You were a passenger on a short trip across town, or you had unbuckled for a moment to reach something in the back seat, when another driver ran a red light and hit you. Weeks later the adjuster finds a line in the paramedic report, "unrestrained occupant," and suddenly the conversation is about you rather than the driver who caused the crash.
The seat belt argument is real, but it is narrower than insurers make it sound. California law treats it as a question of fact that the defense must prove, injury by injury.
Quick answer: Yes, you can still recover. Not wearing a seat belt does not bar a California injury claim and does not make you responsible for causing the crash. Vehicle Code section 27315(i) states that a seat belt violation does not establish negligence as a matter of law or negligence per se for comparative fault purposes, though negligence may be proven as a fact. Under CACI No. 712, the defense must prove that a working belt was available, that a reasonably careful person would have used it, that you did not, and that your injuries would have been avoided or less severe with it. If the defense proves all of that, your damages are reduced by your share of fault for the added harm, not eliminated.
Key Takeaways
- Not wearing a seat belt does not bar a California injury claim or shift fault for causing the crash.
- Vehicle Code section 27315(i) bars treating a seat belt violation as negligence per se.
- Under CACI No. 712 the defense must prove a belt would have avoided or lessened your specific injuries, usually with expert testimony.
- Any reduction is a comparative fault percentage applied to the added harm, not a fixed discount.
- A new five-step definition of "properly restrained" takes effect January 1, 2027.
What Does California's Seat Belt Law Require?
Vehicle Code section 27315 is the Motor Vehicle Safety Act. A person may not operate a motor vehicle on a highway unless the driver and all passengers 16 years of age or older are properly restrained by a safety belt, and a person 16 or older may not ride as a passenger on a highway unless properly restrained. Younger children are covered by the child restraint rules in Vehicle Code section 27360 and related sections, which place the duty on the parent, guardian, or driver.
A violation is an infraction, with a fine of not more than $20 for a first offense and not more than $50 for each later offense under section 27315(h). Penalty assessments add to those base amounts.
What changes on January 1, 2027?
Assembly Bill 435 (Stats. 2025, ch. 434) rewrote the definition of "properly restrained." The version in effect through December 31, 2026 requires the lap belt to cross the hips or upper thighs and the shoulder belt, if present, to cross the chest. The version that becomes operative on January 1, 2027 adopts a five-step test: the person sits all the way back against the seat, the knees bend over the edge of the seat, the shoulder belt crosses the center of the chest and shoulder rather than the neck, the lap belt sits as low as possible and touches the thighs, and the person can stay seated that way for the whole trip.
For injury claims, the practical effect is that "belted but not properly restrained" arguments, such as a shoulder belt tucked behind the back, have a more detailed statutory standard to point to starting in 2027.
Is Not Wearing a Seat Belt Automatically Negligence?
No. This is the most important point in the statute for an injured person. Section 27315(i) provides that in a civil action, a violation of the seat belt requirements does not establish negligence as a matter of law or negligence per se for comparative fault purposes, but negligence may be proven as a fact without regard to the violation.
In ordinary traffic cases, a statutory violation often triggers a presumption of negligence under Evidence Code section 669. The Legislature switched that presumption off for seat belts. The defense has to prove, as a fact, that you acted unreasonably.
The Court of Appeal explained how this works in Housley v. Godinez (1992) 4 Cal.App.4th 737. The statute bars an automatic, across-the-board reduction for anyone not wearing a belt, but it does not stop a jury from learning that the law exists and weighing it when deciding whether the plaintiff acted reasonably.
What Does the Defense Have to Prove?
The pattern jury instruction is CACI No. 712, Affirmative Defense: Failure to Wear a Seat Belt. The defendant must prove all of the following:
- A working seat belt was available.
- A reasonably careful person in the plaintiff's situation would have used it.
- The plaintiff failed to wear it.
- The plaintiff's injuries would have been avoided or less severe if the plaintiff had used it.
