The helmet law and your claim

California requires every rider and passenger to wear a helmet. What that means for a claim is more limited than either side tends to assume, and parts of it are genuinely unsettled. This page says which parts. This is general information, not legal advice.

The requirement

A driver and any passenger must wear a safety helmet meeting requirements established pursuant to Vehicle Code section 27802 when riding on a motorcycle, motor-driven cycle, or motorized bicycle. The helmet must be properly fitted and fastened with the retention straps.

It is universal — no age exemption, no experience exemption, no exemption for short trips. California is among the states that require helmets for all riders rather than only for those under a certain age.

Sources: Veh. Code, § 27803 (helmet required for driver and passenger). Last amended Stats. 1997, ch. 710, effective January 1, 1998.

What a violation does — and does not do

Three things it does not do. It does not bar a claim. It does not make a rider at fault for a collision someone else caused. And it says nothing about how the crash happened.

What it does is give the defence a comparative fault argument: that the rider's own conduct contributed to the severity of their injuries. In California a claimant's share reduces the recovery in proportion rather than barring it, however large that share is.

Comparative fault.

The limit on that argument, and its uncertainty

The sensible boundary is that a safety-equipment argument should reach only the harm the missing equipment actually caused or worsened — head and facial injuries, not fractures, internal injuries, or road rash. Here is where that principle comes from, and here is the honest caveat.

California law is settled for seat belts. A defendant raising the seat belt defence must prove not only that a reasonably careful person would have worn one, but that the plaintiff's "injuries would have been avoided or less severe" had they done so — and the courts require expert testimony on what those injuries would have been. The reduction is measured by the difference the belt would have made.

That line rests on Vehicle Code section 27315(i), which expressly addresses failure to wear a seat belt. Section 27803 contains no equivalent provision, and no published California decision has applied the seat belt causation limit to motorcycle helmets. There is no CACI instruction for a helmet defence as there is for seat belts.

So the position is: the analogy is strong, the reasoning transfers cleanly, and a defence should be held to the same proof — but treat the boundaries as arguable rather than fixed, and expect a defendant to argue for more than the seat belt cases would allow.

Sources: CACI No. 712 (affirmative defence — failure to wear a seat belt; element 4 requires proof the injuries "would have been avoided or less severe"), Judicial Council of California Civil Jury Instructions (2026 edition); Housley v. Godinez (1992) 4 Cal.App.4th 737, 747; Franklin v. Gibson (1982) 138 Cal.App.3d 340, 343; Veh. Code, § 27315(i). Applied to helmets by analogy — see the caveat above.

Non-compliant helmets

A helmet that does not meet the federal standard — a novelty shell, a damaged helmet, one worn unfastened — invites the same argument as no helmet. The defence still has to connect it to the injuries actually suffered, and doing that requires the helmet itself.

Which is the practical point: keep the helmet. Its condition, the location and depth of impact marks, whether the liner compressed, and whether the strap was fastened are all readable from the object and from nothing else. It is routinely discarded at the hospital or left at the scene.

Gear and evidence.

If you were wearing one

Then this argument is unavailable, and the fact is worth establishing early with a photograph of the helmet showing the damage. A helmet that did its job is also affirmative evidence of the force involved, which cuts against a defence suggesting the impact was minor.

Common questions

Who has to wear a helmet in California?

Everyone. A driver and any passenger must wear a safety helmet meeting the standard established under Vehicle Code section 27802 when riding on a motorcycle, motor-driven cycle, or motorized bicycle. There is no age exemption and no experience exemption.

If I was not wearing one, is my claim over?

No. A helmet violation does not bar a claim and does not decide fault for the crash. It is raised as comparative fault, which reduces rather than eliminates, and it has to be connected to actual harm rather than asserted.

Can it reduce damages for injuries that have nothing to do with my head?

That is the argument a rider should resist, and the analogy that supports resisting it is the seat belt defence — where a defendant must prove what the injuries would have been with the belt, so the reduction reaches only the harm the omission actually caused. Be aware that no published California decision has settled that this transfers to helmets.

What if my helmet was not DOT compliant?

Expect it to be raised the same way as not wearing one, and expect the same requirement of proof — that the non-compliance made a difference to the injuries actually suffered. The helmet itself becomes important physical evidence, so keep it.