Radar detectors are legal in California, jammers are not

California has exactly one jamming statute. Division 12, Chapter 5, Article 17 of the Vehicle Code is titled "Jamming Devices" and consists of section 28150 alone, added by Stats. 1998, Ch. 493, Sec. 1, effective January 1, 1999. Subdivision (a) bars equipping a vehicle with any device designed for, or capable of, jamming, scrambling, neutralizing, disabling or otherwise interfering with radar, laser, or any other electronic device a law enforcement agency uses to measure the speed of moving objects. Subdivision (b) goes further than the vehicle and reaches the person: no one may use, buy, possess, manufacture, sell or otherwise distribute such a device. A passive detector does the opposite of what that language describes. It receives a signal already in the air and does not interfere with the police instrument, and no other Vehicle Code section reaches detectors at all.

The jamming ban is graduated. Under section 28150(c) a violation of subdivision (a) or (b) is an infraction, but section 28150(d) makes a person who possesses four or more devices in violation of subdivision (b) guilty of a misdemeanor, which is the threshold the Legislature chose to separate a driver from a distributor. Subdivision (e) carves out one lawful carrier: a person holding a valid federal license to operate the devices may transport one or more of them so long as the license is carried in the vehicle at all times while the device is being transported. Note that section 28150 says "radar, laser, or any other electronic device," so a laser jammer or shifter is covered even though a laser detector is not.

The question that actually gets Californians ticketed is mounting. Vehicle Code section 26708(a)(1) forbids driving with any object or material placed, displayed, installed, affixed or applied upon the windshield or side or rear windows, and section 26708(a)(2) forbids anything in or upon the vehicle that obstructs or reduces the driver clear view through the windshield or side windows. The exemption list in subdivision (b) is specific and closed: seven-inch squares in the lower corner of the windshield and rear window farthest from the driver and a five-inch square in the lower corner nearest the driver for signs and stickers under (b)(3); an electronic communication device in a five-inch square at the center uppermost portion of the windshield for California Highway Patrol communication or electronic toll and traffic management under (b)(11); a portable GPS under (b)(12); and a video event recorder under (b)(13). A radar detector is not on that list. Suction cupping one to the middle of the windshield or high near the mirror is therefore exposed under subdivision (a), while a detector sitting on the dash or clipped where it does not attach to the glass and does not cut into the clear view is outside the section entirely.

Commercial drivers get the opposite answer. Federal regulation 49 C.F.R. 392.71(a) prohibits using a radar detector in a commercial motor vehicle or operating a commercial motor vehicle that is equipped with or contains any radar detector, and paragraph (b) forbids a motor carrier from requiring or permitting a driver to do so. That rule has been in place since 58 FR 67375, December 21, 1993, and it applies to interstate commercial operation in California regardless of the state code being silent on detectors.

A jamming device violation under Vehicle Code section 28150(a) or (b) is an infraction, so Vehicle Code section 42001(a) caps the fine at $100 for a first offense, $200 for a second infraction within one year of a conviction, and $250 for a third or subsequent within a year of two or more convictions, before penalty assessments. Possession of four or more jamming devices is a misdemeanor under section 28150(d) and is charged rather than cited. A radar detector itself carries no penalty because there is no offense to charge; if a detector generates a citation it will be written under section 26708 for obstructing the windshield.

5(e) and section 40610(a)(1) require the officer to issue a notice to correct violation unless one of the section 40610(b) disqualifiers applies, and the correction period stated on the notice may not exceed 30 days. Proof that the detector was moved off the glass may be certified by a police department, the California Highway Patrol, a sheriff, a marshal or another agency regularly enforcing the Vehicle Code under section 40616(c), and the clerk collects a $25 transaction fee per violation under section 40611(a). Willfully failing to deliver proof of correction is a misdemeanor under section 40616.