Truck Accident Liability in San Diego: Who's Responsible?

The truck driver who caused a crash may be only one of several responsible parties. Commercial trucking spreads responsibility among drivers, motor carriers, owner-operators, freight brokers, shippers, cargo loaders, maintenance companies, and equipment manufacturers.

When a serious truck accident occurs, identifying every person and company that contributed to it can be critical to proving what happened and determining what insurance coverage is available.

Depending on the facts, responsibility may extend to:

• the truck driver;
• the motor carrier;
• an owner-operator or equipment owner;
• a freight broker;
• a shipper or cargo loading company;
• a maintenance or repair contractor;
• the manufacturer of a defective truck or component; or
• a government entity responsible for a dangerous roadway.

Our San Diego truck accident attorneys investigate these relationships early because important evidence is often held by several different companies. This guide explains the major sources of truck accident liability under California and federal law.

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Why Truck Accidents Can Have Multiple Responsible Parties

Commercial trucking is different from an ordinary two-car accident because the driver, tractor, trailer, cargo, and shipment may all be controlled by different businesses.

A motor carrier may operate the truck while leasing the tractor from an owner-operator. Another company may own the trailer. A freight broker may have selected the carrier. A shipper or warehouse may have loaded the cargo. An outside repair facility may have serviced the brakes or tires.

Each company has its own role, records, employees, contracts, and potentially its own insurance coverage.

That structure is particularly important in serious crashes involving traumatic brain injuries, spinal injuries, amputations, burns, or wrongful death. Our guide to common truck accident injuries in San Diego explains why collisions involving large commercial vehicles can cause catastrophic harm.

Identifying every legally responsible party may also uncover additional insurance coverage. Our guide to insurance coverage for truck accidents explains how multiple policies and layers of coverage can apply.

Freight traveling through San Diego frequently moves along Interstate 5, Interstate 8, Interstate 15, and the border transportation network around Otay Mesa. A collision may occur here even though the companies involved in the shipment are headquartered elsewhere in California or across the country.

Different collision patterns can also point toward different forms of negligence. Our overview of the types of truck accidents in San Diego explains common crashes such as jackknifes, rollovers, underride collisions, and lost-load accidents.

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The Truck Driver

The truck driver is usually the starting point of the liability investigation.

California negligence law requires drivers to use reasonable care. Under CACI No. 400, an injured person generally must prove that the defendant was negligent, that the plaintiff was harmed, and that the negligence was a substantial factor in causing the harm.

Examples of truck driver negligence include:

• speeding or driving too fast for conditions;
• following too closely;
• unsafe lane changes;
• distracted driving;
• driving while impaired;
• failing to inspect the truck or cargo when required;
• continuing to drive while dangerously fatigued; and
• violating federal hours-of-service or other safety requirements.

A violation of a safety statute or regulation may also create a presumption of negligence under California Evidence Code section 669 when the requirements of negligence per se are satisfied. CACI No. 418 explains how the doctrine applies.

Federal trucking rules can therefore become important evidence in a California truck accident case. Hours-of-service requirements, vehicle inspection regulations, cargo rules, and other safety standards may help establish what the driver was required to do. Our guide to FMCSA regulations in truck accident lawsuits explains how these federal standards can affect a civil case.

A regulatory violation, however, must still be connected to the crash and the injuries it caused.

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The Motor Carrier

The motor carrier is often the central corporate defendant in a truck accident case.

A carrier may be responsible for the driver's negligence, its own negligent conduct, or both, depending on the relationship between the parties and the circumstances of the crash.

Respondeat Superior: Liability for Employee Drivers

When a truck driver is an employee acting within the scope of employment, the employer can be vicariously liable for the driver's negligence.

This is the doctrine of respondeat superior. The injured person generally does not need to prove that the employer personally drove carelessly. Instead, the company can be held responsible because its employee committed the negligent act while acting within the scope of employment.

CACI No. 3701 addresses this form of employer liability.

Owner-Operators and Leased Trucks

Trucking companies frequently use owner-operators rather than company-owned tractors and employee drivers.

The contracts governing these arrangements matter, but the label placed on the relationship is not necessarily the end of the analysis.

Under the federal motor-carrier leasing regulations in 49 C.F.R. Part 376, an authorized carrier leasing equipment generally must have exclusive possession, control, and use of the equipment for the duration of the lease and assume responsibility for its operation.

The regulation does not, however, automatically determine whether the driver is an employee or independent contractor for every purpose.

The actual relationship, operating authority, lease documents, dispatch records, control over the shipment, and applicable state and federal law must all be examined.

The Carrier's Own Negligence

A motor carrier may also have created or increased the danger through its own conduct.

