How to read a California traffic collision report

When law enforcement investigates a crash, the result is a traffic collision report — the CHP 555 form on state highways, or a local police or sheriff's version elsewhere. It is not the last word on fault, but insurers lean on it, so it is worth understanding what each part says.

It is general information, not legal advice.

The face sheet

The first page identifies the crash: date, time, and location; the investigating agency and officer; the parties (drivers, pedestrians, cyclists, sometimes parked-vehicle owners), each given a number; vehicle and insurance information; and a summary of injuries and property damage. Check the party numbers — the rest of the report refers to people as "Party 1," "Party 2," and so on.

The coded boxes

Much of the report is checkboxes and codes: the primary collision factor and its Vehicle Code section, movement preceding collision, type of collision, weather, lighting, road surface and conditions, and each party's sobriety. These translate to plain language on CHP collision report codes.

The narrative

The officer's written account: what each party and witness said, what the officer observed at the scene — skid marks, debris, vehicle rest positions, damage — and the officer's reconstruction of how the crash happened. Party and witness statements are usually summarized, not quoted. Note whether a party "declined to make a statement" or was not interviewed.

The diagram

A not-to-scale sketch showing the roadway, directions of travel, points of impact, and final positions. It is the officer's interpretation, and small details — the position of a limit line, which lane a vehicle is drawn in — can carry weight in a dispute.

The officer's opinion of fault

Through the primary collision factor and the narrative, the officer indicates who they believe caused the crash and which law was violated. This is an opinion, formed quickly, sometimes without all the parties' accounts. It is influential with insurers but it does not decide the claim — see comparative fault and how fault is decided in a car accident.

Citations and injury coding

The report notes any citation issued and codes each person's injury level on a standard scale from no injury to fatal. The injury codes feed state crash statistics and can differ from what later medical evaluation shows, because they reflect the scene only.

Getting a copy and correcting errors

• Request it from the investigating agency; involved parties, their lawyers, and their insurers are entitled to it.
• Expect a wait of about a week to several weeks.
• For a factual error — a misspelled name, wrong plate or policy number, wrong date — ask the agency to file a supplemental report.
• A disagreement about how the crash happened is usually addressed with evidence in the claim, not by changing the report.

Common questions

Is the police report evidence I can use in court?

Usually not directly. A California traffic collision report is generally not admissible at trial, and the officer's opinion of fault is not binding. But adjusters rely on it heavily when evaluating a claim, so what it says matters a great deal in practice.

What is the "primary collision factor"?

The officer's identification of the main cause of the crash, usually tied to a specific Vehicle Code section, and an indication of which party's action it was. It is the closest thing the report has to a fault finding.

The report has a factual error. Can it be fixed?

You can ask the investigating agency to add a supplemental report correcting a factual mistake — a wrong name, plate, date, or insurance detail. Officers rarely change their opinion of how the crash happened without new evidence.

How do I get a copy?

From the agency that investigated — CHP or the city or county police or sheriff. Involved parties and their representatives and insurers can request it. It usually takes a week or more to become available.