When seat belts stop short of safety

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Moving Violations

February 2012, Volume 48, No. 2

When seat belts stop short of safety 

James L. Gilbert, Anne M. Dieruf, and Andrew Kim

Seat belts are made to protect people in accidents, but they may not do so adequately. Follow these steps to get the information you need to prove that a defective seat belt failed to prevent your client’s injuries.



Discovery checklist

Seat belt defect cases are often difficult because they challenge the juror’s common perception that automobile crash litigation is about who or what caused the accident. The lawyer must redirect that focus to who or what caused the injuries and whether those injuries should have been prevented by a well-designed safety restraint.1 We do not live in a perfect, accident-free world. We live in the real world, and vehicle safety systems must protect in that environment. Any competent automotive design engineer understands that the only purpose of a seat belt is to provide such protection. But this automotive design philosophy conflicts with auto companies’ litigation philosophy. In defending lawsuits, the automotive industry spends millions of dollars each year emphasizing the importance of the accident in an effort to excuse the performance of its safety equipment. A defective restraint must not be excused on the basis that the client or someone else caused an accident.

To determine whether a seat belt defect may have caused your client’s injuries, answer two questions: Was the client properly belted? And would the injury have been less severe with a well-designed restraint? If you answer yes to both, you have a potential seat belt defect.2

First, know your resources. To build a strong case, you must obtain all available information regarding defect investigations, recalls, safety standards, crash testing, technical papers, similar litigation, internal manufacturer’s documents, and reasonable alterative design information, including patents. There are several excellent resources for this information.3

You will need experts in accident reconstruction, biomechanics, defect engineering, and sometimes human factors analysis of design decisions. Experts with restraint experience are essential, but you should carefully consider expert time management and costs to maximize client recovery.

Next, secure the evidence. Insurance companies often store the vehicle at an independent facility, and a letter requesting that they keep the vehicle is insufficient. Arrange to store the vehicle yourself or get a written agreement that it will be maintained, and ensure it is stored in a locked, indoor facility. Document the chain of custody, including all transfers of possession and inspections, even by your own experts. Before allowing an inspection, require each person attending to sign a log-in sheet, and always videotape and photograph defense inspections. Never allow any alteration of the evidence without agreement of all parties or a court order.

Begin your investigation

First things first.

Review the accident information. Discovering a bad fact shortly before trial may make your case unwinnable. For example, failing to timely discover a prior accident in the subject vehicle will undercut expert opinions that rely on seat belt forensic markings because the marks may have been created in the unrelated accident. While such information might have been unknown to you, it was not unknowable. A detailed pre-suit investigation can help you avoid this situation.

For instance, when medical records reflect an “unrestrained” client, your investigation may reveal that the responding officer unbuckled the belt before emergency responders arrived. The medical technician’s initial “unrestrained” notation may be “pulled forward” through subsequent medical records. Similarly, the investigating officer may report your client was unbelted because he was ejected, but an analysis of police photographs may show the belt not fully stowed, consistent with belt use, and forensics might show the buckle unlatched during the accident.

Early on, take statements from emergency responders and scene witnesses. Consider meeting scene witnesses at the accident site with a videographer and court reporter to document their observations. Obtain all photographs and videotape in original native format to preserve optimal quality.

Thoroughly review the police accident report; officer field notes; police photographs and video; other photographs or video of the scene or vehicle, including surveillance video (from ATMs, for example); records and photographs from fire, rescue, ambulance, and any other responding agency; client and accident witness statements; media reports; towing records; Carfax or other vehicle history report; owner’s manual, warranties, and other vehicle-specific documents; and vehicle titles, registrations, and service documents.

Analyze the injuries. Medical records are considered primarily related to damages, but they are often more important for liability issues. The nature of occupant injuries is key to establishing belt use and performance. A properly designed seat belt should remain on the strongest body parts, such as the pelvis and shoulder. Marks, abrasions, bruising, or other injuries in these areas may prove belt use, and injuries to other areas such as the abdomen, upper thighs, lower arms, or face may indicate poor belt performance. Also, a biomechanics expert with restraint experience can help assess belt usage, possible injury causation theories, and how a safe design would mitigate the injury.

To analyze how the injuries relate to belt use and defect, be sure to review medical and autopsy records as well as injury photographs and video. Also interview medical caregivers and family and friends about their observations of the injuries.