Examples include:

• Negligent hiring or retention. Hiring or continuing to employ a driver despite information showing the driver was unsafe or unqualified.
• Negligent training or supervision. Failing to properly train or monitor drivers.
• Negligent entrustment. Allowing an unfit driver to operate commercial equipment.
• Unsafe dispatch practices. Creating schedules or delivery expectations that encourage speeding, fatigue, or hours-of-service violations.
• Negligent maintenance. Allowing unsafe tractors or trailers to remain in service.

California law contains an important limitation on some of these theories.

In Diaz v. Carcamo, the California Supreme Court held that when an employer admits vicarious liability for an employee's negligent driving within the scope of employment, separate negligent entrustment, hiring, or retention theories based on that same driving generally should not be separately submitted to the jury.

That does not mean the carrier's conduct is always irrelevant. The pleadings, admissions, theories of liability, and evidence must be analyzed in the context of the particular case. Our discussion of Diaz v. Carcamo and vicarious liability explains the issue in more detail.

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Freight Brokers

A freight broker arranges transportation by connecting a shipper with a motor carrier. The broker generally does not operate the truck itself.

A broker can nevertheless become important when there is evidence that it selected a carrier that was unsafe or unqualified.

This area of law changed significantly in 2026.

In Montgomery v. Caribe Transport II, LLC, decided May 14, 2026, the United States Supreme Court considered whether the Federal Aviation Administration Authorization Act preempted a state-law negligent-selection claim against a freight broker.

The Court held that the claim fell within the statute's safety exception. As a result, the FAAAA does not provide freight brokers with categorical immunity from negligent-selection claims involving motor-carrier safety.

That does not make a broker automatically responsible whenever a carrier causes a crash. The plaintiff must still establish the elements of the applicable negligence claim.

But broker selection can be an important part of the investigation when the carrier had significant safety problems that were known or reasonably discoverable before the shipment was assigned.

Carrier safety history, federal inspection data, out-of-service rates, contracts, communications, and the broker's internal carrier-selection records can all become important evidence.

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Shippers and Cargo Loading Companies

The company whose goods were being transported is not automatically responsible for the negligence of an independent motor carrier.

A shipper or separate loading company may nevertheless bear responsibility when its own conduct contributed to the crash.

Examples include:

• improperly distributing the weight of the cargo;
• overloading the vehicle or an individual axle;
• failing to properly secure freight;
• concealing a loading defect that could not reasonably be discovered by the driver;
• failing to disclose dangerous characteristics of the cargo; or
• exercising sufficient control over transportation operations to create an independent basis for liability.

Federal cargo-securement standards are part of the federal motor carrier safety regulations. They require cargo to be contained, immobilized, or secured so it does not fall from the vehicle or shift enough to adversely affect the truck's stability or maneuverability.

Drivers and carriers also have their own responsibilities for inspecting cargo and ensuring that loads are properly distributed and secured.

For that reason, cargo cases often require investigation of both the company that loaded the trailer and the driver or carrier that accepted and transported it.

Bills of lading, photographs, loading diagrams, weight tickets, seal records, warehouse video, and electronic records can help establish who controlled the loading process and what went wrong.

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Maintenance and Repair Contractors

A tractor-trailer depends on brakes, tires, steering, suspension, coupling equipment, lighting, and many other components working properly under heavy loads.

Federal regulations require motor carriers to systematically inspect, repair, and maintain commercial vehicles under their control.

Many carriers outsource some or all of this work.

If a repair shop negligently services the brakes, installs a tire incorrectly, overlooks a dangerous defect, or certifies equipment as safe when it is not, the maintenance contractor may share responsibility for a resulting crash.

Outsourcing maintenance does not necessarily remove the carrier from the case. Motor carriers retain important federal responsibilities for ensuring that equipment under their control is properly inspected, repaired, and maintained.

Roadside inspections can also provide valuable evidence. An earlier out-of-service violation or documented mechanical defect may show that a dangerous condition existed before the crash.

Important evidence can include maintenance histories, work orders, invoices, roadside inspection reports, driver defect reports, annual inspection records, technician notes, and the physical components themselves.

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Manufacturers of Defective Trucks or Parts

Sometimes a truck accident is caused or made substantially worse by a defective product.

Potential defects include:

• defective tires;
• brake components;
• steering systems;
• trailer couplings;
• fuel systems;
• electronic safety systems;
• structural components; or
• underride protection.

California product liability law can impose strict liability when a defective product causes injury.

Unlike an ordinary negligence claim, strict liability does not necessarily require proof that the manufacturer acted carelessly. The focus is instead on whether the product was defective, whether the defendant was legally responsible for placing it into the stream of commerce, and whether the defect was a substantial factor in causing the injury.

