New Hampshire Has No Radar Detector Statute, Only the Truck Rule

New Hampshire never legislated on speed-measurement countermeasures. A full-text search of the Revised Statutes on the General Court's own search page returns no section containing radar, and none containing jammer. The same engine returns 25 sections for moose and 3 for speedometer, so the zero is a real absence and not a broken query. There is no registration offence, no possession offence and no confiscation power aimed at detectors anywhere in Title XXI, the motor vehicle title.

The restriction that does exist arrives by incorporation. RSA 266:72-a, I lets the commissioner of safety adopt as rules the current version of the federal motor carrier safety regulations contained in 49 C.F.R. parts 107, 380 and 382 through 397, and provides that any later amendment by the federal agencies amends the state rules automatically without further action by the commissioner. Saf-C 901.02(a) exercises that power and incorporates 49 CFR 107, 382, and 385 through 397. Radar detectors sit at 49 C.F.R. 392.71, inside that block: paragraph (a) says no driver shall use a radar detector in a commercial motor vehicle, or operate a commercial motor vehicle equipped with or containing any radar detector, and paragraph (b) says no motor carrier shall require or permit a driver to violate paragraph (a).

Two features of the New Hampshire adoption matter. First, Saf-C 901.01 states that the rules apply to all motor carriers and all drivers of commercial motor vehicles in either intrastate or interstate commerce, so a New Hampshire truck that never crosses the state line is still covered. Second, Saf-C 902.02 narrows the term: commercial motor vehicle means the vehicle defined in 49 CFR 390.5 except for vehicles designed or used to transport less than 16 passengers including the driver, and except for vehicles described in RSA 266:72-a, VI. The current version of these rules took effect on 7-17-23 by rule #13684.

The RSA 266:72-a, VI exclusion is worth reading before assuming a working truck is caught. It exempts a vehicle operating intrastate on New Hampshire farm or agricultural plates, with a gross vehicle weight, gross vehicle weight rating or gross combination weight rating of 26,000 pounds or less, designed or used to carry fewer than 16 passengers including the driver, and not carrying materials that must be placarded under 49 C.F.R. part 172 subpart F, from parts 391, 392, 393, 395 and 396 as adopted. The exemption is expressly clawed back only for 49 C.F.R. 392.3 on driving while fatigued or ill, 392.4 on illegal drugs, 392.5 on alcohol, part 393 subpart C on brakes, and 396.7 on unsafe operations. Section 392.71 is not among the clawbacks, so the radar detector rule does not reach that class of farm plated vehicle.

Enforcement of the motor carrier rules is roadside. RSA 266:72-a, V(a) requires a driver of a motor carrier to stop on the request of a Department of Safety enforcement officer, or another law enforcement agent certified to conduct truck inspections, or by command of roadside signs, so that the officer may examine vehicle components, the driver's physical condition, cargo condition and documents, and may enter the cab or cargo area. Under V(c) an operator who fails to stop or allow inspection is guilty of a misdemeanor, and a second violation results in suspension of the person's licence or privilege to drive in New Hampshire together with notification to national motor vehicle licence databases.

Mounting is the one thing a passenger-car driver still has to think about. RSA 265:95, III bars driving with any sign, poster, sticker or other nontransparent material upon or adjacent to the front windshield, side wings, or side or rear windows that obstructs the driver's clear view of the way or any intersecting way, unless authorized by the director. RSA 265:95, IV sets a $75 fine. A suction-cup detector high on the windshield or clipped to a visor raises that question, not a detector question.

There is no New Hampshire penalty for owning or using a radar detector in a passenger vehicle, because no statute addresses them. R. 02(a), and the carrier that requires or permits it breaches paragraph (b). Those breaches are handled through the motor carrier enforcement machinery in RSA 266:72-a rather than as a Title XXI equipment violation. Refusing the roadside inspection that would find the detector is itself a misdemeanor under RSA 266:72-a, V(c), with a second refusal costing the driver's licence or privilege to drive and a report to national licence databases.

Separately, mounting any device so that it obstructs the driver's clear view through the windshield or side windows is a breach of RSA 265:95, III carrying a $75 fine under paragraph IV, and it applies to every driver regardless of what the device does.