The fourth element is where most seat belt defenses succeed or fail. In Truman v. Vargas (1969) 275 Cal.App.2d 976, the Court of Appeal held that on the facts of that crash, expert testimony was required to prove what injuries the plaintiff would have suffered if belted, and Housley later described the defense burden the same way. In most crashes, the defense needs that kind of testimony. That usually means a biomechanical engineer or accident reconstructionist, and those opinions can be challenged.
Some injuries have nothing to do with a belt. A side impact that crushes the door into your leg, a lower extremity fracture from intrusion into the footwell, or whiplash that belted occupants suffer routinely may be the same or worse with a belt on. The defense does not get a reduction for those injuries just because you were unbelted.
How Much Can a Seat Belt Defense Reduce My Recovery?
There is no fixed percentage. California applies pure comparative fault, so a jury that accepts the defense assigns a percentage of responsibility to the plaintiff for the portion of harm the belt would have prevented, and damages are reduced accordingly. CACI No. 405 governs comparative fault of a plaintiff generally, and our post on comparative negligence in California explains how that reduction is calculated.
The driver who caused the crash remains responsible for causing it. A seat belt argument goes to the extent of your injuries, not to who ran the light.
Does It Matter if I Was a Passenger or a Child?
It can. CACI No. 712's directions for use note that the Motor Vehicle Safety Act applies to persons 16 and older, and to passengers 8 and older in certain vehicles such as taxis and limousines for hire, and that no case law has been found on whether persons under 16 can be found comparatively negligent for failing to wear a belt. Children are judged by the standard of care for minors in CACI No. 402. When a child is unrestrained, the more pointed question is often whether the driver or parent violated the child restraint statutes.
What About Medical Conditions?
Section 27315(g) exempts a passenger or driver with a physical or medical condition that would prevent appropriate restraint, if the condition is certified by a licensed physician and surgeon or licensed chiropractor stating the nature of the condition and why the belt is inappropriate. A person with that certification has a strong answer to the "reasonably careful person" element.
How Does the Insurer Find Out?
Through the collision report, the paramedic run sheet, emergency room notes, photographs of the belt, and sometimes the vehicle's event data recorder, which in many models records belt status. Seat belt marks across the chest and shoulder in medical records are evidence you were belted. If the report is wrong about your belt, our post on correcting a California collision report covers how to address it.
Frequently Asked Questions
Can the insurer deny my claim because I was not wearing a seat belt?
The seat belt defense does not excuse the other driver's fault in causing the crash. The insurer can argue that your damages should be reduced, but only by proving the elements in CACI No. 712, including that a belt would have prevented or lessened your injuries.
Will a seat belt ticket be used against me?
Section 27315(i) says a violation does not establish negligence as a matter of law or negligence per se for comparative fault purposes. The defense must still prove negligence as a fact.
Does the seat belt defense apply in Uber or Lyft rides?
The statute applies to passengers 16 and older in any motor vehicle on a highway, including rideshare vehicles. Rideshare claims have their own insurance structure, covered in our guide to Uber and Lyft accident claims in California.
Does the defense need an expert?
As a practical matter, yes. California cases such as Truman v. Vargas and Housley v. Godinez describe the defense burden as proving, with expert testimony, what injuries a belted occupant would have suffered, and without it the defense usually cannot carry its burden on the fourth element.
Does the seat belt defense apply to motorcycles?
No. The statute's definition of motor vehicle excludes motorcycles. Helmet issues are a separate question under Vehicle Code section 27803.
Told Your Seat Belt Ruins Your Claim?
Geller Legal Can Help.
Adjusters raise the seat belt defense early because it works on people who do not know its limits. The law puts the burden on the defense, requires proof about your specific injuries, and leaves the driver who caused the crash responsible for causing it.
Geller Legal | Personal Injury Attorneys examines the medical records, the vehicle, and the injury mechanics to test whether a belt would actually have changed anything, and answers the defense with evidence. Learn more about our California car accident practice.
We serve injured clients throughout California, with offices in Walnut Creek, Oakland, and Los Angeles. If an insurer is using your seat belt to cut your claim, call us at 213-770-4870 for a free, confidential consultation with Attorney Michael Geller.