What Qualifies as a Low-Impact Crash?

Photo by Compagnons on Unsplash

A total of 6.14 million accidents occurred in 2023, as reported by the NHSTA. Data reveals that these incidents injured 2.44 million people. Side-impact and head-on collisions amount to 23% of collisions. 41% of the cases involved severe injuries.

An incident wherein a slow vehicle bumps into another is called a low-impact crash. Insurance companies often use these types of crashes as a specific litigation strategy to deny or minimize injury claims. The premise of the argument centers on the minimal amount of damage, which would make it physically impossible to cause the claimed injuries.

Biomechanical experts take this standpoint in a significant number of soft tissue injury litigations, particularly in certain rear-end crashes that occur at low to moderate speeds.

For those claiming compensation after a low-impact incident, it is particularly important to understand how to protect their rights during discussions about a minor impact crash. What are those arguments, and what evidence do they require? And what are the scientific objections to the definitions on which they are premised?

Let’s learn what a low-impact car accident is and what cases qualify for this category.

The Insurance Industry’s Biomechanics Defense

The low-impact crash defense begins with a delta-V analysis. This analysis is a calculation of the change in velocity of the struck vehicle during the collision event. Insurance-retained biomechanical engineers analyze the crash data, vehicle damage photographs, and engineering parameters to estimate the speed differential between the vehicles. They then apply injury threshold literature to argue that the specific crash could not have injured the plaintiff. They cite studies suggesting that the average person can tolerate a delta-V of five to ten miles per hour without sustaining injury.

This defense has a superficially compelling logic: visible damage is intuitive evidence of force, and minimal damage suggests minimal force. The scientific literature underlying it can be substantially contested. The studies most commonly cited in low-impact crash defense were conducted on healthy young adults with normal musculature and no pre-existing conditions. These crashes happened in controlled laboratory settings using seats and restraints that do not replicate the variation in real-world vehicles. They do not reflect the injury experience of older adults, people with pre-existing cervical conditions, people who were not anticipating the impact, or occupants in vehicles whose seat characteristics absorb energy differently than laboratory test equipment.

The relationship between vehicle damage and occupant injury force is not straightforward. Modern vehicle bumper systems are engineered specifically to resist and absorb low-speed impacts to minimize repair costs. This design choice can reduce property damage, but it may also transmit more force to the occupant. 

A crash that produces minimal bumper damage may have transmitted more force to the seated occupant than one that produced more visible damage to a less rigid bumper structure. Defense experts who rely solely on vehicle damage photographs as a proxy for occupant force transmission are applying an oversimplified model that peer-reviewed biomechanics literature has criticized.

Why Minor Crashes Can Cause Significant Injuries

According to the law firm website https://blakejoneslaw.com/, the most common forms of injuries for rear-end crashes include whiplash, seatbelt injuries, concussions, and injuries to the arms and wrists.

The mechanisms by which low-speed rear-end crashes produce cervical soft tissue injury are well-established in the clinical literature and supported by research that is independent of litigation contexts. In the event of an abrupt collision from the rear, the occupant’s torso may move before the head does. Following this sudden movement, the neck may snap into motion due to the unexpected change in velocity. This outcome can force pads of muscle to stretch or tear. The sudden movement may also affect the ligaments, joints, and disks within the cervical area of the spine.

Several occupant factors increase the risk of injury at low delta-V values. Unpreparedness significantly increases the injury-producing potential of a given delta-V. This scenario happens when the occupant is not anticipating the impact and therefore has relaxed neck musculature at the moment of collision.

When the occupant was looking to the side at the moment of impact, it may have caused head rotation. In this case, it places the cervical spine in a biomechanically disadvantaged position that increases force on specific structures. 

Small stature relative to the vehicle seat can result in inadequate head restraint function. This scenario is when the occupant’s head rests above the active headrest zone. Pre-existing cervical conditions like degenerative disc disease or prior injury can make the cervical spine more susceptible to injury from forces that would not injure an unaffected spine. None of these occupant-specific factors are captured in studies on injury thresholds at the population level.

The Eggshell Plaintiff Doctrine

Eggshell plaintiff doctrine or thin skull rule, is the argument that once an injury has happened, the person who causes the injury is fully liable for the injury regardless of whether the injured party has a preexisting condition or not that made the injury more severe. Liability can still be assigned to a defendant who causes injury to a person suffering from pre-existing conditions and who is particularly susceptible to injury. The defendant cannot reduce liability by arguing that a healthier plaintiff would not have been injured by the same force. When applied to low-impact crash cases, the doctrine means that an older plaintiff with pre-existing cervical degenerative disc disease who is injured in a crash that would not have injured a younger, healthier plaintiff is still entitled to full compensation for the injury the crash actually caused. 

The eggshell doctrine is well-established in most states but requires that the plaintiff’s injury be causally connected to the defendant’s negligence. The defense does not intend to challenge the doctrine itself. Instead, they will challenge the part they perceive as a causation issue, arguing that the plaintiff’s symptoms are linked to a prior condition and not to the crash itself. Differentiating a stable pre-crash condition that exhibited no symptoms or only slight symptoms from a post-crash condition that was exacerbated or developed symptoms is a situation that must be proven by the available medical records. Specialized expert medical help is important in shaping the clinical picture both prior to and following the crash.

Evidence That Supports a Low-Impact Injury Claim

Crash documentation: Gather the police report, pictures of the car taken at a different angle, photos of the two cars involved in the accident, and any video that can help explain the impact of the crash. These documents are the things that are used to establish the severity of the crash. Property damage estimates and repair records provide objective documentation of the impact’s effects on the vehicles. This documentation is the foundation for the plaintiff’s biomechanical counter-argument. In some cases, an accident reconstructionist is involved and presents a different analysis of the forces involved than the defense expert.

Continuity of medical records: The best evidence for the success of a low-impact injury claim is the existence of a gap-free, consecutive medical record that demonstrates the occurrence of symptoms immediately after or in the days following the crash. Coherent treatment instructions, including apparent objective clinical findings, help to back a case of low-impact injuries.

Delays in medical attention or very few medical records may be a source of difficulty in establishing a connection between an injury and an incident. It is much more helpful to immediately visit your nearest physician and disclose any forms of discomfort at the earliest. These stages of action apply strength to your claim in such a way that they clearly provide insight as to what really happened.