Auto Accidents
Not by itself. California defines lane splitting in Vehicle Code section 21658.1, and the CHP tells drivers it is legal, so the question in a claim is whether each person rode or drove with reasonable care. If a rider's own carelessness helped cause the harm, California's comparative fault rule reduces the rider's damages by that share instead of barring the claim.
Last updated October 5, 2026.
Motorcycle collisions are among the crashes we handle on our auto accident page, and lane splitting is the issue insurers raise most often when the rider was moving between cars. This page explains what the law and the California Highway Patrol (CHP) say about lane splitting, and how a rider's conduct is weighed against a driver's.
Vehicle Code section 21658.1, in effect since January 1, 2017, defines lane splitting as driving a motorcycle that has two wheels in contact with the ground between rows of stopped or moving vehicles in the same lane, on divided or undivided streets, roads or highways. The section does not list lane splitting as a violation. It allows the CHP to develop educational guidelines on lane splitting, in consultation with the DMV, Caltrans, the Office of Traffic Safety and a motorcycle safety organization.
The CHP's motorcyclist safety page states plainly, in its messages for other drivers, that lane splitting by motorcyclists is legal in California. It then gives safety tips for riders. Those tips say to consider the whole environment, including lane width, the size of nearby vehicles and the road, weather and lighting conditions. They warn that danger increases as overall speed and the speed difference between the motorcycle and traffic increase. They add that splitting between the far left lanes is typically safer, that riders should avoid splitting next to big rigs, buses and motorhomes, and that riding on the shoulder is illegal and is not lane splitting.
The tips are guidance, not statutes; the CHP says they are not guaranteed to keep a rider safe and that every rider is responsible for their own decisions. Legal also does not mean careless riding is excused, and an insurer may point to the tips when arguing about what a careful rider would have done.
| Rule | What it says | Source |
|---|---|---|
| Lane splitting defined | A two-wheeled motorcycle between rows of stopped or moving vehicles in the same lane | Veh. Code 21658.1(a) |
| Staying in a lane | Every vehicle must be driven as nearly as practical within a single lane and not moved from it until that can be done with reasonable safety | Veh. Code 21658(a) |
| Changing lanes or turning | No moving right or left until it can be done with reasonable safety, and only after an appropriate signal if another vehicle may be affected | Veh. Code 22107 |
| Basic speed law | No speed greater than is reasonable or prudent for weather, visibility, traffic and the road, and never a speed that endangers people or property | Veh. Code 22350 |
| Following distance | No following more closely than is reasonable and prudent | Veh. Code 21703 |
| Left turns | A driver turning left must yield to oncoming vehicles close enough to be a hazard | Veh. Code 21801(a) |
| Helmets | The rider and any passenger must wear a fastened, properly fitting safety helmet that meets state standards | Veh. Code 27803 |
| Blocking and doors | The CHP tells drivers that intentionally blocking or impeding a motorcyclist in a way that could cause harm is illegal, as is opening a door to impede one | CHP motorcyclist safety page |
California does not let a defendant escape responsibility just because the injured person was also careless. Under the Judicial Council's jury instruction CACI 405, a driver who claims the rider's own negligence contributed to the harm must prove two things: that the rider was negligent, and that the rider's negligence was a substantial factor in causing the rider's harm. If the driver proves both, the rider's damages are reduced by the jury's percentage of the rider's responsibility. The claim is not thrown out.
So it is not enough to show that the rider was lane splitting. The driver must show that the way the rider rode was careless and actually contributed to the injuries. A rider moving slowly between stopped cars is in a very different position from one weaving at high speed through moving traffic.
When more than one person may share the blame, CACI 406 asks the jury to assign percentages of responsibility to each person, totaling 100 percent, and to find the rider's total damages separately, without considering those percentages. Civil Code section 1431.2 then splits the damages in two ways. Each defendant's share of non-economic damages, such as pain and suffering, is limited to that defendant's percentage of fault. Economic damages, such as medical bills and lost earnings, are not covered by that limit.
Traffic statutes play a special role. Under CACI 418, if a statute was violated and the violation was a substantial factor in causing the harm, the jury must find the violator negligent unless the violation was excused. That works in both directions: a driver's unsignaled lane change under section 22107 can establish the driver's negligence, and a rider's unsafe speed under section 22350 can establish the rider's.
These facts most often move the percentages.
