Six states allow motorcyclists to ride between cars, and the lane splitting and filtering laws vary sharply by state. California is the only state that permits full lane splitting through both moving and stopped traffic. Utah, Montana, Arizona, Colorado, and Minnesota allow the narrower practice of lane filtering, which is limited to traffic that is stopped or barely moving and capped at low speeds. In the other 44 states, riding between cars is treated as an illegal lane change, and a citation is the least of the problems a rider faces if a crash follows.
Splitting, Filtering, and Sharing Are Not the Same Thing
The legal rules turn on which maneuver you are actually doing.
Lane splitting means riding between rows of vehicles that may be moving or stopped, typically on a highway or multi-lane road. Only California permits this in its full form.
Lane filtering is more limited: riding between vehicles that are completely stopped (or in Montana, barely crawling) to reach the front of the line before traffic starts moving again. The five states besides California that allow riding between cars all restrict it to this low-speed version.
Lane sharing is two motorcycles riding side by side within the same lane. Most states permit this even where splitting and filtering are prohibited.
The Six States Where It Is Legal
Five of these laws have passed since 2019. All five chose the restrictive filtering model rather than California’s open-ended approach.
California: Full Lane Splitting, No Speed Cap
California Vehicle Code Section 21658.1 defines lane splitting as riding a two-wheeled motorcycle between rows of stopped or moving vehicles in the same lane, on any divided or undivided road.1California Legislative Information. California Vehicle Code 21658.1 The statute sets no speed limit for the maneuver. It directs the California Highway Patrol to publish safety guidelines instead.
The CHP’s current guidance warns that the risk of death or serious injury rises as overall speed and the speed gap between the motorcycle and surrounding traffic rise, but it sets no specific numerical cap.2California Highway Patrol. California Motorcyclist Safety A widely cited “10 mph” speed-differential figure appeared in an earlier CHP document that was later withdrawn and is not in the current guidelines.
Utah: Filtering at 15 MPH on Roads Posted 45 MPH or Below
Utah allows filtering only when the road has at least two lanes in the same direction and a posted limit of 45 mph or less. Every vehicle being overtaken must be completely stopped. The motorcycle cannot exceed 15 mph. The movement must be one the rider can make safely, and filtering is not permitted on on-ramps.3Utah Legislature. Utah Code 41-6a-704
Montana: Filtering at Up to 20 MPH
Montana gives riders slightly more room. Filtering is allowed when traffic is stopped or moving at 10 mph or less, the motorcycle cannot exceed 20 mph, and the lanes must be wide enough for the maneuver to be completed safely.4Montana State Legislature. Montana Code 61-8-392 – Lane Filtering for Motorcycles Unlike the other filtering states, Montana lets riders pass slow-moving vehicles, not just stopped ones.
Arizona: Filtering at 15 MPH on Roads Posted 45 MPH or Below
Arizona’s rules closely mirror Utah’s. A two-wheeled motorcycle may pass stopped vehicles and travel between lanes on roads with a speed limit of 45 mph or less, where there are at least two lanes in the same direction, and the motorcycle’s speed stays at or below 15 mph.5Arizona Legislature. Arizona Code 28-903 – Operation of Motorcycle on Laned Roadway Surrounding vehicles must be fully stopped.
Colorado: Filtering Through Stopped Traffic Only
Colorado’s filtering law took effect in August 2024. Riders may pass stopped vehicles when the lanes are wide enough for safe passage and the motorcycle stays at or below 15 mph. Once stopped vehicles begin moving, filtering must stop. Passing on the right shoulder, to the right of the farthest right-hand lane, or into oncoming traffic is prohibited.6Colorado Department of Transportation. New Lane Filtering Law Protects Motorcyclists
Minnesota: Filtering as of July 1, 2025
Minnesota became the newest filtering state on July 1, 2025. The law applies on roads with at least two lanes in the same direction, caps the motorcycle at 15 mph, and requires the rider to stop filtering once surrounding traffic begins moving. Filtering on the freeway shoulder or across a center divider is not allowed.7Minnesota Department of Public Safety. Minnesota Motorcycle Safety Center
The Other 44 States
Everywhere else, riding between cars in any form is treated as an illegal lane change or improper lane use. Officers typically cite riders under general statutes requiring vehicles to stay within a single marked lane. Base fines generally run from $100 to several hundred dollars, with court fees and surcharges pushing the total higher. If the officer views the riding as aggressive enough to qualify as reckless driving, the penalties move into a different tier entirely, and the consequences at a renewal of your insurance follow.
