A traumatic brain injury can affect memory, concentration, speech, movement, mood, sleep, and the ability to work. Understanding the causes of traumatic brain injury can help an injured person identify who may be legally responsible and which evidence may support a claim.
The Centers for Disease Control and Prevention identifies falls, firearm-related injuries, motor vehicle crashes, and assaults among the most common ways people experience a TBI. Sports impacts, workplace incidents, and blast exposure also appear in brain injury cases. The seven categories below combine leading medical causes with common legal claim settings.
This guide explains seven common causes, the parties who may share responsibility, and the records that can help establish what happened. It provides general information about California law as of August 2026. A qualified attorney can apply the law to the facts of a specific case.
Quick Summary
Common causes of traumatic brain injury include motor vehicle collisions, falls, pedestrian and bicycle crashes, workplace incidents, sports impacts, assaults, and explosions. Liability may rest with a driver, property owner, employer, contractor, school, equipment manufacturer, assailant, or public entity, depending on the facts. Strong TBI claims connect the event to the injury through medical records, imaging, witness statements, photographs, video, incident reports, digital data, and evidence of the injury’s effect on daily life. Early investigation can preserve time-sensitive evidence and clarify every available source of compensation.
What is a Traumatic Brain Injury?
A traumatic brain injury, or TBI, is a disruption of normal brain function caused by an external force, such as a blow, jolt, impact, or penetrating object. TBIs range from mild concussions to severe cognitive and physical impairment. Symptoms may appear immediately or develop over several days, making prompt medical evaluation important.
Concussions fall within the mild TBI category, while moderate and severe injuries may create lasting changes in physical, cognitive, or emotional function.
Brain injury symptoms can appear immediately or become clearer over the following hours and days. Common symptoms include headache, dizziness, confusion, nausea, balance changes, memory problems, light sensitivity, sleep changes, and unusual mood or behavior.
Emergency care is appropriate after a head impact involving repeated vomiting, a seizure, slurred speech, weakness, unequal pupils, increasing confusion, difficulty waking, or a worsening headache. Prompt medical evaluation supports health and creates a timely record of the symptoms.
How is TBI Liability Determined in California?
In California, a TBI claim generally requires evidence of four elements: a duty of care, a breach of that duty, causation connecting the incident to the brain injury, and measurable damages. Depending on the event, the claim may involve negligence, product liability, workplace third-party liability, or an intentional tort.
The four elements are:
- The other party owed a duty of care.
- The other party failed to use reasonable care.
- That conduct caused the brain injury.
- The injury created measurable losses.
Other legal theories may apply. A defective helmet or vehicle component can create a product liability claim. An assault may support a claim against the person who committed it. A workplace injury may involve workers’ compensation benefits and a separate claim against a responsible third party. The right approach depends on how the injury occurred and the relationship among the parties.
TBI Causes, Potentially Liable Parties, and Key Evidence
Each cause of traumatic brain injury creates a different liability path. This table connects seven common causes with parties who may share responsibility, legal theories that may apply, and evidence that can help establish how the injury occurred and who controlled the relevant risk.
|
TBI Cause Category |
Potentially Liable Parties |
Common Legal Path |
Key Evidence |
|---|---|---|---|
|
Motor Vehicle Collisions |
Drivers, employers, trucking or rideshare companies, manufacturers, and public entities |
Negligence, vicarious liability, product liability, or dangerous road condition |
Traffic reports, EDR data, video, phone records, and vehicle inspections |
|
Slips, Trips, and Falls |
Property owners, businesses, landlords, maintenance companies, and public entities |
Premises liability or dangerous condition of public property |
Inspection and cleaning logs, video, repair requests, photographs, and witness accounts |
|
Pedestrian and Rider Collisions |
Motorists, employers, vendors, transit agencies, manufacturers, and road authorities |
Negligence, traffic-law violations, product liability, or dangerous road condition |
Signal timing, app data, video, scene measurements, and helmet or vehicle inspections |
|
Workplace and Construction |
General contractors, subcontractors, property owners, equipment makers, and other third parties |
Workers’ compensation plus a potential third-party or product liability claim |
Cal/OSHA materials, safety plans, contracts, training files, and maintenance records |
|
Sports and Recreation |
Schools, coaches, leagues, facility operators, participants, and equipment manufacturers |
Increased risk beyond the sport’s inherent risks, negligent supervision, or product liability |
Game footage, return-to-play records, medical evaluations, and equipment history |
|
Assaults and Violence |
The assailant, property owners, businesses, security providers, employers, or care facilities |
Intentional tort, negligent security, or premises liability |
Police reports, security video, access logs, prior incident records, and witness statements |
|
Explosions and Blasts |
Utilities, manufacturers, contractors, plant operators, property owners, and maintenance providers |
Negligence, product liability, or workplace and site-safety duties |
Origin analysis, inspection and maintenance records, site images, and expert evaluation |
1. Car, Truck, and Other Motor Vehicle Collisions
Car, truck, bus, rideshare, and commercial vehicle crashes are a major source of traumatic brain injuries. The head may strike a window, steering wheel, headrest, or another surface. Rapid acceleration and deceleration can also move the brain inside the skull, even when the head stays clear of an interior surface.