Inspect the vehicle. Identify and document vehicle damage and forensic evidence, including marks and deposits on the vehicle’s interior and seat belts. Such evidence can help determine whether a belt was in proper use during the accident. For example, in a frontal impact, an unbelted occupant may contact the dash, steering wheel, or windshield. Examining such components for damage, bodily fluids, and transfers may demonstrate lack of belt use or a belt failure. The absence of such evidence can help prove belt use.

The seat belt may be marked during an impact. Occupant forces exerted on the restraint can cause marks on seat belt components such as the latchplate, D ring (where the belt attaches to the vehicle above the shoulder), or webbing. (See Figure 1 above.) The webbing may contain blood deposits and cuts or abrasions caused by loading or debris such as broken glass. Latchplate plastic can also be transferred to the webbing. Such marks should be measured and documented in detail.

Downloading a vehicle’s electronic control modules (including air bag and powertrain) is important because it may contain useful information on the accident and seat belt usage.4 Remember to always conduct only nondestructive inspections of the vehicle and seat belts, and obtain a court order or written agreement of all parties before conducting a destructive inspection.

Understand potential defects

Defective belts fail to protect occupants in many ways; the following are some of the most common.

Buckle failure. A defective buckle may unlatch during an accident, allowing occupants to be ejected. Because the webbing may move back into the retractor during an accident, it may appear as if the belt was never on. The challenge is to prove the client was initially belted. In one case, a careful seat belt examination revealed clothing fibers on the webbing in an area not possible if the seat belt was not worn. (See Figure 2 at left.)

Three primary buckle failure modes include false latching, inadvertent unlatching, and inertial unlatching. False latching occurs when the design allows a latchplate to stick in the buckle even when not fully engaged.

Inadvertent unlatching occurs when something (often an elbow) contacts the release button and accidentally releases the belt during an accident because the button is too large, is unguarded, or releases too easily.5 Although Federal Motor Vehicle Safety Standard (FMVSS) 209 does not specify a test, the automotive industry commonly evaluates inadvertent unlatching by applying spheres of various sizes to the release button, simulating accidental contact with an occupant’s elbow. In a properly designed buckle, the belt should remain latched. This test can be easily conducted on exemplar vehicles as well as other competitor vehicles to evaluate alternative designs.

Inertial unlatching occurs when acceleration is sufficient in the direction of the buckle’s release mechanism to generate an inertial force and move the button into a release position. Vehicle damage may indicate the acceleration necessary to release the buckle. For example, considerable wheel rim and axle damage may indicate significant accelerations. A simple alternative design to prevent inertial unlatching is an inexpensive counterweight that blocks this type of unintended release.

Be sure to:

  • Document clothing fibers, marks, and biologic deposits on webbing.

  • Examine photographs for signs that the belt was not fully stowed.

  • Download black box data for “belted status.”

  • Review FMVSS 209 and manufacturer and government testing.

  • Measure force required to release the buckle.

  • Inspect for frayed edges on webbing to show habitual belt use.

  • Interview friends and family regarding habitual belt use.

  • Locate other similar incidents.6

  • Conduct exemplar buckle testing (for all types of failure) and surrogate testing to determine ease of elbow unlatch (inadvertent unlatch).

  • Review manufacturer ball testing (inadvertent unlatch).

  • Review medical records for belt marks (for all types of failure) and elbow bruising (inadvertent unlatch).

  • Inspect buckle release and housing to determine susceptibility to unlatch (inadvertent unlatch).

  • Inspect for debris in buckle housing (false latch).

  • Inspect for evidence of large vertical accelerations (inertial unlatch).

Poor coupling. Belt slack may allow excessive occupant movement, increasing contact injury and ejection risk. The most common reasons for poor coupling include seat belt lockup delay, film spool, and load limiting features. Seat belt lockup delay occurs when a retractor fails to lock up in time, allowing excessive webbing to be released during an accident. Film spool occurs when a load is applied to the belt, causing loosely wound webbing on the retractor to pack down and the webbing to pay out. It can be eliminated by a web clamp that holds the webbing and prevents pack down.

