Are Radar Detectors Legal in California? Mounting Rules, Jammers and Trucks

Last reviewed: October 18, 2026. This article is general information, not legal advice. California statutes change, so check the current Vehicle Code or ask a California attorney if you get a citation.

California has more drivers than any other state, and a radar detector is a common sight on dashboards from the 405 to I-5 through the Central Valley. The device itself is legal. The catch in California is mounting: the state has one of the strictest windshield laws in the country, and it doesn't make an exception for radar detectors. This page covers California; for other states, see our guide to where radar detectors are legal.

Short answer: yes, radar detectors are legal in California in private passenger vehicles. But Vehicle Code § 26708 bans objects on the windshield outside a few listed spots, so mount yours on the dash or rearview mirror rather than the glass. Radar and laser jammers are illegal to use, buy or even possess under Vehicle Code § 28150. Detectors are banned in commercial motor vehicles.

Private cars: the detector is legal

California has no statute that bans owning or using a radar detector in a private car, SUV, minivan or pickup. That applies to residents and to visitors driving through.

A detector is a receiver. It listens for police radar (and, on many models, laser) and warns you. That's why § 28150 doesn't reach it: the jammer statute is aimed at devices designed for "jamming, scrambling, neutralizing, disabling, or otherwise interfering" with police equipment, and a passive detector does none of those things.

A detector doesn't change the speed limit, and California officers can still pace you or use other methods. It's a warning, not a defense.

Why mounting matters most in California

Most states only ban windshield objects that materially block your view. California's § 26708(a)(1) is different: it bans any object or material on the windshield, side or rear windows, and then lists exceptions in subdivision (b). Radar detectors aren't on that list.

Here are the exceptions that come closest:

• Signs, stickers or other materials (b)(3): allowed in "a seven-inch square in the lower corner of the windshield farthest removed from the driver", the same size in the lower corner of the rear window farthest from the driver, or "a five-inch square in the lower corner of the windshield nearest the driver."
• Portable GPS (b)(12): may be mounted in the same 7-inch or 5-inch squares, "outside of an airbag deployment zone," if used only for door-to-door navigation.
• Video event recorders (b)(13): the same lower-corner squares, or a 5-inch square at the center top of the windshield.
• Toll and CHP communication devices (b)(11): a 5-inch square at the center top of the windshield.
• Rearview mirrors (b)(1): exempt.

Whether a radar detector counts as "other materials" under (b)(3) isn't spelled out, and the GPS and recorder exceptions are tied to specific devices. So a suction-cup mount in the middle of the glass, the way many detectors are sold, is the setup most likely to get you a ticket.

Subsection (a)(2) adds a second layer: even an object that's not on the glass, such as a dash-mounted unit, can't obstruct or reduce your clear view through the windshield or side windows.

Safer ways to mount a detector in California

• Rearview-mirror mount. Clips onto the mirror stem rather than the glass.
• Dash mount with a non-slip pad, kept low enough that it doesn't block your view.
• Remote or hard-wired install, with only a small display inside the cabin.
• If you must use the glass, keep it within the lower-corner squares and away from the airbag zone, knowing the law doesn't clearly authorize it.
• Tidy the cord so it doesn't hang across the windshield.

The penalty

Section 26708 doesn't set its own penalty. Under Vehicle Code § 40000.1, a violation of the Vehicle Code is an infraction unless another rule says otherwise. The amount you pay depends on the bail schedule and the court's added penalties, so we won't quote a single figure.

The same section also governs window film. See our guide to window tint laws in California.

Radar and laser jammers: banned under § 28150

California's jammer law is one of the broadest in the country. Here's how § 28150 works:

• Equipment ban (a): "No vehicle shall be equipped with any device that is designed for, or is capable of, jamming, scrambling, neutralizing, disabling, or otherwise interfering with radar, laser, or any other electronic device used by a law enforcement agency to measure the speed of moving objects." Note "or is capable of": a combo unit that can jam is covered even if you don't switch that feature on.
• Possession ban (b): using, buying, possessing, making, selling or distributing one is banned. There's no storage exception for a unit in the trunk.
• Penalties (c) and (d): a violation is an infraction, but possessing four or more devices in violation of subdivision (b) is a misdemeanor.
• Federal license exception (e): a person with a valid federal license for operating these devices may transport them if the license is carried in the vehicle at all times.

