Trucking Safety Resource Center Arnold & Itkin LLP
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Carrier Negligence

Disabled or Malfunctioning Safety Systems

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Arnold & Itkin Research Team

Reviewed by Kala Sellers

Commercial trucks increasingly ship from the factory or are retrofitted with advanced driver assistance systems (ADAS) designed to prevent or mitigate the very crashes that produce the most catastrophic injuries. Automatic emergency braking (AEB) detects an imminent rear-end collision and applies the brakes without driver input. Forward collision warning alerts the driver to closing distance on the vehicle ahead. Lane departure warning detects when the truck drifts out of its lane without a turn signal. Stability control intervenes when the truck begins to lose directional stability or approaches a rollover threshold. Each of these systems addresses a specific, documented category of crash, and each of them works: an Insurance Institute for Highway Safety study of large trucks found that AEB reduced rear-end crashes by 41 percent, and forward collision warning reduced them by 44 percent.[1] When either system could not prevent the crash entirely, it reduced the truck’s impact speed by more than 50 percent between the warning or intervention and impact, which IIHS links to reduced crash severity.[2]

IIHS LARGE TRUCK STUDY
41%
Automatic emergency braking reduced rear-end crashes by 41 percent.
44%
Forward collision warning reduced rear-end crashes by 44 percent.
50%
Where the crash was not prevented entirely, impact speed fell by more than 50 percent between the warning or intervention and impact.
Insurance Institute for Highway Safety study of large trucks.

The question in litigation is rarely whether the technology exists. It is whether the technology was functioning at the time of the crash. A truck equipped with AEB that rear-ends a stopped vehicle raises an immediate question: did the AEB system activate? If it did not, why not? Was the system disabled by the driver? Was it malfunctioning because of a sensor obstruction, a software fault, or a hardware failure? Was the carrier aware that the system was not functioning, and did it dispatch the truck anyway? The answers determine whether the crash was the product of driver error alone or the product of a carrier’s decision to operate a truck with a known safety deficiency, turning an avoidable crash into one that the technology installed on the truck was specifically designed to prevent.

For trucks currently on the road, no federal regulation requires AEB, forward collision warning, or lane departure warning beyond the existing FMVSS No. 136 electronic stability control requirement for certain heavy vehicles.[3] In June 2023, NHTSA and FMCSA jointly proposed a new Federal Motor Vehicle Safety Standard No. 128, which would require AEB systems on new heavy vehicles subject to FMVSS No. 136, responding to a mandate in the Bipartisan Infrastructure Law directing the Department of Transportation to prescribe an FMVSS requiring AEB on heavy commercial vehicles equipped with electronic stability control.[4] As proposed, truck tractors and certain large buses already subject to FMVSS No. 136 (generally those above 26,000 pounds GVWR) would have three years to comply after a final rule, with vehicles not yet subject to FMVSS No. 136 (generally Class 3 through 6 vehicles) given four years.[5]

PROPOSED COMPLIANCE PERIODS
3 YEARS Vehicles Already Subject to FMVSS No. 136 Truck tractors and certain large buses, generally those above 26,000 pounds GVWR, would have three years to comply after a final rule.
4 YEARS Vehicles Not Yet Subject to FMVSS No. 136 Generally Class 3 through 6 vehicles would be given four years.

Critically for the question of disabled systems, the 2023 proposal would also add Federal Motor Carrier Safety Regulations requiring carriers to keep AEB and ESC systems on during vehicle operation.[6] FMCSA’s proposed regulation would require motor carriers operating CMVs manufactured subject to FMVSS No. 136 to maintain and use the required AEB devices as prescribed by NHTSA whenever the vehicle is operating.[7] NHTSA’s base proposal would not permit a manual switch to deactivate AEB above 6 mph; the agency separately sought public comment on an alternative under which a switch could be permitted if it defaulted to “AEB ON” with every cycle of the starting system. Under either version, deliberate deactivation of a mandated AEB system would become a federal violation rather than merely a breach of a carrier’s internal policy, if and when a final rule takes effect.[8]

