The first priority is safety. The second is preservation.

A serious crash scene changes minute by minute. Vehicles move. Debris is swept away. Witnesses leave. Video is overwritten. Tow operators take possession. Phones lose data. The first investigation decisions therefore occur while emergency needs are still being addressed.

Priority 1

Protect life

Call 911 where needed, identify injuries, follow emergency directions and avoid creating another roadway hazard.

Priority 2

Identify people

Drivers, occupants, pedestrians, witnesses, owners, employers and responding agencies can all become essential evidence sources.

Priority 3

Preserve what will disappear

Record vehicle positions, roadway conditions, traffic controls, weather, debris, witnesses and available video as safely as circumstances permit.

Never collect evidence by creating a second danger. Do not stand in active traffic, interfere with emergency responders or enter an unsafe roadway to take photographs.

California imposes immediate statutory duties after a collision

Situation	California rule
Injury or death	Vehicle Code §20001 requires the driver to immediately stop and fulfill the information and assistance duties of §§20003 and 20004.
Property damage only	§20002 requires stopping at the nearest place that will not impede traffic or otherwise jeopardize motorists.
Exchange information	§§20002 and 20003 require specified driver, owner, vehicle and identification information.
Injured person	§20003 requires reasonable assistance, including arranging medical transportation where apparently necessary or requested.
Injury/death report	§20008 generally requires the driver of a non-common-carrier vehicle to make or cause a written report to CHP or appropriate city police within 24 hours.

Important property-damage rule: §20002 expressly says that moving the vehicle to the safer location required by that section does not affect the question of fault.

Police reporting and DMV reporting are separate obligations

California's DMV reporting system serves a different purpose from the investigating police or CHP report.

Immediately Stop, identify injuries, exchange required information and comply with applicable §§20001–20004 duties.

24 hours §20008 written-report requirement for qualifying injury/death crashes.

10 days General §16000 / SR-1 deadline for a qualifying DMV-reportable crash.

Early Preserve video, vehicles and electronic evidence before routine destruction or overwriting.

When is an SR-1 generally required?

Injury

Any bodily injury triggers the ordinary §16000 reporting requirement.

Death

A fatal crash is reportable under §16000.

Property damage

Damage to the property of any one person exceeding $1,000 triggers the ordinary reporting requirement.

The SR-1 is separate. California DMV currently instructs that a qualifying SR-1 must be filed within 10 days even if police, CHP or the insurance company already received a report.

Government-vehicle exception: §16000(b) excludes a vehicle owned or leased by, or under the direction of, specified federal, state and local governmental entities from that subdivision's SR-1 requirement. Government crashes still require the separate analysis in Guide 16.

The police report is the beginning of the investigation—not the verdict

A collision report can supply identities, statements, measurements, diagrams, witnesses, observations and an officer's reconstruction. It should be obtained and audited against the underlying evidence.

Audit identities

Driver, registered owner, passengers, witnesses, employers and insurance should be independently confirmed.

Audit diagram

Compare lane geometry, vehicle movements, impact points and final rest against photographs and available video.

Audit statements

Determine whether quoted or summarized statements match bodycam, recordings or later witness accounts.

Audit causation

An officer's listed primary collision factor is important investigative material but is not itself a civil judgment allocating damages.

Obtaining a CHP report: CHP currently allows a proper party of interest to request a CHP crash report/investigation through its Crash Portal or through the CHP 190 process.

Access and admissibility are different questions. Vehicle Code §20012 provides access to required report materials for persons with a proper interest. Section 20013 separately limits use of specified required accident reports as trial evidence.

Photograph the scene from outside in

Good crash photography preserves context before focusing on individual marks.

Establish the location. Photograph the intersection, road segment, addresses, mile markers and recognizable landmarks.

Photograph each driver's approach. Record what the roadway, signals, curves, vegetation and sight lines look like from each direction.

Preserve final rest. Photograph each vehicle's position relative to lanes, shoulders, medians, sidewalks and fixed objects.

Record physical marks. Tire marks, gouges, scrapes, fluid, debris, broken glass and displaced objects can help establish movement and impact.

Record traffic control. Signals, signs, pavement markings, turn restrictions, bicycle markings and pedestrian-control devices.

Record conditions. Lighting, weather, wet pavement, glare, construction, standing water and sight obstructions.

Use both wide and close photographs. A close image of a tire mark is far more useful when another photograph shows exactly where that mark was located in relation to the road and vehicles.

Independent witnesses can disappear faster than physical evidence

Identify

Full name, telephone, email and enough information to locate the witness later.

Locate the viewpoint

Where exactly was the witness standing, driving, sitting or looking?

