California Lane Splitting Is Lawful Under Vehicle Code 21658.1

Vehicle Code section 21658.1(a) supplies the statutory definition: lane splitting is "driving a motorcycle, as defined in Section 400, that has two wheels in contact with the ground, between rows of stopped or moving vehicles in the same lane, including on both divided and undivided streets, roads, or highways." Three parts of that sentence do real work. It reaches only a two-wheeled motorcycle, so a trike or a three-wheeled autocycle is outside the definition. It covers stopped and moving traffic, so the California rule is not confined to filtering forward at a stop. And it applies on undivided streets as well as divided highways, so the practice is not limited to freeways.

What makes lane splitting legal in California is an absence rather than a grant. Section 21658.1 never says a motorcyclist may split lanes. The Legislature instead defined the term and left the Vehicle Code without any prohibition on it. The lane discipline rule at section 21658(a) says a vehicle "shall be driven as nearly as practical entirely within a single lane and shall not be moved from the lane until such movement can be made with reasonable safety," and the Legislature did not amend that section when it added 21658.1 through Stats. 2016, Ch. 141 (AB 51), effective January 1, 2017. Section 21658.1 sits in Division 11, Chapter 3, Article 1 of the Vehicle Code, among the driving-on-the-right rules.

Subdivision (b) says the California Highway Patrol "may develop educational guidelines relating to lane splitting in a manner that would ensure the safety of the motorcyclist and the drivers and passengers of the surrounding vehicles." The verb is permissive and the product is educational. Nothing in section 21658.1 makes a departure from CHP guidance a violation, and the section carries no penalty clause of its own. Subdivision (c) directs the department, when it does develop guidelines, to consult the Department of Motor Vehicles, the Department of Transportation, the Office of Traffic Safety, and a motorcycle organization focused on motorcyclist safety.

No California city or county can undo any of this. Vehicle Code section 21 provides that, except as expressly provided, the code is "applicable and uniform throughout the state and in all counties and municipalities therein, and a local authority shall not enact or enforce any ordinance or resolution on the matters covered by this code, including ordinances or resolutions that establish regulations or procedures for, or assess a fine, penalty, assessment, or fee for a violation of, matters covered by this code, unless expressly authorized by this code." Lane use and motorcycle operation are matters covered by the code, so a municipal lane-splitting ban would be unenforceable. The rule a rider follows in Los Angeles is the rule in Redding.

The maneuver is legal; the manner of doing it is still policed. Section 22350, the basic speed law, forbids driving "at a speed greater than is reasonable or prudent having due regard for weather, visibility, the traffic on, and the surface and width of, the highway," which is the section most often reached for when a rider splits far faster than the traffic being passed. Section 22107 bars moving right or left on a roadway until the movement can be made with reasonable safety and then only after an appropriate signal. Section 21658(b) requires drivers to obey official signs allocating lanes to traffic moving in the same direction. None of these mention lane splitting, and all of them apply to it.

1 creates no offense, so there is no citation for lane splitting itself in California. Enforcement runs through the general rules of the road instead: a speed unsafe for the gap being used is cited under section 22350, and a lateral move made without reasonable safety or without a signal under section 22107. 1 makes it "unlawful and constitutes an infraction for any person to violate, or fail to comply with any provision of this code, or any local ordinance adopted pursuant to this code" unless the code says otherwise, so these are infractions rather than misdemeanors.

Section 42001(a) sets the base fine at not more than $100 for a first infraction, not more than $200 for a second occurring within one year of a prior infraction that resulted in a conviction, and not more than $250 for a third or subsequent infraction within one year of two or more prior convictions, before the statutory penalty assessments a court adds on top. Enforcement is by the California Highway Patrol on state highways and by city police and county sheriffs elsewhere.