Tennessee Radar Detectors Are Legal, Jammers Are a Crime

Tennessee's radar law is built around interference, not detection. Searching the whole Tennessee Code for "radar" returns six sections, and it is worth naming them because the absence is the answer: § 24-7-124 governs the admissibility of results from radar, laser or similar speed-measuring devices; § 55-8-153 covers the establishment of speed zones; § 65-17-105 and § 47-18-104 are utility and consumer-protection provisions; and the only two that reach equipment in a private car are § 39-16-610 on jamming devices and § 39-17-113 on paying the citations of people who bought them. No section regulates a device that merely receives. There is no registration, no prohibition on mounting one, and no separate rule for the windshield.

Section 39-16-610 is deliberately broad about what counts as a jammer. Subdivision (a)(1) reaches "any active or passive device, instrument, mechanism, or equipment that is designed or intended to interfere with, disrupt, or scramble the radar or laser that is used by law enforcement agencies and officers to measure the speed of motor vehicles," and (a)(2) confirms it captures what the market calls jammers and scramblers. The word "laser" matters: a lidar jammer is squarely inside the definition even though the catchline says radar. The test is what the equipment is designed or intended to do, which is why a detector, designed only to hear a signal, sits outside it.

The section creates three separate offenses rather than one. Subsection (b) reaches knowingly possessing or selling a jamming device anywhere. Subsection (c) reaches knowingly operating a motor vehicle with a jamming device in the vehicle, so the device does not have to be switched on or even wired in; having it in the car while driving completes the offense. Subsection (d) reaches knowingly using one to interfere with police radar or lidar on a highway. Subsection (e) then makes any device used in violation of the section subject to seizure by any law enforcement officer, and it may be confiscated and destroyed by order of the court where the violation is charged, so the hardware is not coming back. Subsection (f) exempts law enforcement officers acting in their official capacity.

One carve-out saves ordinary radio equipment. Under (a)(3), a "radar jamming device" does not include equipment that is legal under FCC regulations, such as a citizens' band radio, a ham radio, or any other similar electronic equipment. A CB used to warn other drivers is therefore not a jammer in Tennessee, however it is being used.

The second statute is the one that surprises people, and it is aimed at the retailer, not the driver. Section 39-17-113(a) makes it an offense to offer to pay or to pay the motor vehicle traffic citation of any person who purchased a device to detect, or to interfere with or diminish the measurement capabilities of, police radar or laser. Subsection (b) limits the section to persons and firms that sell or lease such devices, so a friend who chips in on your fine commits nothing; the target is the ticket reimbursement guarantee that detector retailers advertise. Subsection (c) sets a Class B misdemeanor punishable by a fine only of up to five hundred dollars ($500), and provides that each day a violation occurs is a separate offense, which turns a standing advertised guarantee into a per-day exposure. It was added by Public Chapter 730 of 2006 and took effect July 1, 2006, the same day as the jamming statute enacted six weeks later as Public Chapter 853.

Because Tennessee runs no periodic vehicle inspection, nothing about a detector is ever checked administratively. The equipment only comes to notice at a roadside stop, and a detector on the windshield is not itself a reason for one.

00), or both. Actually using a jammer against police radar or lidar under (d) is a Class B misdemeanor, carrying up to six (6) months or a fine of up to five hundred dollars ($500) under § 40-35-111(e)(2). On top of the sentence, subsection (e) allows any law enforcement officer to seize the device, and the court hearing the charge may order it confiscated and destroyed. A retailer that offers to pay or pays a customer's traffic citation under § 39-17-113 faces a Class B misdemeanor punishable by a fine only, capped at five hundred dollars ($500), with each day of violation charged as a separate offense.

None of these penalties attaches to owning, mounting or operating a receive-only radar or laser detector in a private passenger vehicle, and § 39-16-610(f) removes law enforcement officers acting in their official capacity from the section entirely.