Separate seeing from assuming

Did the witness see the signal, impact or speed—or infer it from what happened immediately afterward?

Preserve the first account

Early recollection can be valuable before repeated discussion causes memories and assumptions to blend.

Do not tell the witness what the evidence “shows” before obtaining the witness's independent recollection.

Search for video before it is automatically overwritten

A camera that did not capture the point of impact may still establish approach speed, signal status, traffic conditions or vehicle identity.

Dashcam

Vehicles involved, witnesses, buses, trucks and nearby rideshare vehicles may carry cameras.

Businesses

Fuel stations, banks, stores, warehouses and parking facilities often record adjacent roadways.

Homes

Doorbells and residential security systems may capture streets and intersections.

Government

Traffic cameras, transit cameras, police dashcam/bodycam and public building cameras may exist.

Commercial fleets

Trucks and fleet vehicles increasingly use forward-facing and driver-facing camera systems.

Phones

Occupants and bystanders may have photographed or recorded events immediately before or after impact.

Act quickly. Many systems continuously overwrite recordings under routine retention schedules.

The vehicles are physical evidence

Vehicle inspection can establish both collision mechanics and injury mechanisms.

Exterior damage

Crush depth, direction, paint transfer, scrape marks, wheel damage and contact height can help identify how impact occurred.

Interior evidence

Airbags, seat position, belt use, steering wheel, dashboard, glass and occupant-contact evidence can assist injury reconstruction.

Mechanical condition

Tires, brakes, steering, lighting and other components may require preservation where mechanical failure is alleged.

Identity

Photograph VIN, plate, make/model, mileage and identifying fleet, rental or commercial markings.

Do not allow a potentially important vehicle to disappear into salvage without first deciding whether inspection or electronic download is necessary.

Modern vehicles may contain objective pre-impact and impact data

Vehicle Code §9951 governs manufacturer-installed devices commonly described as event data recorders or sensing and diagnostic modules.

Speed

Section 9951 identifies vehicle speed and direction as information recording devices may capture.

Braking

The statute expressly includes brake performance and whether brakes were applied before an accident.

Steering

Steering-performance information can be recorded on qualifying systems.

Seat-belt status

Section 9951 includes driver seat-belt status among listed data.

Travel information

Certain systems may record location or travel-history information.

Crash transmission

Some connected systems can transmit collision information to a communications service.

California restricts EDR retrieval. Under §9951, someone other than the registered owner generally needs a statutory basis such as owner consent or a court order to retrieve the data.

Preservation comes before download. Secure the vehicle, ownership/consent issues and chain of custody before attempting an EDR retrieval.

Do not treat the EDR as the only digital evidence

Source	Potential evidence
Vehicle EDR	Speed, braking, steering, restraints and other crash-event data depending on the vehicle/system.
OEM telematics	Location, crash notification, vehicle status and connected-service data.
Infotainment	Paired devices, navigation destinations, calls or other data depending on system capabilities.
Mobile phone	Calls, texts, application use, photographs, video, location and timestamps.
Commercial ELD	Driver duty status, movement and motor-carrier operational data.
Fleet telematics	GPS, speed, hard braking, acceleration and dispatch information.
TNC platform	Login, ride request, acceptance, passenger trip and completion status.

Investigate the road as carefully as the drivers

Driver conduct can coexist with a roadway, signal, construction or maintenance condition that contributed to the collision.

lane width
shoulder width
curve radius
road grade
sight distance
traffic signs
signal heads
signal timing
lane arrows
crosswalks
bicycle facilities
pavement condition
potholes
standing water
construction
temporary traffic control
lighting
vegetation
visual obstructions
warning devices

If a government roadway condition may have contributed, review Guide 16 immediately. Government Claims Act deadlines can expire long before a conventional crash lawsuit deadline.

A Vehicle Code violation can matter—but only when it caused the kind of harm the law was designed to prevent

Evidence Code §669 establishes California's negligence-per-se presumption when all statutory elements are satisfied.

Identify the statute or regulation. What precise traffic or safety rule was allegedly violated?

Prove the violation. Use physical, electronic, witness and other admissible evidence.

Prove causation. The violation must proximately cause the death, injury or property damage.

Match the occurrence. The harm must arise from an occurrence the rule was designed to prevent.

Match the protected class. The injured person must fall within the class the law was designed to protect.

A violation is not a shortcut around causation. Lack of insurance, licensing irregularities or unrelated regulatory violations do not become crash fault merely because they existed.

The injury investigation begins with the impact chronology

Medical causation is strongest when the crash mechanics, symptom onset, examination findings, diagnostic testing and treatment chronology can be compared rather than considered in isolation.

