Written and reviewed by Josh Kohanim, Esq., California Bar No. 328609 · Reviewed
In this guide
A rider hit while moving between rows of traffic in Los Angeles County, on the 101 through the Valley, on the 405 over the pass, or at a signal on Wilshire, is judged by the ordinary standard of care, because the statute sets no other. For deadlines, coverage and injuries, start at our Los Angeles motorcycle accident lawyer page.
What the lane splitting law leaves out
Section 21658.1 has two working parts. Subdivision (a) defines lane splitting as driving a motorcycle with two wheels in contact with the ground between rows of stopped or moving vehicles. Subdivision (b) says the Department of the California Highway Patrol may develop educational guidelines relating to lane splitting in a manner that would ensure the safety of the motorcyclist and of the drivers and passengers around them. The section was added by Assembly Bill 51 and took effect on January 1, 2017.
The section contains no maximum speed, no maximum speed differential, no lane restriction, no penalty, and no language making the practice lawful either. California's own DMV describes the same silence in the Motorcyclists Guide, which says California law does not allow or prohibit motorcycles from passing other vehicles proceeding in the same direction within the same lane. A defense lawyer who wants to call you negligent has to prove it with facts, because there is no code section to point at.
The CHP publishes tips rather than rules
Under Vehicle Code sections 2930 to 2935, the Highway Patrol runs the California Motorcyclist Safety Program. Its program page states that more than 1,500,000 riders have been trained since the program began in July 1987, as of June 2025, and that the Motorcyclist Training Course runs 15 hours, 5 in a classroom and 10 on a bike. The same agency publishes lane splitting safety tips: avoid splitting next to large vehicles such as big rigs, buses and motorhomes, splitting between the far left lanes is typically safer than between other lanes, and lane splitting can be dangerous and extreme caution should be exercised.
Every word of that is guidance. None of it creates an offense, and a rider who splits between the middle lanes has broken no rule. An insurance adjuster will still quote the tips back at you as though they were a code section. They are a reasonable-care argument dressed as a citation, and they are answered with the speeds, the gap, and what the driver did.
| Source | What it does | What it does not do |
|---|---|---|
| Vehicle Code 21658.1 | Defines lane splitting and authorizes CHP guidelines | Permit it, prohibit it, or set any speed |
| DMV Motorcyclists Guide | States that California law does not allow or prohibit passing within the same lane | Create a standard a rider can violate |
| CHP lane splitting safety tips | Advise on lane choice, large vehicles and caution | Carry any penalty or bind a jury |
| CACI Nos. 400, 401 and 700 | Set the reasonable-care standard both parties are judged by | Treat a rider differently from a driver |
| Vehicle Code 22107 | Requires a lane change to be safe and signaled | Apply only to cars |
How fault is decided without a rule
A Los Angeles jury in a lane splitting case hears the instructions it hears in any collision. CACI No. 400 sets out the elements of negligence, CACI No. 401 defines the standard of care, and CACI No. 700 tells the jury a driver must use reasonable care, keep a lookout, and control the speed and movement of the vehicle. Each applies to the rider and the driver in identical terms.
The driver's conduct usually has a statute behind it, and that is where these cases are won. Vehicle Code section 22107 says no person shall turn a vehicle from a direct course or move right or left upon a roadway until the movement can be made with reasonable safety, and then only after giving an appropriate signal if any other vehicle may be affected. The jury gets CACI No. 705 on that section. A driver who drifted into the gap without a mirror check and without a blinker has violated a statute written to prevent this collision.
| The insurer's version | What answers it |
|---|---|
| The rider came out of nowhere | Helmet camera video, and the driver's own sight lines photographed from the driver's seat |
| The rider was going far too fast | Video timestamps, traffic flow speed from nearby cameras, a reconstruction from damage and rest positions |
| The gap was too narrow to pass | Lane width measurements, vehicle widths, and scene photographs before the cars move |
| The rider hit the car, so the rider caused it | Where on the car the contact landed. A mirror or a front door strike means the car moved into the rider |
| Lane splitting is reckless | There is no statute to violate, and CACI No. 418 gives the defense no presumption |
Evidence that wins a lane splitting case
- Your own camera. Helmet and handlebar cameras record the gap, the traffic speed, and the moment the car moved. Pull the memory card before you do anything else with the device.
- Contact geometry. Damage to the car's left front fender or mirror puts the car in your lane space. Damage to the car's rear quarter tells a different story. Photograph both vehicles before either is moved.
- The car's turn signal bulb. A filament that was hot at impact deforms differently from a cold one. It is a small piece of physical evidence that answers a driver who insists the blinker was on.
- Traffic flow speed. If the cars beside you were nearly stopped, a modest speed reads as a modest speed differential, which is the number the whole argument turns on.
- Freeway and business cameras. Most overwrite within days, and on the 101 and the 405 the useful angles usually belong to a private business.
- The driver's first words. Officers write down what drivers say at the scene, and that version rarely matches the recorded statement three weeks later.
When the usual answer breaks down
Section 21658.1 is narrower than most riders assume, and several common maneuvers sit outside it entirely. None of these ends a claim. Each one changes the argument you should expect.
- Three wheels on the ground. The definition covers a motorcycle with two wheels in contact with the ground. A trike, a sidecar rig or a three-wheeled machine is not doing what the statute describes, so the statute has nothing to say about it either way.
- Passing on the shoulder or between traffic and the curb. The statute describes riding between rows of vehicles in the same lane. A shoulder is a different maneuver with different rules, and this section does not reach it.
- Filtering to the front at a red light. The DMV groups filtering with lane splitting and lane sharing, and the same silence applies. Expect the insurer to argue you appeared beside a car that had already committed to a right turn.
- Splitting past a big rig or a bus. Legally identical, and factually much worse for the rider. The CHP's own tips warn against it, and the defense will read that warning to the jury.
- A large speed differential. Nothing makes 40 miles per hour past stopped traffic unlawful by itself. It makes the reasonable-care argument hard, and it is where comparative fault takes a real share.
- A rider under 21 without the training course. That is a licensing issue with the DMV. It does not excuse the driver and it does not decide fault.
What to do if you were splitting
Say nothing about your speed until someone has watched the video, and give no recorded statement while you are on pain medication. Photograph both vehicles and the lane before anything is towed. Then get the preservation letters out, the written demands that the footage and the car be kept, because the cameras overwrite in days and the other car goes to a body shop inside a month.
Two related questions come up in nearly every one of these files. If a driver turned across your path rather than drifting into it, our left turn and right of way accidents page covers the statute and the proof. If the report notes no helmet, our helmet law and your claim page explains what that can and cannot cost you. An insurer handles a rider file like a car accident claim until it needs an excuse, so expect the tone to change the day liability looks clear.
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