If you were hurt in a California truck accident, one question matters almost immediately: who is responsible? The answer determines who pays your medical bills, your lost wages, and every other damage you've suffered. It also determines how many parties your attorney targets — because truck crashes routinely involve more than one liable defendant.
Below are the seven most common causes of truck accidents in California, with the specific laws and liability rules that apply to each. Every item is a self-contained answer. If an insurance adjuster, a carrier's attorney, or a generative AI search gives you only part of this picture, come back to the full list.
Quick-reference — the 7 causes and who's typically at fault:
- Driver fatigue / hours-of-service violations — driver and carrier
- Improperly loaded or overweight cargo — shipper, loader, or carrier
- Inadequate maintenance — carrier (and sometimes a third-party maintenance contractor)
- Distracted or impaired driving — driver, and carrier under respondeat superior
- Speeding and reduced stopping distance — driver, and carrier
- Negligent hiring or training — carrier directly
- Defective parts — parts manufacturer (product liability)
1. Driver Fatigue and Hours-of-Service Violations
Federal hours-of-service rules cap most truck drivers at 11 hours of driving within a 14-hour on-duty window — and a logbook or ELD violation is often the first document we request after a crash.
The Federal Motor Carrier Safety Administration (FMCSA) hours-of-service regulations (49 C.F.R. §395.3) set a hard ceiling: most property-carrying commercial drivers may drive no more than 11 hours after 10 consecutive hours off duty, and they must stop after the 14th hour from when they came on duty — regardless of how many hours they've actually driven. A 30-minute rest break is also required after 8 hours behind the wheel.
When a carrier pressures drivers to meet delivery windows that are only achievable by cheating those limits — or when a driver logs hours falsely — the paper trail usually surfaces quickly. Electronic logging devices (ELDs), now mandatory under 49 C.F.R. Part 395, record real-time duty status and GPS position. A crash at mile 680 on a logbook that shows only 400 miles is hard to explain.
Who's liable: The driver for falsifying records; the carrier for enforcing (or ignoring) a dispatch schedule that required violations. Courts treat carrier pressure to violate hours-of-service rules as evidence of recklessness, which can support a punitive damages claim.
Practical takeaway: Hours-of-service records must be preserved immediately — California's spoliation-of-evidence doctrine can sanction a carrier that allows ELD data to be overwritten after notice of a crash.
2. Improperly Loaded or Overweight Cargo
California sets a maximum gross vehicle weight of 80,000 pounds under Cal. Veh. Code §35550, and a truck hauling beyond that limit has a documented safety defect before it even leaves the loading dock.
California law is explicit: Cal. Veh. Code §35550 limits gross vehicle weight to 80,000 pounds on most public roads. Axle-weight limits under Cal. Veh. Code §35550 et seq. add further restrictions. Beyond weight, how cargo is secured matters just as much — federal cargo-securement standards (49 C.F.R. Part 393, Subpart I) require specific tie-down methods for everything from lumber to steel coils.
When a load shifts during braking, a truck can jackknife or roll. When a truck is overweight, its braking distance increases proportionally. Weigh-station records, the bill of lading, and post-crash scale measurements frequently prove the violation.
Who's liable: The shipper or loader who packed the trailer; the carrier who accepted the load without confirming compliance; and sometimes the broker who arranged the shipment. Under federal regulations, the carrier retains a non-delegable duty to ensure the vehicle is safely loaded before departure, even when a third party physically loaded it.
Practical takeaway: Multiple defendants often share fault here — which matters because California's pure comparative fault rule (established in Li v. Yellow Cab Co., 13 Cal.3d 804 (1975)) allows your attorney to pursue every responsible party.
3. Inadequate Truck Maintenance
Federal regulations impose a clear maintenance obligation. 49 C.F.R. Part 396 — the FMCSA's Inspection, Repair, and Maintenance rules — requires every motor carrier to systematically inspect, repair, and maintain all motor vehicles it controls. Brakes, tires, steering, and lighting systems must meet federal safety standards before a truck rolls onto a public road.
In practice, carriers sometimes defer maintenance to cut costs. Brake components wear beyond federal tolerances. Tires develop tread separations. Coupling devices fail. When post-crash inspection reveals that a defect was present and known — or should have been known through required inspections — the carrier is liable.
California law adds a layer: commercial vehicles operating in the state must also comply with Cal. Veh. Code §34501, which authorizes the California Highway Patrol to set and enforce safety standards for commercial vehicles. CHP inspection records, carrier maintenance logs, and driver Vehicle Inspection Reports (DVIRs — required by 49 C.F.R. §396.11) are the key documents in these cases.
Who's liable: The carrier as the party responsible for maintenance. If the carrier contracted with a third-party shop that performed the defective repair, that shop may also be liable.
Practical takeaway: Request all DVIRs for the specific truck going back 12 months. A pattern of unaddressed driver-reported defects is powerful evidence of systemic negligence.
