Missouri Lane Splitting: No Authorizing Statute, Cited Under Lane Discipline

Missouri belongs to the group of states that legislated neither way. That silence is a choice rather than an oversight, and the structure of the code shows it. When the General Assembly wants to write a rule for motorcyclists it does so plainly: Section 304.285, enacted in 2009, gives the operator of a motorcycle or bicycle an affirmative defense to a red light charge under Section 304.281 or Section 304.301 where the rider has come to a complete stop, the signal continues to show red for an unreasonable time, the signal is apparently malfunctioning or has failed to detect the motorcycle, and no vehicle or person is approaching so as to constitute an immediate hazard. Section 302.020.2 sets a helmet requirement that applies only to riders and passengers under twenty-six years of age, bars any political subdivision from imposing its own helmet requirement, and provides that no person shall be stopped, inspected or detained solely to determine compliance with it. Missouri legislates for motorcycles when it means to, and it has never legislated for lane splitting.

The operative rules are the ordinary lane rules in Section 304.015, and which subsection applies depends on how many lanes the road carries. Subsection 5 opens with the condition that the roadway "has been divided into three or more clearly marked lanes for traffic", and subdivision (1) then requires that a vehicle be driven as nearly as practicable entirely within a single lane and not moved from that lane until the driver has first ascertained that the movement can be made with safety. Where the rider is on a road with only two lanes running in his direction, subsection 6 is the rule instead: all vehicles in motion on a highway having two or more lanes proceeding in the same direction shall be driven in the right-hand lane except when overtaking and passing, when preparing to make a proper left turn, or when otherwise directed by traffic markings, signs or signals. Neither text leaves room for straddling a lane line, and neither carves out a two-wheeled vehicle.

Filtering forward past stopped traffic runs into Section 304.016.2. A driver may overtake and pass to the right only when the overtaken vehicle is making or about to make a left turn, upon a city street with unobstructed pavement of sufficient width for two or more lines of vehicles in each direction, upon a one-way street, or upon a highway outside a city with unobstructed pavement of sufficient width and clearly marked for four or more lines of traffic. Those movements are permitted only when they can be made in safety, and the statute adds that in no event shall the movement be made by driving off the paved or main traveled portion of the roadway. A rider running up the shoulder of Interstate 70 or Interstate 44 past a backup is therefore in breach of an express prohibition, not merely of a general standard. The contrast with bicycles is instructive: Section 307.191.1 expressly authorizes a bicycle moving slower than the flow of traffic to operate on the shoulder adjacent to the roadway, and Section 307.190 expressly allows bicyclists to ride abreast when not impeding other vehicles. Missouri gave those permissions to bicycles and to motorized bicycles, and to nothing else.

A Missouri city cannot fix this locally. Section 304.120.2(1) lets municipalities make additional rules of the road and traffic regulations to meet their needs and traffic conditions, but Section 304.120.3 provides that no ordinance shall be valid which contains provisions contrary to or in conflict with chapter 304. A city ordinance purporting to authorize riding between lanes would conflict with Section 304.015, so the power runs one way only: a Missouri municipality may add restrictions, not permissions. Riders should also keep Section 304.012 in view. As amended by H.B. 495 effective August 28, 2025, it requires every person operating a motor vehicle on Missouri roads to drive in a careful and prudent manner and to exercise the highest degree of care, and makes a violation a class B misdemeanor, or a class A misdemeanor where an accident is involved. That is the charge most likely to be added to a lane-splitting stop that ends badly.

015 is a class C misdemeanor under subsection 9, which becomes a class B misdemeanor if the violation causes an immediate threat of an accident and a class A misdemeanor if an accident results from it. 5 likewise makes an improper pass a class C misdemeanor. 1(4) caps the fine at $750; the class B tier runs to six months and $1,000 and the class A tier to one year and $2,000. 1(1) puts two points on a Missouri license for any moving violation of a state law or of a county, municipal or federal traffic ordinance that is not separately listed, other than a violation of vehicle equipment provisions.

Lane discipline and improper passing are moving violations, so a lane-splitting citation is a two-point conviction rather than a no-point equipment ticket. Enforcement is by the Missouri State Highway Patrol on the state system and by municipal and county officers elsewhere; there is no administrative appeal, and a rider who wants to contest the citation does so in the associate circuit or municipal division where it was issued.