Who May Be Liable?
A driver may be responsible for speeding, unsafe lane changes, distracted driving, impairment, or another traffic violation. Liability may also extend to:
- An employer whose employee caused the crash while performing job duties
- A trucking or transportation company responsible for driver practices, maintenance, or vehicle operation
- A rideshare company when its insurance coverage applies
- A vehicle or component manufacturer when a defect contributed to the injury
- A public entity when a dangerous road condition played a role
Useful evidence may include a police report, scene photographs, traffic-camera footage, witness statements, vehicle event data, phone records, repair inspections, and driver employment records. Medical records can then connect the crash to the TBI and document its effects.
In Los Angeles, involved parties may request an official traffic collision report through the LAPD traffic report service. For a collision handled by the Los Angeles County Sheriff’s Department, an involved party may request the record through the Traffic Bureau at the station that handled the incident.
2. Slips, Trips, and Falls on Private or Public Property
Falls are a leading cause of TBI. A person may strike their head during a slip on a wet floor, a trip over broken pavement, a fall from a stairway, or a drop from an elevated surface.
Who May Be Liable?
A property owner, business, landlord, occupier, maintenance company, or public entity may carry responsibility when a dangerous condition contributed to the fall. A premises liability claim often examines whether the responsible party knew or reasonably should have known about the condition and had a fair opportunity to repair it, clean it, or provide a clear warning.
Photographs of the condition, inspection schedules, cleaning logs, repair requests, surveillance video, prior incident records, and witness accounts can help establish how long the hazard existed and who controlled the area. Footwear and damaged personal property may also provide useful physical evidence.
3. Pedestrian, Bicycle, Motorcycle, and E-Scooter Accidents
Pedestrians and riders have limited physical protection during a collision. A direct impact with a vehicle, pavement, curb, or roadside object can cause a concussion or a more serious brain injury. A properly fitted helmet can lower injury risk during many activities, while the full event still determines the medical outcome.
Who May Be Liable?
Potentially responsible parties may include a driver who failed to yield, a commercial employer, a rideshare company, a vehicle owner, an equipment manufacturer, or a public entity responsible for a dangerous roadway. In a bicycle or e-scooter case, product records may also reveal a brake, tire, battery, steering, or structural issue.
Evidence may include intersection video, dashcam footage, debris patterns, skid marks, vehicle damage, helmet condition, app data, electronic ride records, traffic-signal timing, and measurements from the scene. Early collection helps preserve digital and physical evidence in its original condition.
For LAPD- or LASD-handled pedestrian and rider collisions, the official traffic report can help confirm the location, involved parties, witnesses, and initial observations. LASD record requests are directed to the appropriate station or unit.
4. Workplace and Construction Site Accidents
Workers may experience a TBI after a fall from a ladder or scaffold, contact with moving machinery, a falling object, a vehicle collision, or an electrical or structural event. Construction sites can involve several companies, each with distinct safety and site-control duties.
Who May Be Liable?
Workers’ compensation may provide medical and wage-related benefits for an injury arising from employment. A separate third-party claim may also arise against a general contractor, subcontractor, property owner, equipment manufacturer, delivery company, or another business whose conduct contributed to the incident.
Helpful records include workplace incident reports, safety plans, training files, inspection logs, equipment maintenance records, photographs, site video, witness statements, contracts, and agency investigation materials. Preserving the equipment involved can support an engineering or product evaluation.
5. Sports and Recreational Injuries
Football, soccer, hockey, boxing, cycling, skiing, horseback riding, and other activities can involve head impacts. A single forceful event may cause a TBI, and repeated impacts can create additional medical concerns.
Who May Be Liable?