CACI No. 1200 provides the general framework for strict product liability in California.

Product cases often require engineers and other technical experts. Preserving the truck, trailer, failed component, electronic data, and other physical evidence can be critical.

Our San Diego auto defect attorneys handle product-liability investigations alongside truck accident claims when defective vehicles or components may have contributed to a crash.

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Government Entities and Dangerous Roads

Not every truck crash is caused solely by a driver or trucking company.

Roadway design or maintenance can contribute to a collision involving a large commercial vehicle. Potential dangerous conditions can include inadequate sight distance, unsafe merge configurations, defective traffic controls, missing or misleading warnings, dangerous construction zones, or other physical roadway conditions.

California Government Code section 835 establishes the framework for dangerous-condition claims against public entities.

Among other requirements, the plaintiff generally must prove that the property was in a dangerous condition, that the condition created a reasonably foreseeable risk of the type of injury that occurred, and that the condition was a substantial factor in causing the harm.

The plaintiff must also establish either that a public employee's negligent or wrongful act or omission created the dangerous condition or that the entity had actual or constructive notice of the condition with enough time to take protective measures. CACI No. 1100 addresses these elements.

Public-entity cases also have unusually short procedural deadlines.

A claim relating to personal injury generally must be presented to the appropriate government entity within six months under Government Code section 911.2.

California has limited procedures for seeking permission to present a late claim in some circumstances, but those procedures have their own deadlines and requirements. The safest course is to investigate potential public-entity responsibility immediately.

Our dangerous roadway conditions practice explains these claims in more detail.

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How Fault Is Divided Among Multiple Defendants

California follows comparative-fault principles.

If several people or companies contributed to the same injury, a jury can assign percentages of responsibility among them. CACI No. 406 addresses the allocation of responsibility among multiple parties.

A plaintiff's own negligence can also be considered. Under California's pure comparative-negligence rule, a plaintiff who was partly responsible for the crash can generally still recover damages, but the recovery is reduced according to the percentage of fault assigned to the plaintiff.

The allocation of fault among defendants also affects how damages are collected.

Under Proposition 51, codified in California Civil Code section 1431.2, defendants are generally severally liable for noneconomic damages according to their individual percentages of fault. Economic damages are treated differently, and California's joint-liability principles can make the distinction especially important in catastrophic-injury cases.

Medical expenses, future care costs, lost earnings, and other economic losses can be substantial after a serious truck accident. Identifying every responsible defendant and every applicable insurance policy can therefore materially affect the compensation available.

Our guide to the compensation available for truck accident victims discusses the categories of damages that may be recoverable.

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Why Identifying Every Defendant Must Happen Early

Much of the evidence needed to determine truck accident liability is controlled by trucking, logistics, maintenance, and shipping companies themselves.

Depending on the case, important evidence may include:

• electronic logging device records;
• engine control module and other vehicle data;
• driver qualification files;
• hours-of-service records;
• drug and alcohol testing records;
• dispatch communications;
• GPS and telematics records;
• bills of lading;
• broker-carrier agreements;
• equipment leases;
• cargo and weight records;
• maintenance and inspection files;
• roadside inspection reports;
• onboard or outward-facing camera footage; and
• the tractor, trailer, tires, brakes, and other physical evidence.

Some electronic information can be overwritten, and some business records can disappear through ordinary retention practices. Physical evidence can also be repaired, sold, altered, or destroyed.

That is why preservation letters and a focused truck accident investigation should begin as soon as reasonably possible after a serious crash.

The investigation may continue into litigation, when subpoenas, depositions, inspections, expert analysis, and formal discovery can be used to determine how the crash occurred. Our guide to the truck accident litigation process explains what happens after a case is filed.

Determining liability is not simply a matter of asking who was driving. The more important question is which people and companies had the ability and legal responsibility to prevent the crash, what they knew before it happened, and what evidence proves it.

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Talk to Hulburt Law Firm About Your Truck Accident Case

Serious truck accident cases require investigation beyond the police report and the driver at the scene.

Hulburt Law Firm investigates the driver, motor carrier, ownership and leasing relationships, broker, cargo loading, maintenance history, vehicle condition, insurance coverage, and roadway when the evidence calls for it.

Our goal is to identify every person or company whose conduct contributed to the crash and preserve the evidence needed to prove the case.

If you or someone you love suffered a serious injury in a truck accident in San Diego, our San Diego truck accident attorneys, Conor and Leslie Hulburt, can review what happened and explain the available options.

Call (619) 821-0500 or send us a message through our contact form for a free, confidential case review.

There is no attorney fee unless we recover compensation for you.