Radar jammers are also illegal under federal law, which says no person shall "willfully or maliciously interfere with or cause interference to any radio communications of any station licensed or authorized by or under this chapter or operated by the United States Government" (47 U.S.C. § 333).

Commercial trucks and buses: not allowed

The federal rule in 49 CFR 392.71 bans radar detectors in commercial motor vehicles: "No driver shall use a radar detector in a commercial motor vehicle, or operate a commercial motor vehicle that is equipped with or contains any radar detector." Under § 392.71(b), a motor carrier may not "require or permit" a driver to break the rule.

Under 49 CFR 390.5, a CMV generally includes a vehicle with a weight rating of 10,001 pounds or more used in interstate commerce, one designed or used to carry more than 8 passengers (including the driver) for pay or more than 15 not for pay, or one carrying placarded hazardous materials. The same section defines "radar detector" to include devices that detect police laser and "any other future speed measurement technology."

California's Highway Patrol enforces its own motor carrier safety regulations for carriers that stay inside the state, in Title 13 of the California Code of Regulations. We could not open the official text to confirm exactly which federal rules it adopts, so if you drive a truck or bus only within California, ask your carrier's safety department or the CHP. In practice, leave the detector in your personal car.

The FCC rule behind modern detectors

The FCC regulates radar detectors as "unintentional radiators" under Part 15. Since 2002, 47 CFR § 15.109(h) has required that "Radar detectors shall comply with the emission limits in paragraph (a) of this section over the frequency range of 11.7-12.2 GHz." The FCC adopted the rule after finding that some detectors leaked strong signals into the band used by small satellite (VSAT) terminals. Buying an FCC-certified detector keeps you within federal equipment rules, but it doesn't change California's mounting or jammer laws.

Military bases and Washington, D.C.

• Military bases. Installations set their own traffic rules. Federal rules for Army installations (32 CFR § 634.25) note that Defense Department policy delegates authority to installation commanders to set additional traffic rules, and radar detectors are widely reported to be banned on bases. We could not open a single federal rule that bans them on every base. California has many large installations, so check the base's traffic code before driving on with a detector.
• Washington, D.C. The District bans selling detectors and using or possessing one in a car (18 DCMR § 736).

California compared with other states

For more detail, see our guides for Florida, Illinois and Virginia. If you ride as well as drive, our guide to lane splitting in California covers another rule where California differs from most states.

Practical do's and don'ts in California

• Do use a dash, mirror or remote mount instead of a suction cup in the middle of the windshield.
• Do check whether a "combo" unit can transmit. If it's capable of jamming, § 28150(a) applies.
• Do keep detectors out of trucks and buses you drive for work.
• Don't keep a jammer in the trunk; possession alone is an infraction.
• Don't let the cord or the unit block your view, even on the dash.
• Don't treat the detector as permission to speed.

Sources

• California Vehicle Code § 26708 (material obstructing or reducing driver's view): California Legislature
• California Vehicle Code § 28150 (jamming devices): California Legislature
• California Vehicle Code § 40000.1 (infractions): California Legislature
• 49 CFR § 392.71 (radar detectors in commercial motor vehicles): Cornell LII
• 49 CFR § 390.5 (definitions of commercial motor vehicle and radar detector): Cornell LII
• 47 U.S.C. § 333 (willful or malicious interference): Cornell LII
• 47 CFR § 15.109 (radiated emission limits, including radar detectors): eCFR
• FCC, Radar Detectors final rule, 67 FR 48993 (July 29, 2002): GovInfo
• 32 CFR § 634.25 (installation traffic codes): Cornell LII
• Virginia Code § 46.2-1079: Virginia Law
• District of Columbia Municipal Regulations, 18 DCMR § 736 (Radar Detectors and Jammers): DC Regulations