The basic speed law in section 22350 applies to riders and drivers alike, and CACI 706 tells jurors that whether a speed is reasonable depends on traffic, weather, visibility and road conditions. The CHP's warning that danger rises with the speed difference gives that question a practical edge: passing stopped traffic at a modest speed is judged very differently from passing moving traffic much faster than it is going.
Many lane splitting crashes happen when a car changes lanes or drifts toward the line. Section 21658(a) requires every vehicle to stay as nearly as practical within a single lane and not move out of it until it can do so with reasonable safety, and section 22107 adds the signal requirement.
The statutory definition covers a motorcycle with two wheels in contact with the ground, between rows of vehicles in the same lane. Riding on the shoulder is not lane splitting, according to the CHP, and a three-wheeled machine falls outside the definition. Many motorcycle crashes are not lane splitting cases at all: a driver turning left across the rider's path must yield to oncoming vehicles close enough to be a hazard (section 21801(a); CACI 704).
Section 27803 requires the rider and any passenger to wear a safety helmet that meets state standards, fastened and properly sized. The 2026 CACI text contains no instruction written specifically for helmets, so a defense argument that the lack of a helmet made a head injury worse goes through the general comparative fault test in CACI 405, including its requirement that the rider's conduct was a substantial factor in causing the harm. A helmet argument does not touch injuries a helmet could not have prevented, such as a broken leg.
The CHP's messages for drivers say that intentionally blocking or impeding a motorcyclist in a way that could cause harm is illegal, and so is opening a vehicle door to impede one. Conduct like that shifts the focus to the driver, so witness names and video matter.
If the vehicle belonged to a city, county or state agency, or a road defect played a part, a written government claim is due within six months. Our page on claims against Glendale or Los Angeles County explains where to file. If a big rig or a company van was involved, our page on crashes with trucks and company vehicles explains when the employer or owner shares responsibility.
For example, imagine a hypothetical rider heading west on the 134 near Glendale during evening traffic. Cars in the two left lanes are moving at about 15 miles per hour, and she is splitting between them at about 25, wearing a helmet and a bright jacket. A driver in the far left lane moves right without signaling to take a gap, and his mirror strikes her handlebar. She goes down and breaks her wrist.
The driver's insurer says she caused the crash by lane splitting. Under the rules above, that is not the end of the question. Lane splitting itself is legal; the driver had to stay in his lane until he could move with reasonable safety and to signal first (sections 21658(a) and 22107). The insurer would have to prove that her own riding was careless and was a substantial factor in causing her injury, perhaps by arguing that a 10 mile per hour speed difference was too much for that stretch of road.
As an illustration of the arithmetic only: if a jury found her total damages to be $100,000 and assigned her 20 percent of the responsibility, her recovery from the driver would be reduced to $80,000 under CACI 405. Whether any percentage belongs to her depends on evidence such as witness accounts, video and the damage to both vehicles.
Section 21658.1 defines lane splitting on both divided and undivided streets, roads and highways, and the CHP says it is legal. The CHP's tips still advise against it next to large vehicles and say that riding on the shoulder is illegal and is not lane splitting.
Possibly. Speed is one factor in whether your riding was careless, and under CACI 405 any share of fault assigned to you reduces your damages rather than barring them.
No. Section 27803 requires a helmet, but under the general comparative fault rule the defense must show that not wearing one was a substantial factor in causing your injuries. A helmet argument can reach only injuries a helmet would have prevented or lessened, not every injury from the crash.
Yes. A passenger on the motorcycle may have claims against the driver who caused the crash and, in some cases, against the rider. Our page on whose insurance pays a passenger explains which policies may apply.
No. Section 21658.1 covers a motorcycle that has two wheels in contact with the ground. Every vehicle, of any kind, must also follow section 21658(a) and stay within a single lane as nearly as practical.
Then the family or the estate may bring the claim, and the rules on who may sue and what may be recovered are different. Our page on wrongful death and survival claims explains them.
Generally two years from the crash for an injury lawsuit (Code of Civil Procedure section 335.1). A claim against a city, county or state agency must be presented within six months (Government Code section 911.2).
We gather the report, photographs, video and witness accounts that show how the crash happened, respond to the lane splitting argument with the actual rules, and pursue the coverage that applies. Riders in the area can read about local offices on our Glendale personal injury lawyer page. Call (818) 244-9000 or request a consultation.
Our Glendale team can review how the crash happened, answer the lane splitting argument and explain what coverage may apply.
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