At the scene

Record loss of consciousness, confusion, head strike, pain, neurological complaints, bleeding and visible injuries.

EMS

Preserve ambulance records, vitals, Glasgow Coma Scale where used, immobilization and reported symptoms.

Emergency care

Identify diagnoses, imaging, examination findings, discharge instructions and referrals.

Evolution

Track symptoms and functional limitations that become clearer over the following hours and days.

Do not convert “no ambulance” or “no immediate pain” into a medical conclusion. The significance of delayed symptoms depends on the injury and competent medical evidence.

Special crash types require additional evidence branches

Work / commercial

Employer, dispatch, time records, ELD, fleet telematics, motor-carrier identity, maintenance and commercial insurance.

Rideshare

Platform login, request acceptance, pickup, passenger entry/exit, trip completion and logoff.

Government

Agency identity, employee assignment, dashcam/bodycam, CAD, emergency status, pursuit records and Government Claims Act deadlines.

Rental / borrowed vehicle

Vehicle owner, permission, rental agreement, driver's own policy and insurance-priority analysis.

Vehicle defect

Preserve the vehicle, failed component, repair history, recalls, diagnostic information and electronic data.

Autonomous / ADAS

Preserve system status, warnings, sensor information, software, telematics and driver-interaction evidence where available.

Evidence preservation should identify the evidence—not merely say “preserve everything”

A focused preservation notice can identify categories and systems that otherwise may be destroyed through routine business processes.

Vehicle

No salvage, destruction, material alteration or destructive testing before inspection issues are resolved.

Electronic data

EDR, telematics, GPS, ELD, app data, diagnostic data and camera recordings.

Documents

Maintenance, dispatch, training, employment, rental, ownership and insurance records.

Evidence Code §413: where willful suppression of relevant evidence is established, the trier of fact may consider that conduct in deciding what inferences to draw.

A preservation demand does not itself give a private person the right to access protected electronic data. Consent, discovery, court process, privacy law and other applicable rules must still be followed.

Build one master timeline from independent clocks

A reliable chronology is often more useful than competing narratives.

Clock	Potential timestamp
911	Call initiation, answer, dispatch and emergency-response times.
Video	Vehicle approach, signal sequence, collision and post-impact events.
EDR	Pre-impact event sequence depending on vehicle/system.
Telematics	Location, movement, crash notification and operational events.
Phone	Calls, messages, apps, photos and navigation events.
Police CAD	Call receipt, unit assignment, arrival and incident events.
EMS / hospital	Assessment, transport, arrival and first documented symptoms.
Tow / salvage	Removal, storage, transfer and vehicle-disposition chronology.

Use fixed timestamps to test memory. Witness recollection becomes more useful when compared against objective time markers rather than treated as the only chronology.

Crash investigation includes finding every policy connected to the event

The investigation is incomplete if it explains how the crash happened but never identifies the insurance capable of responding.

driver liability policy
vehicle-owner policy
household policies
employer commercial auto
hired/nonowned auto
umbrella
excess policy
TNC insurance
rental insurance
government entity
motor-carrier coverage
claimant UM/UIM
MedPay

Liability investigation and coverage investigation should proceed together. Facts such as vehicle ownership, employment, app status and permissive use can determine both who is liable and which policy applies.

California citizen crash-investigation workflow

Protect people first. Address medical and roadway safety before evidence collection.

Call the appropriate emergency or law-enforcement agency. Create the correct official response where circumstances require it.

Identify every driver, occupant and vehicle owner. Photograph licenses, registration and insurance where safely and lawfully possible.

Identify independent witnesses. Obtain contact information before they leave.

Photograph the scene broadly. Preserve road geometry and vehicle positions before focusing on details.

Photograph physical evidence. Impact areas, debris, marks, roadway conditions and traffic controls.

Identify every possible camera. Dashcam, business, residential, traffic, transit and police systems.

Preserve the vehicles. Decide whether inspection, EDR download or mechanical examination is needed before repair or salvage.

Preserve electronic evidence. EDR, telematics, phones, GPS, infotainment and platform data where relevant.

Complete statutory reporting. Review §§20001–20008 and the separate §16000 / SR-1 requirements.

Obtain the complete law-enforcement investigation. Report, diagrams, photographs, video, supplements and related available materials.

Audit the police report. Compare conclusions with photographs, video, statements and electronic evidence.

Document injury chronology. Scene symptoms → EMS → emergency department → follow-up → diagnosis.

Determine whether a special branch applies. Work, commercial, rideshare, rental, government, roadway or product issue.

Find every insurance policy. Driver, owner, employer, umbrella, excess and first-party coverage.