As of mid-2026, that “if” still matters. The 2023 proposal was never finalized: an expected 2025 final rule was paused for administration review, and FMCSA and NHTSA have since set aside the original 2023 proposal in favor of a new supplemental rulemaking, expected around mid-2026, that will restart the public comment process. Industry reporting suggests a final rule is unlikely before 2027 or 2028. Part of the delay traces to a separate NHTSA inquiry into AEB false activations, opened in 2023 and upgraded to a formal engineering analysis in October 2025, which remains open. For trucks already equipped with AEB voluntarily (which is most of the fleet today, since no mandate yet exists), the relevant standard in litigation is not the pending rule but the carrier’s existing maintenance obligations. A carrier that equips its trucks with AEB has made a safety investment; a carrier that allows that investment to degrade into a non-functioning system has created a condition arguably worse than never installing the technology, because the system’s presence creates an expectation of protection that is not being delivered.[9]

How Safety Systems Fail

Advanced driver assistance systems on commercial trucks fail through several mechanisms, some attributable to the operating environment and some attributable to the carrier’s maintenance practices.

FOUR FAILURE MODES
Sensor Obstruction
Forward-facing radar units and cameras are exposed to road spray, mud, ice, snow, and insect debris.
Software Faults
Updates, compatibility issues, or programming errors can cause a system to behave unpredictably.
Hardware Failures
Damaged radar units, camera misalignment from windshield replacement, wiring damage, and control module failures.
Deliberate Deactivation
Some ADAS configurations allow the driver to disable or adjust the sensitivity of individual systems.

Sensor obstruction is the most common cause of degraded ADAS performance. AEB and forward collision warning systems rely on forward-facing radar units and cameras mounted on the front of the cab, typically behind the windshield or on the bumper. These sensors are exposed to road spray, mud, ice, snow, and insect debris. A radar unit covered in road grime may lose the ability to detect vehicles ahead at the correct range; a camera lens obscured by dirt, condensation, or frost may fail to classify objects accurately. When sensor inputs are degraded below the system’s operating threshold, the system typically enters a reduced-capability mode or deactivates entirely.[10] Commercial ADAS platforms such as Bendix Wingman Fusion are designed to generate a dashboard malfunction indicator when the system detects that a component or sensor has fallen below its functional threshold, but that warning is only useful if the driver reports it and the carrier acts on it.

Software faults can cause systems to fail intermittently or completely. ADAS software is complex, and updates, compatibility issues, or programming errors can cause a system to behave unpredictably. A system that functions correctly in most conditions but fails to activate under specific circumstances (a particular closing speed, or a specific type of lead vehicle) may have a software-related limitation the carrier knew or should have known about through manufacturer service bulletins or its own fleet’s experience with the system.

Hardware failures include damaged radar units from minor front-end impacts, camera misalignment from windshield replacement, wiring damage from rodent activity or vibration, and control module failures from electrical surges or water intrusion. A truck that has sustained any front-end damage, even a minor parking lot impact or a strike from road debris, may have ADAS sensors that are physically intact but no longer properly aligned. Recalibration after any event that could affect sensor positioning is a standard manufacturer requirement, and failure to perform it leaves the system operating with degraded accuracy that may not be apparent until it fails to respond to a real hazard.

Deliberate deactivation by the driver is the simplest and most consequential failure mode. Some ADAS configurations allow the driver to disable or adjust the sensitivity of individual systems through dashboard or steering-wheel controls. Drivers who find forward collision warning too sensitive in heavy traffic, or who experience false AEB activations (the same false-activation concern that has drawn NHTSA scrutiny and contributed to delay in the federal mandate) may turn the system off and never turn it back on. On systems such as Bendix Wingman Fusion, the system’s status (active, inactive, or reduced-sensitivity mode) is recorded by the system’s control module and is recoverable through a diagnostic download using tools such as Bendix ACom diagnostic software.[11]

The Carrier’s Maintenance Obligation

Once a carrier installs ADAS technology on its trucks, the technology becomes part of the vehicle the carrier is obligated to maintain. Under 49 C.F.R. § 396.3(a), every motor carrier and intermodal equipment provider must systematically inspect, repair, and maintain all motor vehicles subject to its control, and § 396.3(a)(1) requires all parts and accessories to be in safe and proper operating condition at all times, listing components “including but not limited to, frame and frame assemblies, suspension systems, axles and attaching parts, wheels and rims, and steering systems.”[12] The phrase “including but not limited to” means the list is illustrative, not exhaustive. ADAS components that affect the safety of the vehicle’s operation reasonably fall within the scope of the carrier’s maintenance obligation even though they are not specifically enumerated in the regulation.