Load limiting features purposely allow introduction of additional webbing at predetermined force levels. One example is a torsion bar in which a deformable shaft allows the retractor spool to rotate and release webbing as the shaft deforms. Although load limiting can prevent certain injuries, it can also increase injury by allowing excessive occupant movement and ejection.

Coupling can be improved with a pretensioner, which uses a pyrotechnic charge to tighten the belt in an accident. (Figure 3, on the following page, shows several types of pretensioners.) This technology is not new; it was introduced in some vehicles in the mid-1980s.7 Moreover, industry testing shows pretensioners dramatically improve belt performance,8 and industry documents show pretensioner costs of only $7 to $10 per seat belt. Despite their availability, effectiveness, and relatively low cost, most manufacturers do not include them in all seating positions.

Evidence consistent with poor coupling includes damage to interior surfaces unlikely to be contacted by a snugly belted occupant and forensic evidence on the belt showing that it did not lock up immediately, including abrasions on the webbing and transfer of plastic from the D ring or latchplate onto the belt. A surrogate study can help determine the amount of webbing payout.

To determine poor coupling:

  • Document damage to vehicle interior, and document and measure marks and damage on seat belts.

  • Perform surrogate study to measure locations where webbing passes through D ring and latchplate; compare to location of accident belt marks.

  • Inspect for pulled stitching on web folds.

  • Remove retractor to document marks and inspect for damage to torsion bar (after notice to all parties).

  • Review medical records for injuries caused by late lockup.

  • Review pretensioner and web clamp testing and literature.

Poor geometry. The belt may shift from the shoulder and pelvis to vulnerable areas such as the abdomen due to improper buckle placement or anchor locations. An inappropriately high buckle can cause “submarining” (the occupant sliding under the lap belt). Poorly located upper anchors can make the shoulder belt uncomfortable, causing misuse or nonuse, and it can decrease restraint effectiveness by allowing the belt to slip off the shoulder. Alterative designs include adjustable upper anchors and seat-mounted restraints. Also, weak seat belt anchors or mounting structures may deform during accidents and degrade seat belt performance. (See Figure 4, above right, for a surrogate comparison showing how anchor deformation can increase excursion and cause injurious contacts.)

Seat belt geometry is especially critical for children and smaller adults. Poor shoulder belt geometry causes the belt to slip off the shoulder, and the occupant’s torso can “roll out,” sometimes causing paralysis. A relatively low buckle position or the addition of an adjustable upper anchor can improve seat belt fit and safety. Industry studies also show that web clamps and pretensioners dramatically improve performance with small occupants. But many vehicles fail to incorporate these features in rear seats, where they are most needed to protect children.

Be sure to:

  • Review medical records for injuries to areas consistent with proper or poor belt fit.

  • Inspect for damage to vehicle interior consistent with occupant contact.

  • Inspect for deformation around belt anchor points.

  • Perform surrogate studies to evaluate signs of poor belt fit and reasonable alternative designs.

  • Perform surrogate study for child with and without boosters, and review booster testing for injury values with and without boosters.

Catastrophic restraint failure. In rare instances, webbing can tear or a component can break. To determine whether this type of failure occurred, inspect for a sharp radius on the latchplate that can fracture seat belt webbing or for signs of contact on the buckle housing or anchor plates. If you discover this type of failure, it is important to interview all relevant scene witnesses to eliminate the possibility that the damaged hardware was caused by post-accident handling or occupant extrication.

Lap-only and passive seat belts. New vehicles rarely incorporate lap-only seat belts, and passive seat belts have fallen out of use, but millions of older vehicles still contain these unsafe designs. Lap-only belts poorly distribute accident forces, are prone to slippage into the weak abdominal area, and do not restrain the upper torso. Passive, or automatic, seat belts also provide inferior protection. Door-mounted passive belts are defeated during accidents where the door opens, and the motorized shoulder belt and separate manual lap belt combination is unsafe because occupants forget to use the lap belt or do not know it is required, resulting in slippage under the shoulder belt or even decapitation.

Prepare to file suit

One of the first decisions in each case is where to file the action. Possibilities include the accident locale, where the plaintiff or survivors reside, where the vehicle was purchased or serviced, where the defendants reside or do business, or where the manufacturer’s LLC members are located. Proper venue selection must consider the law on liability, damages, and evidence, as well as comprehensive jury verdict surveys and court and jury information obtained from lawyers in each potential venue.