Build a master chronology. Normalize all available electronic and documentary timestamps.

Identify each actor's legal duty. Apply the actual Vehicle Code and other governing rules.

Determine breach. What specifically did each actor do or fail to do?

Require causation. Separate conduct that merely looks bad from conduct that actually contributed to the collision or injury.

Only then allocate comparative fault. Fault percentages are the product of the investigation, not its premise.

Crash investigation file

police / CHP report
supplemental reports
CHP 190 request if applicable
SR-1
driver licenses
vehicle registrations
insurance cards
scene photographs
vehicle photographs
roadway photographs
drone imagery where lawful/appropriate
witness list
witness statements
911 audio
CAD records
dashcam
bodycam
traffic video
business surveillance
residential surveillance
EDR data
EDR download report
vehicle telematics
infotainment data
phone records
GPS records
TNC platform data
ELD data
fleet telematics
tow records
salvage records
maintenance records
tire records
brake records
recall information
traffic-signal timing
road maintenance records
construction traffic-control plan
weather information
EMS records
emergency-room records
diagnostic imaging
preservation letters
proof of preservation delivery
driver policy
owner policy
commercial policy
umbrella/excess policy
UM/UIM policy

Common mistakes

“Moving the cars proves I disturbed the scene.”

For a property-only crash, §20002 requires movement to a nearby safe location when necessary and expressly states that compliant movement does not affect fault.

“The police made a report, so I do not need an SR-1.”

Wrong for an otherwise qualifying crash. DMV states that SR-1 reporting is separate from police, CHP and insurance reporting.

“The officer said Driver A was at fault, so the civil case is finished.”

No. The report is investigative evidence. Civil liability requires legal and evidentiary analysis.

“The vehicle has already been photographed, so it can be salvaged.”

Photographs may not preserve EDR data, mechanical evidence, crush measurements or occupant-contact evidence.

“EDR data belongs to whoever has possession of the vehicle.”

No. California §9951 restricts retrieval and gives the registered owner an important statutory role.

“No skid marks means the driver never braked.”

Modern ABS-equipped vehicles may brake heavily without leaving traditional locked-wheel skid marks. Electronic and physical evidence must be considered together.

“No ambulance means no serious injury.”

That is not a medical conclusion. Evaluate actual symptoms, diagnosis, medical findings and chronology.

“One eyewitness settles the case.”

Test every account against viewpoint, timing, video, physical evidence and other objective sources.

“The traffic violation automatically establishes liability.”

Evidence Code §669 still requires the statutory violation to have the required causal and protective relationship to the injury.

“I can look for surveillance video later.”

Often not. Routine overwriting can destroy the best evidence within days.

“The insurance investigation can wait until fault is decided.”

No. Ownership, employment and app status often determine liability and insurance simultaneously.

“A preservation letter means I now have access to the data.”

No. Preservation and lawful retrieval are separate issues.

California authority map

Primary Law · Vehicle Code §20001 Injury/death crash — duty to stop

Requires the driver of a vehicle involved in an accident causing injury or death to stop immediately and perform the duties identified in §§20003 and 20004.

Primary Law · Vehicle Code §20002 Property-only crash duties

Requires immediate stopping at the nearest location that will not impede traffic or jeopardize motorists, specifies information duties and expressly provides that compliant vehicle movement does not affect fault.

Primary Law · Vehicle Code §20003 Information and reasonable assistance

Requires specified identifying information after an injury/death crash and reasonable assistance for injured persons, including arranging medical transportation where necessary or requested.

Primary Law · Vehicle Code §20004 Additional fatal-crash reporting duty

Requires specified reporting where a death results and no traffic or police officer is present to receive the required information.

Primary Law · Vehicle Code §20008 24-hour injury/death accident report

Requires the driver of a non-common-carrier vehicle involved in a qualifying injury or death accident to make or cause a written report to CHP or appropriate city police within 24 hours.

Primary Law · Vehicle Code §16000 DMV accident reporting

Generally requires reporting within 10 days when a motor-vehicle accident causes bodily injury, death, or more than $1,000 damage to the property of any one person, subject to statutory exceptions.

California DMV · SR-1 Report of Traffic Accident Occurring in California

DMV's current procedure confirms the 10-day filing rule for qualifying crashes and states that SR-1 reporting is required in addition to reports made to police, CHP or the driver's insurer.

Primary Law · Vehicle Code §20012 Access to accident-report information

Allows disclosure of required accident-report contents to specified persons having a proper interest, including involved drivers, injured persons, owners and qualifying representatives.