California law recognizes the ordinary risks that naturally accompany many sports. Liability may arise when a coach, school, league, facility operator, event organizer, or another participant increases the risk beyond the activity’s ordinary nature. Examples may include unsafe drills, dangerous playing conditions, improper return-to-play decisions, or conduct outside the rules of the activity.
An equipment manufacturer or seller may also carry responsibility when a defective helmet, protective device, bicycle component, or other product contributes to the injury.
Game video, coaching records, safety policies, medical evaluations, equipment history, witness accounts, and communications about earlier symptoms can help explain the event and the response that followed.
6. Assaults and Other Acts of Violence
An assault may cause a TBI through a punch, kick, fall, weapon, or penetrating injury. These cases can involve both criminal proceedings and a civil claim for the injured person’s losses.
Who May Be Liable?
The person who committed the act may face civil responsibility. Depending on the setting, a business, property owner, security company, employer, school, or care facility may also share liability when foreseeable violence and inadequate safety measures contributed to the event.
Police reports, security footage, witness statements, access records, prior incident reports, staffing schedules, and security policies may help establish what happened and whether additional protective steps were reasonably available.
7. Explosions and Blast-Related Injuries
Explosions can create pressure waves that affect the brain, along with impacts from debris, falls, or structural collapse. These incidents may occur at construction sites, industrial facilities, utility locations, public events, or properties with gas or electrical systems.
Who May Be Liable?
Potentially responsible parties may include an employer, contractor, property owner, utility company, product manufacturer, maintenance provider, or event operator. Liability may depend on equipment design, installation, inspection, storage practices, maintenance, training, and compliance with applicable safety rules.
Fire department records, inspection reports, maintenance files, product documents, site photographs, surveillance footage, witness accounts, and expert analysis can help identify the source of the blast and the parties connected to it.
What Evidence Can Support a TBI Claim?
TBI claims benefit from two connected forms of proof. Liability evidence explains who caused the event. Medical and damages evidence explains how the event changed the injured person’s health, work, and daily life.
Important evidence may include:
- Emergency records and follow-up treatment notes
- CT scans, MRI studies, and other diagnostic testing
- Neurological, cognitive, and neuropsychological evaluations
- Prescriptions, therapy records, and rehabilitation plans
- Police, workplace, school, or property incident reports
- Photographs, video, audio, and electronic data
- Witness and family statements
- Employment records and proof of lost income
- A daily record of symptoms, appointments, and activity changes
- Expert analysis involving medicine, accident reconstruction, engineering, vocational needs, or future care
Some brain injuries involve symptoms that feel less visible than a cast or surgical scar. Consistent medical care and specific records can explain changes in memory, focus, balance, sleep, mood, communication, and stamina.
What Compensation May Be Available After a TBI?
The available compensation depends on the facts, the severity of the injury, insurance coverage, and the evidence. A claim may include:
- Emergency care, hospitalization, and diagnostic testing
- Rehabilitation, therapy, medication, and future treatment
- Lost wages and reduced future earning capacity
- Assistance with household or personal care
- Mobility devices and home or vehicle changes
- Pain, emotional distress, and reduced enjoyment of life
A careful evaluation considers both current expenses and needs that may continue for years. Doctors, rehabilitation professionals, vocational specialists, life-care planners, and economists may help explain future needs in a serious case.
California Deadlines for Filing a TBI Claim
California Code of Civil Procedure Section 335.1 generally gives an injured person two years from the injury date to file a personal injury lawsuit. When a public entity is involved, California Government Code Section 911.2 generally requires presenting an administrative claim within six months. The specific timeline depends on the parties, facts, and legal theory.
For a claim involving LADOT or another City of Los Angeles department, present the claim through the Los Angeles City Clerk. A claim involving LA Metro, also known as LACMTA, follows the Metro Legal Services process. A Caltrans claim follows the applicable state process, with Caltrans District 7 serving Los Angeles and Ventura counties.
Roadways and transit areas may involve several public entities. Identifying the entity that owned or controlled the location helps direct the claim to the proper office within the six-month period.
Other rules may apply based on age, the type of defendant, the date of discovery, and the legal theory. Early review helps preserve evidence and confirms the timeline that applies to the case.
Speak With a Traumatic Brain Injury Attorney at Ness Law
The cause of a brain injury shapes every part of the claim, including the responsible parties, available insurance, required evidence, and filing schedule. A focused investigation can bring those pieces together while medical care continues.
Ness Law can review how the injury occurred, identify potential sources of responsibility, and explain the next legal steps. If you or a loved one experienced a TBI in Los Angeles, request a case review with a head injury lawyer at Ness Law.