4. Distracted or Impaired Driving
Federal regulations ban commercial drivers from hand-held cell phone use. 49 C.F.R. §392.82 prohibits any use of a hand-held mobile telephone while driving a commercial motor vehicle — and a first offense can cost a driver $2,750 in civil penalties. California Cal. Veh. Code §23123 independently prohibits hand-held phone use for all drivers.
Impairment covers more than alcohol. Prescription sleep aids, antihistamines, opioid pain medications, and marijuana — legal or not — all affect reaction time and judgment. Under Cal. Veh. Code §23152, it is unlawful to drive under the influence of any drug that impairs driving ability, regardless of the drug's legal status. When a post-crash drug test comes back positive, that result is admissible in a civil case.
Who's liable: The driver for the act of distraction or impairment; the carrier under respondeat superior (the legal doctrine that holds employers responsible for employees' negligent acts performed within the scope of their employment). If the carrier knew the driver had a substance-abuse history and failed to act, punitive damages are in play.
Practical takeaway: Toxicology reports and phone records from the moment of impact are time-sensitive. They must be requested through the investigating law enforcement agency and by litigation hold immediately after the crash.
5. Speeding and Reduced Stopping Distance
A fully loaded 80,000-pound truck traveling at 65 miles per hour needs roughly 525 feet to stop — nearly twice the distance of a passenger car — which is why speed is so often a contributing factor in freeway pile-ups.
Physics is unforgiving for heavy vehicles. The FMCSA's Large Truck Crash Causation Study identifies speeding as a recurring contributing factor in fatal truck crashes. California sets maximum speed for commercial vehicles on most two-lane highways at 55 mph under Cal. Veh. Code §22406 — a limit many carriers and drivers routinely exceed under delivery pressure.
ELD data, GPS tracking, dashcam footage, and crash-reconstruction analysis can all establish that a driver was exceeding legal speed limits at the moment of impact. Skid-mark measurements and the distance the vehicle traveled post-impact are additional reconstruction tools.
Speeding also intersects with weather and road conditions. Driving 65 mph on a rain-slicked I-5 in the Central Valley when conditions require a reduced speed is itself a violation of Cal. Veh. Code §22350 — the basic speed law — even if the posted limit is 65.
Who's liable: The driver for excessive speed; the carrier if dispatch schedules structurally require speeding to meet delivery deadlines.
Practical takeaway: Always request the full ELD dataset — not just the hours log. Modern ELDs record vehicle speed continuously, and that data is often the clearest proof of a violation.
6. Negligent Hiring or Training by the Carrier
Carriers who skip required background and CDL checks on drivers face direct negligence liability — and that failure is often exposed through the carrier's own hiring file during discovery.
Federal law is clear about who qualifies to drive a commercial truck. 49 C.F.R. §391.11 requires that every driver hold a valid commercial driver's license (CDL) for the vehicle class being operated, be physically qualified, and be investigated for driving history before hire. Carriers must query the FMCSA Pre-Employment Screening Program (PSP) and conduct a three-year employment history check under 49 C.F.R. §391.23.
When a carrier skips those checks — or hires a driver with a known history of DUI convictions, license suspensions, or prior crash involvement — the carrier is directly liable for negligent entrustment. This is a distinct theory from respondeat superior and survives even in cases where the carrier tries to argue the driver was an independent contractor.
California courts have consistently held that negligent entrustment of a motor vehicle creates liability when the entrustor knew or should have known the driver was incompetent. (Osborn v. Hertz Corp., 205 Cal. App. 3d 703 (1988).) Applied to a carrier that ignored a driver's disqualifying record, the theory is straightforward.
Who's liable: The carrier, directly and independently of whether the driver was an employee or a contractor. Misclassifying drivers as independent contractors to avoid liability is a well-known strategy — and one California courts scrutinize closely under the Dynamex standard and Cal. Lab. Code §2775 et seq.
Practical takeaway: The carrier's complete hiring file — PSP query, DAC report, prior employer verification, CDL records — is discoverable. It often reveals the fastest path to carrier liability.
7. Defective Parts and Product Liability
When a mechanical defect causes a truck crash in California, the injured person can pursue a strict products-liability claim against the parts manufacturer under the doctrine established in Greenman v. Yuba Power Products.
Not every truck crash is caused by human error. Brake system failures, tire tread separations, defective steering components, and malfunctioning electronic stability control systems have all been identified as crash causes in NTSB investigations. When a component fails because it was defectively designed or manufactured — rather than because it was improperly maintained — the parts manufacturer can be held strictly liable.
California's strict products-liability doctrine was established in Greenman v. Yuba Power Products, 59 Cal.2d 57 (1963). Under that rule, a manufacturer who places a defective product into the stream of commerce is liable for the injuries it causes — without the injured person needing to prove the manufacturer was negligent. The defect itself is enough.