Primary Law · Vehicle Code §20013 Use of required accident reports at trial

Restricts use of specified accident reports as evidence in civil or criminal trials arising from the accident, subject to the statute's compliance-certificate exception.

California Highway Patrol Crash report request / CHP 190

CHP permits qualifying parties of interest to obtain CHP crash reports/investigations through its current crash-report portal or CHP 190 request procedure.

Primary Law · Vehicle Code §9951 Event data recorders

Requires manufacturer disclosure of qualifying EDR/SDM systems, identifies categories of recorded crash information and restricts retrieval without registered-owner consent or another statutory basis.

Primary Law · Evidence Code §669 Negligence per se

Creates a rebuttable presumption of failure to exercise due care when a statutory violation, causation, protected occurrence and protected class requirements are all established.

Primary Law · Evidence Code §413 Willful suppression of evidence

Allows the trier of fact, when drawing inferences from evidence, to consider a party's willful suppression of relevant evidence where established.

Source-control rule: reports summarize evidence. They are not substitutes for the evidence itself. Preserve original photographs, video, electronic data, physical evidence and witness accounts whenever possible and maintain a record of where each item came from.

Frequently asked questions

Should I move my car after a minor California crash?

If the crash resulted only in property damage, Vehicle Code §20002 requires stopping at the nearest location that will not impede traffic or jeopardize motorists. The statute expressly says compliant movement does not affect fault.

What if someone may be injured?

Injury crashes trigger different statutory duties under §§20001 and 20003. Address safety and medical needs and follow law-enforcement and emergency instructions.

Do I have to report a California injury crash within 24 hours?

Vehicle Code §20008 generally requires the driver of a non-common- carrier vehicle involved in an accident causing injury or death to make or cause a written report to CHP or the appropriate city police agency within 24 hours.

When do I have to file an SR-1?

The general California rule requires an SR-1 within 10 days where anyone is injured or killed or where damage to the property of any one person exceeds $1,000, subject to statutory exceptions.

Does the police report satisfy the SR-1 requirement?

No. California DMV expressly states that a qualifying SR-1 is required in addition to police, CHP or insurance-company reports.

Do I file an SR-1 only if I caused the accident?

No. DMV states that the qualifying report must be filed regardless of fault.

How do I obtain a CHP collision report?

A qualifying party of interest can currently request the report through CHP's Crash Portal or use the CHP 190 process.

Does the police officer decide legal fault?

The officer's investigation and conclusions are important evidence, but a civil case still requires analysis of admissible evidence, applicable duties, causation and California comparative-fault law.

What should I photograph?

Start wide: the entire scene and every approach. Then photograph vehicle positions, traffic controls, sight lines, impact damage, debris, marks, road conditions and identifying information.

What is an EDR?

An event data recorder is a manufacturer-installed recording system that can preserve specified crash-related information. Vehicle Code §9951 governs certain California EDR disclosure and retrieval issues.

Can anyone download a vehicle's EDR?

No. Section 9951 generally restricts retrieval by someone other than the registered owner unless owner consent, a court order or another statutory exception applies.

Should a wrecked car be salvaged immediately?

Not when vehicle condition, EDR information, mechanical failure, crash reconstruction or injury mechanics may be disputed. Resolve preservation and inspection needs before irreversible disposition.

Can surveillance video disappear?

Yes. Many private and governmental video systems use short routine retention cycles. Identify and request preservation promptly.

Does a traffic-law violation automatically prove negligence?

No. Evidence Code §669 imposes additional requirements involving causation, the type of occurrence and the class the law was intended to protect.

Why investigate insurance while investigating the crash?

The same facts often control both. Ownership, employment, business use, permission, rideshare status and commercial operation can determine who is liable and which policies respond.

What is the best overall crash-investigation method?

Preserve facts first. Build the timeline. Identify applicable legal duties. Determine breach and causation. Then address comparative fault, damages and insurance.

← Guide 17 Comparative Fault California Library Return to the California state landing page.

Next: Guide 19 Crash Damages

The investigation should produce the fault analysis—not begin with one.

Protect people first. Preserve the scene. Identify witnesses. Secure disappearing video and electronic evidence. Preserve the vehicles. Obtain the complete police investigation. Build a master chronology. Find every potentially applicable policy. Then move from facts to legal duties, from duties to breach, from breach to causation, and only then to comparative fault and damages.

Public legal education only. VictimsGuide.com does not provide individualized legal advice and does not create an attorney-client relationship. Crash investigation can involve safety concerns, privacy rights, electronic-data restrictions, evidentiary rules, expert analysis, preservation obligations and strict reporting or claim deadlines. Verify the current statutes, applicable agency procedures and facts of the particular collision before legal reliance.