The direction of travel favors legalization, with six states in seven years. But until a bill passes in your state, filtering through a red light is a traffic violation, and the real cost shows up if you are in a crash.
Why the Speed Caps Sit at 15 MPH
The 15 mph cap written into most state filtering laws is not arbitrary. It comes from a UC Berkeley Safe Transportation Research and Education Center study of thousands of California motorcycle collisions, published by the California Office of Traffic Safety. Splitting riders were injured less often overall than non-splitting riders. Head injuries ran at 9% among splitters versus 17% among non-splitters, and fatal injuries at 1.2% versus 3.0%.8California Office of Traffic Safety. Motorcycle Lane-Splitting and Safety in California
Those lower injury rates only held when riders kept the speed gap modest. Up to a 15 mph differential, injury rates showed no meaningful increase. Riders going 15 to 25 mph faster than surrounding traffic were roughly twice as likely to suffer a head injury. Above a 25 mph differential, the rate was nearly triple. Overall traffic speed mattered too: once surrounding traffic exceeded 50 mph, injury rates climbed regardless of the differential.8California Office of Traffic Safety. Motorcycle Lane-Splitting and Safety in California This is the research behind the speed caps every filtering state has adopted.
What Happens After a Crash
The fault analysis after a lane splitting collision depends almost entirely on whether the maneuver was legal where it happened.
Where It Is Illegal
A rider who crashes while splitting in a state that prohibits it runs into a doctrine called negligence per se. Violating a safety statute that was meant to prevent the exact harm that occurred counts as the breach of duty automatically; the court moves directly to whether the violation caused the crash.9Legal Information Institute. Negligence Per Se
That does not mean 100% of the fault lands on the rider. Most states apply comparative negligence, which splits fault by percentage. A driver who changed lanes without signaling still contributed. But the rider’s illegal maneuver gives the defense a head start, and in states with a 50% or 51% bar, getting pushed past the line means the rider recovers nothing. Insurance adjusters know how to frame these cases to get there.
Where It Is Legal
When the maneuver was legal, both the rider and the driver are measured on how carefully each behaved. The motorcycle’s speed relative to traffic, lane position, whether the driver signaled, and whether either party was distracted all matter. A driver who moved over without checking mirrors can absorb most of the fault even though the motorcycle was between lanes, because the duty to look before merging still applied.
Camera footage is the single most useful thing a rider can carry. Front and rear cameras capture speed, lane position, and following distance in the seconds before impact. GPS data in the footage can confirm whether the motorcycle stayed under the state’s speed cap, which matters because exceeding it flips the legal analysis back toward negligence per se. Without footage, these cases often come down to a credibility contest the rider tends to lose.
Insurance Fallout
Even where filtering is legal, adjusters often use it as leverage to reduce payouts. The fact that the motorcycle was between lanes gives them a foothold to argue the rider created the hazard.
Where it is illegal, insurers cite the traffic violation directly. Any percentage of fault assigned to the rider cuts the recovery proportionally under comparative negligence, and that cut applies to every category of damages: ER bills, ongoing treatment, lost wages, and pain and suffering. A rider found 40% at fault loses 40% of the recovery, which on a serious injury claim is often tens of thousands of dollars. Expect premiums to rise at renewal after any lane splitting crash, regardless of who was found at fault.
What Drivers Owe Riders in Filtering States
Legalization created obligations for drivers too. In filtering states, drivers are expected to know that motorcycles may pass between lanes in slow or stopped traffic. Minnesota’s Department of Public Safety states the point directly: do not impede a motorcyclist’s legal right to filter.7Minnesota Department of Public Safety. Minnesota Motorcycle Safety Center
Deliberately blocking a filtering motorcyclist can go past a traffic infraction. Depending on what the driver does and what happens next, the conduct could support reckless driving charges or, if the rider is injured, assault with a vehicle. A driver who edges into the gap to make a point is creating the exact collision risk the filtering law was written to manage, and any resulting crash will land most of the fault on the driver. In stopped traffic in a filtering state, check mirrors before any lateral movement and leave the gap alone.