Missouri Auxiliary Lights: Three Lamps, 12 to 42 Inches, White or Amber Only

Start with the definition, because Missouri's is narrow. Section 307.020(2) defines an auxiliary lamp as an additional lighting device on a motor vehicle used primarily to supplement the headlamps in providing general illumination ahead of a vehicle. A rock light, a bed light or a rear-facing chase light is not an auxiliary lamp under that definition and falls instead under Section 307.100. Section 307.020(4) supplies the measuring convention that makes the height rule workable: mounting height is the distance from the center of the lamp to the surface on which the vehicle stands, so a bumper bar is measured at its centerline, not at its lowest edge. The twelve to forty-two inch band in Section 307.080 rules out both the low-slung bumper pods common on lifted trucks and any bar mounted at the top of a windshield or on a roof rack.

Color is where Missouri is strictest. Section 307.095.1 requires headlamps to exhibit light substantially white in color, and auxiliary lamps, cowl lamps and spotlamps to be substantially white, yellow or amber. The same subsection then adds a flat prohibition: no person shall drive or move any vehicle or equipment, except a school bus used for school purposes or an emergency vehicle, with any lamp or device displaying a red light visible from directly in front. That single sentence is what makes forward-facing red halos, red grille lights and red underglow illegal in Missouri regardless of brightness. Section 307.085 handles the side lamps separately: no more than two side cowl or fender lamps, each white or yellow without glare, and no more than one running board courtesy lamp on each side, again white or yellow without glare. A backup lamp is allowed alone or in combination with another lamp, but it may not be continuously lighted while the vehicle is moving forward.

Spotlamps get their own section and their own, heavier penalty. Section 307.090 permits not more than one spotlamp per motor vehicle, and requires every lighted spotlamp to be so aimed and used as not to be dazzling or glaring to any person. Unlike the auxiliary lamp rule, that violation is a class C misdemeanor rather than an infraction.

Section 307.100 catches everything else. Any lighted lamp or illuminating device other than headlamps, spotlamps, front direction signals or auxiliary lamps that projects a beam greater than three hundred candlepower must be aimed so that no part of the beam strikes the roadway more than seventy-five feet from the vehicle. The same section prohibits alternately flashing warning signals on ordinary vehicles, allowing them only on school buses used for school purposes, on vehicles carrying United States mail from post offices to addressees' boxes, on emergency vehicles as defined in Section 304.022, on buses owned or operated by churches, mosques, synagogues, temples or other houses of worship, and on commercial passenger transport vehicles or railroad passenger cars stopped to load or unload. On every other motor vehicle, motorcycle and motor-drawn vehicle, flashing is permitted only as a means of indicating a right or left turn. Section 307.105 supplies the total-count rule: where a vehicle has its required headlamps plus any auxiliary lamps, a spotlamp, or any other front lamp over three hundred candlepower, no more than four such front lamps may be lighted at any one time on a highway.

Colored emergency lighting is governed by Section 307.175, a permit scheme rather than an equipment rule. Fixed, flashing or rotating red or red and blue lights are confined to emergency vehicles responding to an emergency, fire, ambulance and rescue vehicles on a call, Department of Transportation contractors stationary in a signed work zone between dusk and dawn with highway workers present and no more than two vehicles lit, and coroners, medical examiners and forensic investigators responding to a scene. Amber or amber and white is confined to state highways and transportation commission vehicles, department contractors, and utility workers stationary in a signed work zone.

Two Missouri quirks worth knowing. Section 307.122 bans any device that emits an electronic message directed to the front, side or rear of a vehicle's exterior, with message defined to include words, phrases, sentences, numbers and other symbols, sparing only the rear registration plate lamp under Section 307.075, a route indicator on a bus or public transportation vehicle, and displays of the proper name of a firm or corporation. That is what stops scrolling LED tailgate panels. And Section 307.005 gives LED equipment a tolerance found in few codes: a lamp made of multiple light-emitting diodes is deemed to be operating properly so long as not less than seventy-five percent of the diodes work, a rule the Highway Patrol repeats in its inspection definitions at 11 CSR 50-2.010(1)(J).

120, the violation is an infraction. 1(6) caps the fine at four hundred dollars. 4 provides that a court shall not issue a warrant for failure to appear for any violation classified or charged as an infraction under chapter 307. Two lighting offenses sit outside that regime. 1(8) and a fine up to seven hundred fifty dollars. 175 is a class A misdemeanor, up to one year and a fine up to two thousand dollars. 180(6), rejects a vehicle when a light or reflector is obstructed, when a lamp is not securely mounted, or when a light or reflector shows color contrary to law, though subsection (5) tells inspectors not to inspect side marker lights, parking lights, four-way flashers, backup lights, interior lights, license plate lights or clearance lights.