At the outset, you should research all potential claims (including strict liability, negligence, breach of express and implied warranty, loss of consortium, negligent infliction of emotional distress, and any applicable state consumer fraud statutes) and potential defenses (including fault apportionment, joint and several liability, contributory or comparative negligence, and non-party fault). Pattern jury instructions are a good starting point. Other important areas of research include choice of law principles, the applicable Daubert or Frye standard, federal preemption, damages elements and caps, and evidentiary issues.

Defendants should include the vehicle manufacturer and the seat belt manufacturer. Because numerous belt manufacturers exist, you should inspect the belts for labels to determine the proper entities to include.9 If your restraint lacks a label, you may be able to identify the manufacturer through research and attorney networking, or you may have to file your case well before the statute of limitations to allow time to discover and add claims against the component maker.

Your overall focus in one of these cases should be to reduce the clutter and complication of the case and make it easy for a jury to find that the accident should not have resulted in this kind of catastrophic injury. You do not want jurors to begin their deliberations by asking questions such as what caused the accident. Rather, they should be asking why the plaintiff had such serious injuries from the accident, what caused them, and whether the seat belt should have better protected them.

James L. Gilbert and Anne M. Dieruf are attorneys at the Gilbert Law Group in Arvada, Colorado. Andrew Kim is a mechanical engineer who directs the firm’s engineering department.


  1. Seat belt defect cases are classified as “crashworthiness” or “enhanced injury” cases. The crashworthiness doctrine holds that a product manufacturer may be liable for defects that cause consumers’ injuries to be enhanced even though they did not cause the underlying accident. See Larsen v. Gen. Motors Corp., 391 F.2d 495, 504 (8th Cir. 1968).
  2. In evaluating a seat belt defect case, you should always also consider whether a defective air bag either contributed to or was the main cause of your client’s injuries. For more information, see Lawrence Baron, The ‘Smart’ Air Bag Case, Trial 40 (Feb. 2007).
  3. They include AAJ’s information databases and networking opportunities; Attorneys Information Exchange Group, www.aieg.com/ (facilitates work-product sharing with other lawyers with similar cases and maintains defect databases, including technical papers, legal pleadings, depositions and trial transcripts, and manufacturers’ internal documents); Safety Research & Strategies, Inc., www.safetyresearch.net/ (automotive defect case evaluation and safety research and information); National Highway Traffic Safety Administration, www.nhtsa.gov/ and www.safercar.gov/ (crash injury and injury prevention research, vehicle and component research, testing, safety ratings, investigations, test procedures, crash statistics, seat belt laws and regulations, rulemaking and manufacturers’ comments, and links to accident data); Center for Auto Safety, www.autosafety.org/ (information on vehicle-specific defects and recalls, and articles and documents on defect investigations and automotive safety laws); Insurance Institute for Highway Safety, www.iihs.org (crash test results and information about vehicles, child seats, and safety).
  4. To download a vehicle’s “black box” or accident data recorder (ADR), you must obtain the written consent of all defendants, acquire necessary background documents from the ADR supplier, and hire a download expert. For more information, see Steven Schorr & R. Scott King, Beyond Black Boxes, Trial 32 (Feb. 2011).
  5. Federal Motor Vehicle Safety Standard 209 requires that the “buckle release mechanism shall be designed to minimize the possibility of accidental release.” 49 C.F.R. §571.209(e) (2010).
  6. See the resources listed in note 3 above.
  7. See e.g. Bill Gustafsson, Volvo’s History of Putting Safety First, 51 Socy. Automotive. Engrs. Austraslasia J. 43 (1991); Willi Reidelbach, Recent and Future Improvements in Seat Belt Design, in Procs. of 6th Intl. Conf. of Intl. Assn. for Accident & Traffic Med. 218 (IAATM 1977); Willi Reidelbach & Hansjürgen Scholz, Advanced Restraint System Concepts, Socy. Automotive Engrs. No. 790321 (1979).
  8. See e.g. Jüergen E. Mitzkus & Heinz Eyrainer, Three-Point Belt Improvements for Increased Occupant Protection, Socy. Automotive Engrs. No. 840395 (1984).
  9. Remember to preserve any marks or other evidence on the belts and carefully maintain the post-accident position of the belts and webbing.


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