How Is Fault Determined in a California Car Accident?

Who was at fault decides who pays after a car accident — but fault is rarely as simple as it feels at the scene, and it is not just whatever the police report says. In California it is built from evidence, it can be shared between drivers, and the percentage assigned to each person is often negotiable. Here is how it actually works. This is general information, not advice about your specific crash.

California is an at-fault, pure-comparative state

The driver who caused the crash (and their insurer) is responsible for the damages. But California uses pure comparative negligence, which means fault can be divided — one driver might be 80% responsible and the other 20%. Your recovery is reduced by your share of fault rather than eliminated, so even a partly-at-fault driver can recover. That is why every percentage point matters and why insurers fight over them.

The evidence that actually decides fault

• The police report and any traffic citations issued at the scene.
• Physical evidence — vehicle damage, points of impact, skid marks, and debris.
• Photos and video, including traffic and doorbell cameras (often overwritten within days).
• Witness statements from neutral third parties.
• Which driver violated a traffic law — running a light, an unsafe lane change, following too closely, or failing to yield.
• In serious cases, accident-reconstruction experts.

The police report is influential — but not the last word

A police report carries weight and is often where an insurer starts, but it is not binding. Officers usually arrive after the crash and piece it together, and they can get it wrong. Insurers and, ultimately, a jury can reach a different conclusion based on the full evidence. So a report that assigns you fault is not the end of the story — and one that favors you is not a guarantee.

How insurers assign fault — and why it's negotiable

After a claim, the insurer investigates and assigns a percentage of fault, and because every point it puts on you lowers what it pays, it has a built-in incentive to inflate your share. This is why adjusters ask leading questions and push for recorded statements. Fault is not fixed — it is an argument built from the evidence, which is exactly why preserving that evidence and being careful about what you say matters so much.