Arizona Radar Detector Rules and Mounting Limits

Arizona's answer comes from the structure of Title 28, chapter 3, article 16, which is the entire body of state law on what a vehicle may and may not carry. That article is a closed list. It requires head lamps, tail lamps, stop lamps, brakes, mirrors, a windshield, wipers, safety glass, mufflers and splash guards. It restricts window film, lamp colors, flashing lamps, image display devices, tire equipment and exhaust systems. Section 28-921(A) makes the list binding on the driver and on the owner alike: no one may drive, and an owner may not knowingly cause or permit to be driven, a vehicle that lacks required equipment in proper condition and adjustment or that is equipped in any manner in violation of the article. Section 28-921(B) then does the opposite job, and it is the sentence that answers this question: the article does not prohibit the use of additional parts and accessories if the use is not inconsistent with the article.

Nothing in that article, and nothing elsewhere in Title 28 or in the criminal code at Title 13, reaches a radar detector. There is no section on detection devices, none on jamming or interfering with a speed measuring device, and none on possession of countermeasure equipment. The nearest thing Title 13 contains is section 13-2922, which punishes interference with transmissions on public safety land mobile radio frequencies, a two-way radio offense that has nothing to do with a receiver that listens for K band or Ka band. So the accessory is permitted by section 28-921(B) and is not made inconsistent with the article by anything the article says.

No Arizona city or county can change that. Section 28-626(A) declares the provisions of chapter 3 applicable and uniform throughout the state and in all political subdivisions, and section 28-626(B)(1) forbids a local authority from enacting or enforcing an ordinance in conflict with the chapter unless the chapter expressly authorizes it. Section 28-627(A) then lists what a local authority may regulate on its own streets, and the list runs to parking, one-way designations, through highways, park speed limits, processions, bicycle registration, turning restrictions, prima facie speed limit alterations, off-highway vehicle access routes and electric bicycles. Vehicle equipment is not on it. A municipal detector ban would be an ordinance in conflict with chapter 3 and void under section 28-626(B)(1).

The mounting is the part that actually generates Arizona citations. Section 28-959.01(B) prohibits operating a motor vehicle with an object or material placed, displayed, installed, affixed or applied on the windshield or side or rear windows, or placed in or on the vehicle, in a manner that obstructs or reduces a driver's clear view. The section names twelve exceptions and a windshield-mounted detector has to land in one of them. Paragraph A.5 covers only signs, stickers and other materials in a seven inch square in the lower corner of the windshield farthest from the driver and a five inch square in the lower corner nearest the driver. Paragraph A.12 covers safety monitoring equipment and driver feedback mounted immediately behind, slightly above or slightly below the rearview mirror, or where the rearview mirror would commonly sit. Paragraph A.4 protects an adjustable nontransparent sun visor mounted forward of the side windows and not attached to the glass, which is why a visor clip is the cleanest mounting choice in Arizona. A suction cup planted in the middle of the glass at eye level fits none of them. Section 28-893 covers the same ground for cargo and passengers, barring driving when the load or passengers obstruct the view to the front or sides.

Commercial drivers are in a different position entirely. 49 C.F.R. section 392.71(a) states that 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, and subsection (b) forbids a motor carrier from requiring or permitting a driver to do so. Possession in the cab is enough. Arizona brings that rule home through Title 28, chapter 14: section 28-5202(C) states the chapter applies throughout the state for the purpose of enforcing state and federal laws and rules relating to the operation of commercial motor vehicles, and section 28-5204(C) makes the Department of Public Safety the mandatory enforcer, with political subdivisions able to enforce through officers DPS has certified. Section 28-5201(1) sets who counts: a vehicle or combination at 26,001 pounds or more used in intrastate commerce, at 10,001 pounds or more in interstate commerce, a school bus, a bus, a vehicle carrying passengers for hire with a design capacity of nine or more, or a placarded hazardous materials vehicle.

One practical point about what a detector can and cannot do in Arizona. Section 28-1206 provides that the state and local authorities may not use a photo enforcement system on a state highway to identify violators of article 3 or article 6 of chapter 3, which are the traffic signal and speed restriction articles, so fixed cameras on the state highway system are off the table. Municipal streets are another matter, and there a detector is beside the point because the citation arrives in the mail. Section 28-1204 gives drivers a different safeguard: an agency using photo enforcement must adopt signage standards providing at least two signs before the system, one roughly three hundred feet ahead, with a posted speed limit sign between them, and must remove or cover those signs when the system is not operating. Under subsection D the court may dismiss a citation issued while those standards were not in effect, and under subsection E the rear of a photo enforcement vehicle must be clearly marked while it is being used. Subsection F excuses the signage requirement for a mobile photo enforcement vehicle deployed on streets posted at forty miles per hour or less.

Owning, carrying and using a radar detector in a private vehicle is not an offense in Arizona, so there is no fine, no civil penalty and no point assessment for the device itself. What can be cited is the installation. A windshield mount that obstructs the driver's clear view breaches A.R.S. section 28-959.01(B), which sits in Title 28, chapter 3, making it a civil traffic violation under section 28-121(B) with a civil penalty capped at two hundred fifty dollars by section 28-1598, plus the surcharges the court must levy under sections 12-116.01 and 12-116.02. Section 28-982 gives the practical outcome: an officer with reasonable cause may require the vehicle to be stopped and inspected, and issues a written notice specifying the defect and requiring a certificate of correction or adjustment within five days. Relocating the detector to the visor or to the mirror zone answers that notice.

Commercial drivers face a materially harsher regime. A radar detector found in the cab is a violation of 49 C.F.R. section 392.71 and therefore of Title 28, chapter 14, enforced by the Department of Public Safety under section 28-5204(C). Section 28-5240 makes a violation of that chapter or of a rule adopted under it a civil traffic violation, and section 28-5241 backs the scheme with out-of-service orders whose breach carries its own classification and civil penalty. Section 28-5232 lets the state suspend a registration or license where continued operation is a danger to public safety, and section 28-5237 provides the hearing route where noncompliance is alleged.