Under 49 C.F.R. § 396.7(a), a motor vehicle may not be operated in a condition likely to cause an accident or breakdown.[13] A truck with a disabled AEB system operating in rear-end crash conditions, such as heavy interstate traffic, is a vehicle whose crash risk has been increased by the absence of a functioning safety system. If the carrier knew the system was not functioning, dispatching the truck in those conditions reflects a decision to accept a higher level of crash risk than the truck was equipped to manage.

Under 49 C.F.R. § 396.13, before driving, a driver must be satisfied the vehicle is in safe operating condition and, where a driver vehicle inspection report (DVIR) was required for the prior trip under § 396.11(a)(2)(i), must review that report and sign to certify that any required repairs were performed.[14] ADAS malfunction indicators visible on the dashboard during a pre-trip inspection fall within the scope of that inspection. A driver who notes an AEB malfunction warning on the DVIR has documented the deficiency and triggered the carrier’s obligation to repair it before dispatching the truck again; a driver who ignores the warning and does not note it has failed to conduct an adequate inspection, and a carrier that dispatches without confirming the certified repair was actually made has failed its own sign-off obligation.

Three Duties That Apply
49 C.F.R. § 396.3(a)
Every motor carrier and intermodal equipment provider must systematically inspect, repair, and maintain all motor vehicles subject to its control, and all parts and accessories must be in safe and proper operating condition at all times.
49 C.F.R. § 396.7(a)
A motor vehicle may not be operated in a condition likely to cause an accident or breakdown.
49 C.F.R. § 396.13
Before driving, a driver must be satisfied the vehicle is in safe operating condition and, where a driver vehicle inspection report was required for the prior trip, must review that report and sign to certify that any required repairs were performed.
ADAS components that affect the safety of the vehicle's operation reasonably fall within the scope of the carrier's maintenance obligation even though they are not specifically enumerated in the regulation.

The carrier’s telematics system may provide an additional layer of monitoring. Many fleet management platforms track ADAS system status, including whether AEB is active, whether forward collision warnings are being generated, and whether the driver has disabled any systems. A carrier with access to this data that does not review it has chosen not to monitor the functioning of safety equipment it installed. A carrier that reviews the data, sees that a driver has disabled AEB on every trip for the past three months, and takes no corrective action has documented both its knowledge and its indifference.

Why the Absence of a Mandate Does Not Eliminate Liability

The fact that no federal regulation currently requires AEB does not mean a carrier bears no responsibility for ensuring a system it installed continues to function. The legal analysis in a negligent maintenance case does not depend on whether the component was federally mandated. It depends on whether the component was installed on the vehicle, whether it affected the safety of the vehicle’s operation, and whether the carrier maintained it in working condition.

A carrier that voluntarily installs AEB on its fleet has established its own safety standard: our trucks will have the capability to detect imminent rear-end collisions and apply the brakes automatically. When a truck in that fleet rear-ends a stopped vehicle and the AEB was not functioning, the carrier’s own standard becomes the benchmark against which its conduct is measured. The question is not whether a regulation required AEB. The question is whether the carrier maintained the AEB system it chose to install, and whether a functioning system would have prevented or mitigated the crash.

NOT THE QUESTION
✓Whether a regulation required AEB.
✓Whether the component was federally mandated.
THE ACTUAL QUESTION
✓Whether the component was installed on the vehicle.
✓Whether it affected the safety of the vehicle's operation.
✓Whether the carrier maintained the AEB system it chose to install.
✓Whether a functioning system would have prevented or mitigated the crash.