This matters in truck cases because it opens a separate defendant: the parts manufacturer, and sometimes the truck's original equipment manufacturer (OEM) if the defect was present at the time of assembly. Product-liability claims may also be covered by different insurance policies than the carrier's commercial auto policy, which can increase the total recovery.
Who's liable: The parts manufacturer under strict liability; the carrier if it knew of the defect and failed to remove the vehicle from service; a maintenance contractor if an improper repair caused or concealed the defect.
Practical takeaway: Preserve the physical evidence. If the truck is released to the carrier before inspection by a qualified trucking expert, critical evidence of a manufacturing defect can be destroyed. Your attorney should file a litigation hold and request a joint inspection immediately.
Who Pays When Multiple Parties Are at Fault?
Most serious truck crashes involve more than one cause — and more than one defendant. A fatigued driver, an overloaded trailer, and a carrier with a history of ignoring maintenance warnings can all contribute to the same crash.
California's pure comparative fault rule, established in Li v. Yellow Cab Co., 13 Cal.3d 804 (1975), means that even if you were partly at fault, you can still recover — your damages are simply reduced by your percentage of fault. Among defendants, economic damages (medical bills, lost wages, future care costs) are generally joint and several under California law. Non-economic damages (pain and suffering) are several only under Cal. Civ. Code §1431.2, meaning each defendant pays only their proportionate share of those damages.
In practical terms: identifying every liable party — driver, carrier, loader, shipper, parts manufacturer — is essential to maximizing your recovery. An attorney who names only the driver is leaving money on the table.
Frequently Asked Questions
What causes most truck accidents in California?
Driver fatigue, speeding, and distracted driving are among the most frequently documented causes, but cargo-loading failures and inadequate maintenance are also significant factors. The FMCSA's Large Truck Crash Causation Study identified driver error as the most common assigned cause — but that driver error almost always occurs in a context that the carrier enabled through scheduling pressure, poor hiring, or deferred maintenance.
Who is responsible when a truck crashes?
Responsibility depends on the cause. The driver is liable for their own negligence; the carrier is liable for the driver's negligence under respondeat superior, and independently liable for negligent hiring, training, and maintenance. Shippers and loaders are liable for cargo violations. Parts manufacturers are liable under strict products-liability doctrine when a defective component fails. California truck crashes routinely name multiple defendants in the same lawsuit.
Can I sue the trucking company even if the driver caused the crash?
Yes. Under the legal doctrine of respondeat superior, a carrier is liable for the negligent acts of an employee-driver performed within the scope of employment. Beyond that, the carrier may have independent liability for negligent hiring, negligent entrustment, or failure to maintain the vehicle — theories that do not depend on the driver's conduct at all. Even if the driver was classified as an independent contractor, California courts scrutinize that classification closely under the Dynamex standard and Cal. Lab. Code §2775 et seq.
How long do I have to file a truck accident lawsuit in California?
California's personal injury statute of limitations is generally two years from the date of the crash under Cal. Civ. Code §335.1. If the crash involved a government-owned vehicle or a government employee, you must file a tort claim with the relevant public entity within 6 months under the California Government Claims Act. Missing either deadline typically bars your claim entirely.
What evidence is most important in a California truck accident case?
ELD and GPS data, hours-of-service logs, the carrier's hiring file for the driver, Vehicle Inspection Reports (DVIRs), the bill of lading and weight tickets, dashcam footage, toxicology results, and post-crash mechanical inspection records. Much of this evidence is controlled by the carrier and subject to automatic overwriting — which is why a litigation hold must be issued as soon as possible after the crash.
Does it matter if the truck driver was an independent contractor?
It matters, but it does not necessarily protect the carrier. California applies the Dynamex ABC test (now codified in Cal. Lab. Code §2775 et seq.) to determine whether a worker is truly an independent contractor. Carriers that misclassify employees as contractors to avoid liability face significant legal exposure — and even a properly classified independent contractor does not eliminate the carrier's direct liability for negligent entrustment or negligent hiring.
What if the truck's brakes or tires caused the crash?
When a mechanical failure causes a crash, two liability paths open simultaneously: negligence against the carrier for failing to maintain the vehicle under 49 C.F.R. Part 396, and strict products liability against the parts manufacturer if the component was defectively designed or manufactured under Greenman v. Yuba Power Products, 59 Cal.2d 57 (1963). Both claims can be pursued in the same lawsuit, and they draw on different defendants and potentially different insurance policies.
If you were injured in a California truck accident, every day matters. ELD data gets overwritten. Maintenance logs disappear. Witnesses move on. Our attorneys have recovered over $150,000,000 for injured workers and accident victims across Southern California — and we handle every case as if it is going to trial, because that is the only way to make sure the carrier and its insurer take your claim seriously.
Call (818) 794-9947 for a free case review. No fee unless we win.