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Accident Investigation & Evidence in California

Posted by attorney John Demas

When an accident occurs, the most common source of information is a “ Traffic Collision Report" prepared by the California Highway Patrol or a local police agency. If you are incapacitated by injuries at the scene of a collision, this report may later be the only way to identify and locate the other parties involved, any witnesses, and insurance information.

Beyond this basic information, the quality and accuracy of the report will vary depending on the effort of the investigating officer. He will usually interview all involved drivers and witnesses and summarize their statements in the report. He will usually note the location and severity of the damage to the vehicles and whatever physical evidence exists at the scene. In more severe collisions, collisions involving a possible crime, or where the issue of fault is clearly in dispute, the investigating officers may take photos of the scene and vehicles or measure the distances of skid marks and other physical evidence. The report sets forth the officer’s conclusion as to which party or parties the officer believes are at fault and which vehicle code sections were violated.

Insurance companies will usually follow the conclusion of the investigating police officer in determining liability. If the police officer concludes, that the other party is at fault based on independent witness statements or physical evidence, his insurance company will typically accept liability. However, if the statements are conflicting – for instance both drivers claimed to have had a green light at an intersection, there are no witnesses, and the officer chose to believe you over the other party – the insurance company may refuse to accept liability.

In many cases, especially if there is some dispute as to how the collision occurred, it is advisable to get a more complete statement from a witness. Officers investigating a collision are subject to many distractions, such as clearing the scene for traffic, and may be limited in the amount of time they have to spend with witnesses at the scene. We have found that when interviewed, witnesses often add critical facts that were not noted in the officers’ statements, or clarify statements in a way that is helpful to a case.

When the police do not investigate the collision, it is up to each driver to obtain and preserve information. This can be difficult if you are disoriented, flustered or hurt immediately after a collision. If possible, get the full name, address, phone number, driver’s license number, license plate number and insurance name and policy number of the involved drivers. Also, try to get the names and contact information of any witnesses, even if it seems like a clear case of fault against the other driver. More than one responsible driver has admitted fault at the scene of an accident only to change his or her story to the insurance company later. If possible, take photographs of the damage to the vehicles and their license plates, the scene of the collision, and any physical evidence such as skid marks.

Insurance companies have an advantage over the average person when it comes to investigation. The adjuster has been trained to investigate, has access to the company databases and has the ability to take recorded statements of the parties and witnesses. Adjusters from the other party’s insurance company may contact you after a collision and ask for a recorded statement about the accident and your injuries. While seemingly harmless, we advise against such statements since they could potentially be used against you if a dispute as to fault or the extent of your injuries arises. The questions asked in these statements are often ambiguous or very general. Why take a risk that your answer can be used out of context, especially when there is a police report that establishes what happened?

While insurance companies typically rely on the police report in determining who was at fault, it not binding in a civil lawsuit. In most cases, the opinions of the investigating officer about who caused a collision are inadmissible in a court of law as hearsay. Also, investigating officers routinely make mistakes in collecting and observing evidence. Sometimes, inaccurate measurements are taken, witnesses are misquoted or missed altogether, or the officer’s evaluation of a witness or other evidence is simply incorrect. In these cases, further investigation can reveal evidence that leads to a different conclusion as to fault. In some cases, accident reconstruction experts can be retained to evaluate the available evidence and provide the correct interpretation as to which driver’s conduct caused or contributed to the collision.

Because witnesses, memories and physical evidence tend to disappear over time, it’s essential that you make efforts to preserve evidence as soon as possible after a collision. If you believe that there will be any issues with liability or there will be a need for follow-up investigation, it is a good idea to at least consult with a qualified personal injury attorney, visit

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