and Washington D.C.
Types of radar detectors
Before making a purchase, you’ll want to decide which of the two types of radar detectors you want — a dash-mounted radar detector or remote radar detector.
A dash- or window-mounted radar detector is secured by suction cups and can be moved from one car to another. This can be a great option for those who want to share the device or transfer it to a rental car temporarily.
Remote radar detectors are hidden and are built directly into your car. While the dash-mounted radar detector has all parts in one unit, the remote radar detector has the antenna, speakers and displayed in different places in the car so that it’s integrated into the vehicle. Drivers typically opt for a remote radar detector if they don’t want police officers to see it and to avoid theft.
Do radar detectors work with speed cameras?
Many police agencies have started to replace police officer speed traps with speed cameras, which are a lightweight, easy-to-install and cost effective way to catch speeders. Speed cameras take a picture of your vehicle if you’re driving above the speed limit, ultimately capturing the color, make and model of your vehicle, and license plate. A violation is sent to your home address thereafter.
Speed cameras operate using a low power K band or Ka band. Let’s dive into the difference between each type of band and how it relates to radar detectors.
What is a Ka band?
This is the most modern type of radar band frequency on the market used by law enforcement today. Ka bands operate on radio waves between 33.4 GHz and 36.0 GHz. The high frequencies make it more difficult for radar detectors to detect it unless it’s a highly-rated, newer device. If a radar detector picks up a Ka band, it’s likely law enforcement as it’s unusual for other devices to emit the frequency.
What is a K band?
K band is a level below Ka bands operating on radio waves between 18 GHz and 27 GHz. Radar guns operating on K bands make it more difficult for radar detectors to detect the frequency from a far distance making high-quality radar detectors important for drivers to be warned.
What is an X band?
X band is the lowest level of radio waves operating between 8.0 GHz and 12 GHz. This type of radio wave is mostly phased out in the U.S., but some rural areas and some states, such as Ohio and New Jersey, are known to have law enforcement still using the X band.
Do your research and consult with an expert before investing in a radar detector if you want it to detect speed cameras.
Are radar detectors worth it?
The best advice we found to avoid getting caught for speeding is: “Don’t speed.” We know, not quite what you’re looking for however, weigh the possibility of getting caught with a radar detector or radar jammer (if you’re in a state where it’s illegal) to decide if it’s worth installing one in your car.
Download our infographic for a snapshot of the mechanics of radar detectors.