Radar detectors are not illegal in California for anyone driving a private passenger vehicle. You can buy one, own one, and use one on the road. The catch is where you put it: state law bans attaching objects to the windshield, so the device has to sit on the dashboard, clip to the visor, or hardwire below the dash. Jammers are a separate product and are illegal for everyone, and commercial drivers can’t use a detector at all under federal law.
Where You Can Mount It
California Vehicle Code 26708 makes it illegal to place any object on the windshield, side windows, or rear window that blocks or reduces your view of the road. The statute lists specific exceptions for GPS units, toll transponders, and event recorders, each allowed in designated small areas of the glass. Radar detectors are not on that list.
So suction-cupping a detector to the windshield is a citable offense, even though the detector itself is legal to own and use. Put it on the dash, clip it to the visor, or hardwire it below the dash line. As long as it doesn’t obstruct your sightline, you’re in compliance.
The 2026 Uniform Bail and Penalty Schedule sets the base fine for a standard vehicle-equipment infraction at $35, but once California’s penalty assessments, surcharges, and court fees are added, the total comes to roughly $233.1California Courts. Uniform Bail and Penalty Schedules 2026 Officers sometimes write it as a correctable violation, which lets you get the ticket dismissed by showing you moved the device. That’s discretionary, not guaranteed.
Jammers Are Illegal
A detector and a jammer are not the same product, and California treats them very differently. A detector passively listens for police speed-measurement signals and alerts you. A jammer actively blocks or scrambles those signals so the officer can’t get a reading.
Vehicle Code 28150 bans any device designed to interfere with radar, laser, or other speed-measurement equipment used by law enforcement. You cannot equip your car with one, and you cannot buy, possess, sell, or distribute one. A first offense is an infraction. Being caught with four or more jamming devices bumps the charge up to a misdemeanor, which can carry jail time on top of fines.2California Legislative Information. California Vehicle Code 28150 – Jamming Devices The only exception is for someone holding a valid federal license to operate such equipment, with the license in the vehicle at all times.
Federal law reinforces the ban. The FCC treats any device that jams authorized radio communications as illegal to operate, market, or sell, with penalties that include fines, criminal prosecution, and seizure of the equipment.3Federal Communications Commission. Jammer Enforcement Buying a laser jammer online and never turning it on still violates state law because possession alone is enough.
Commercial Drivers Cannot Use One
Driving a commercial motor vehicle changes the answer entirely. Title 49 CFR 392.71 prohibits any driver from using a radar detector in a CMV, and prohibits a CMV from being equipped with or even containing one.4eCFR. 49 CFR 392.71 – Radar Detectors; Use and/or Possession An unplugged detector in the glove box still counts. Motor carriers are also barred from requiring or allowing drivers to have one.
The FMCSA definition of a commercial motor vehicle covers any vehicle with a gross vehicle weight rating of 10,001 pounds or more, vehicles designed to carry more than eight paying passengers or more than 15 passengers total, and vehicles hauling placarded hazardous materials.5eCFR. 49 CFR 390.5 – Definitions That sweeps in most semi-trucks, box trucks, large delivery vehicles, and buses.
Officers check for detectors during roadside inspections. A violation can result in fines and negative marks on the driver’s safety record, and many carriers treat possession as grounds for discipline because a single FMCSA violation also reflects on the company’s safety rating.
If You Drive Out of State
Detectors are legal for private vehicles in 49 states, but a few places will get you a ticket.
Virginia bans all radar detectors for every driver. Under Virginia Code 46.2-1079, it’s illegal to drive any vehicle equipped with a device that detects or interferes with police speed-measurement equipment. A powered, accessible detector in the car is enough. The officer doesn’t need to prove it was on or working. The penalty is a fine with no demerit points on your driving record. If you’re passing through, unplug the detector, remove any power source, and stow it somewhere out of reach like the trunk. A device with no power and no ready access isn’t a violation.6Virginia Code Commission. Virginia Code 46.2-1079 – Radar Detectors; Demerit Points Not to Be Awarded
Washington, D.C. also prohibits radar detectors in passenger vehicles under its municipal traffic regulations, with potential fines and device seizure.
Federal law prohibits radar detectors on military bases nationwide. If you drive onto a base, turn the device off and stow it before you reach the gate.