The IIHS data supplies the causation link. If AEB reduces rear-end crashes by 41 percent, a carrier that allowed its AEB to remain non-functional on a truck that subsequently rear-ended another vehicle operated a truck that was measurably less safe than the carrier’s own fleet standard. If a functioning system would have prevented the crash, or reduced the impact speed by more than half, the carrier’s failure to maintain the system is a proximate cause of the injuries that resulted from the full-speed impact.[15]

In jurisdictions that permit punitive damages for conscious disregard of safety, a carrier that knew the AEB was disabled (through telematics data confirming the driver had turned it off, DVIR notations of malfunction indicators, or maintenance records showing the system had not been serviced after a front-end impact) and still dispatched the truck faces exposure beyond compensatory damages. The evidence of knowledge comes from the carrier’s own records; the evidence of indifference comes from the absence of any corrective action in response to them.

What Discovery Should Target

  • Discovery in a disabled safety system case should capture the system’s status at the time of the crash, the carrier’s knowledge of any deficiency, and the carrier’s maintenance and monitoring practices. Useful categories include:
  • The ADAS control module download from the truck, showing system status, activation history, malfunction codes, and any driver-initiated deactivation events.[16]
  • All telematics data for the truck and driver showing ADAS system status, forward collision warning events, and AEB activations for the 90 days preceding the crash.
  • All DVIRs for the truck covering the 90 days before the crash, with attention to any notations of ADAS malfunction indicators, warning lights, or system deactivation.
  • The truck’s maintenance records under § 396.3, with attention to any ADAS-related service, sensor calibration, software updates, or component replacements.
  • Any manufacturer service bulletins or technical service information related to the ADAS system installed on the truck.
  • The carrier’s written policies on ADAS use, including any rules on driver deactivation of safety systems and any monitoring protocols for system status.
  • All internal communications regarding the ADAS system, including reports of false activations, driver complaints about system sensitivity, or management decisions to allow drivers to disable the systems.
  • The carrier’s training records on ADAS use, including whether drivers were trained on the systems’ functions, limitations, and the carrier’s policy on keeping the systems active.
  • The objective is to establish that the ADAS system was installed, that it was not functioning at the time of the crash, that the carrier knew or should have known the system was not functioning, and that a functioning system would have prevented or mitigated the crash.
DISCOVERY TARGETS
ADAS control module download Telematics data DVIRs Maintenance records Manufacturer service bulletins Written policies on ADAS use Internal communications Training records on ADAS use

Sources

Frequently Asked Questions

  • Not automatically. Whether a particular safety system was federally required is one factor, but it isn't the deciding one. Courts look at whether the system was actually installed on the truck, whether the carrier knew or should have known it wasn't working, and whether a functioning system would have prevented or reduced the severity of the crash.
  • Discovery can target the ADAS control module download showing system status and activation history, telematics data showing whether the system was active in the months before the crash, driver vehicle inspection reports noting any malfunction warnings, maintenance records related to the system, and the carrier's internal policies and communications about driver deactivation of safety systems.
  • Several ways: dirt, ice, or road grime can obstruct the radar or camera sensors; software glitches can cause the system to behave unpredictably; a minor collision or windshield replacement can knock sensors out of alignment without visible damage; and drivers can manually disable the system, sometimes because they find it too sensitive or experience false activations, and simply never turn it back on.
  • Yes. Liability doesn't depend on whether a regulation mandated the technology. It depends on whether the carrier installed the system, whether it affected the safety of the truck's operation, and whether the carrier maintained it in working condition. A carrier that voluntarily equips its trucks with AEB has set its own safety standard, and a truck that rear-ends another vehicle with a non-functioning AEB system can be measured against that standard, along with the carrier's general maintenance obligations under federal trucking regulations.
  • Not yet. As of mid-2026, no federal regulation requires AEB, forward collision warning, or lane departure warning on commercial trucks beyond the existing electronic stability control requirement (FMVSS No. 136) for certain heavy vehicles. NHTSA and FMCSA proposed a rule in 2023 that would mandate AEB, but that proposal was never finalized, and the agencies are now working on a new supplemental proposal expected around mid-2026. A final rule is unlikely before 2027 or 2028.