Most injuries sustained in road traffic accidents involve occupants wearing seat belts. This article offers a medical expert’s view on the issues that may arise when a seat belt was not worn, or when it is not known whether a seat belt was worn or not.
Medical evidence has overwhelmingly shown that seat belts can prevent deaths and serious injuries in road traffic accidents. Wearing them is compulsory in the UK, although a medicolegal expert should be aware that a claim can be modified, usually reduced, to take into account failure to wear a seat belt.
If an issue is raised that no seat belt was worn, the expert should be prepared to consider a subsequent set of questions, to assist the court. These might include consideration as to what injuries might have been less severe or not occurred had a seat belt been worn, or what injuries might have been greater or have occurred had a seat belt been worn. These questions are easy to pose by lawyers but complex to consider from a medical point of view.
As a general principle, at low and moderate velocity impacts, seat belts restrain the torso and prevent the torso and head from striking the steering wheel and the windscreen. This is based on the assumption, which may of course be tested, that the seat belt was fitted correctly and was being worn correctly. Seat belts do not prevent injuries to flailing limbs. At high-velocity impacts, seat belts also normally prevent ejection from a vehicle and affect the injuries sustained.
Also, as a general principle, seat belts do not prevent injuries due to lateral deforming forces, such as caused by side impacts; nor do they prevent injury due to rotational forces, such as a spinning car.
Low-velocity impact
At a very low velocity, there is a contradictory concept, whereby a gentle force impact might not be sufficient to cause whiplash type injury. Wearing a seat belt, by restraining the torso, allows a greater differential and sudden movement between the torso and the head, increasing the risk and severity of whiplash. If a seat belt had been worn in a low-velocity impact accident, then it is likely that a whiplash injury might have occurred or been more severe. This concept may be important for the apparently simple fixed cost (MedCo) reports, and the legal teams need to be aware that a simple concept of financial deduction for not wearing a seat belt may not be appropriate.
Moderate velocity impacts
For moderate velocity impact accidents, seatbelts tend to save truncal injuries and head injuries, but not necessarily limb injuries or whiplash injuries.
Without a seat belt, injuries to the trunk can be caused by the body moving forward and directly impacting on the internal vehicle structures. There is an inevitable logic that these injuries would have been prevented by the use of a seat belt.
However, as the velocities increase further, then a variety of injuries can still be caused by sudden deceleration. The deceleration can occur because the torso is held in the seatbelt and decelerates with the car or the body is projected forward without a seatbelt and strikes the internal vehicle parts, the same relative deceleration occurs when the body is stopped by the car parts. In either case, injuries due to deceleration can occur, irrespective of seatbelt usage.
The above considerations apply to the concept of the forces involved being forward and backward, in which case a seat belt offers a restraint. If the forces involved are sideways forces, then seatbelts are very poor at restraint, and may not prevent injuries due to side forces even if worn.
If there is an intrusion of the car frame into the passenger compartment, then the concept of moving vehicle components hitting the static body applies, and seatbelts cannot prevent injuries due to intrusion. This is most obvious in roll-over accidents, with the intrusion of the car roof causing head injuries, which would not have been prevented by wearing a seat belt.
High-velocity impact accidents
In high-velocity impact accidents, often involving deaths, questions may arise as to whether a seat belt was being worn, and whether any medical evidence can help determine the answer. Under such circumstances, the primary evidence is engineering with respect to investigating the vehicle itself, and inspection of the seat belt. The medical aspect relates to considering the pattern of injuries actually sustained, and the possible causes for those injuries.
In high-velocity impact accidents, with significant vehicle damage, the position of the seat before and after impact and intrusion of vehicle body parts may be of great significance, and the medical expert may therefore need expert engineering evidence to assist in determining what injuries may have been suffered had a seat belt been worn.
When dealing with complex issues, it is important to note that engineering experts often deal with speed calculations, and calculate forces involved derived from speed calculations measured in newtons, a measure of force. Medical literature relates injuries to G-force, a measure of acceleration – so there is often a discrepancy between the physics described in engineering reports and medical reports.
Also, injury is thought to be caused by peak G-force, not average G-force, meaning that simple considerations of apparent forces may be misleading in scientific terms, it is usually impossible to measure the exact force applied to the body parts, and the measures used are proxies for the actual force, speed being one proxy, and damage to the car/intrusion being another. These proxies are good rules of thumb, but not absolute in their accuracy.
For such high-velocity impact accidents, there are patterns of injuries associated with seat belt usage. These would include truncal injuries, where the seat belt impacts the chest.
Bruising from seat belts may be evident, but not well documented in the medical records. Clinical notes tend to concentrate on the severe injuries that need treatment. Descriptions of bruising may be restricted to the nursing notes or post-mortem reports, and the medical notes such as described may be ‘hidden away’ on one sheet only in the notes, yet great significance when dealing with this particular problem.
Deceleration injuries, especially internal injuries, can still occur, and a medical expert would need to consider whether such injuries might have occurred had a seat belt been worn. For a complex claim, each injury would need to be considered, and careful consideration given to whether other injuries might have occurred had a seat belt been worn.
A more contentious issue relates to injuries sustained by other occupants of the vehicle. From a medical point of view, injuries sustained by other occupants can be a poxy for the forces involved in the impact. Their injuries and their seat belt status can Influence considerations for the claimant under question. However, there is a legal challenge for the teams involved in obtaining the correct permission to release the medical details of other injured parties to the expert.
An expert asked to address such matters for a high-velocity impact accident, therefore, need the full medical notes including any ambulance records, engineering evidence including the police and investigation reports, and other medical evidence – such as post-mortem reports and medical evidence of injuries to other parties. Witness statements can be of assistance, as the condition of the claimant immediately after the accident – level of consciousness, breathing, not breathing, gasping etc – can help in the consideration as to whether survival might have occurred if a seat belt had been worn.
Deductions for Failure to Wear a Seatbelt
In the leading case of Froom Lord Denning held that a person who suffered more severe injuries as a result of the failure to wear a seat belt could be held contributorily negligent, even though it was not obligatory to wear a seatbelt at that time and he was blameless so far as the cause of the collision was concerned. Though the accident was caused by the defendant’s bad driving, the damage was caused in part by the bad driving and in part by the failure to wear a seat belt. In those circumstances, the reduction of the compensation would depend upon the difference that a seatbelt would have made
- There would be no reduction where the seatbelt would have made no difference.
- Where the evidence showed that the failure to wear a seatbelt “made all the difference” and “the damage would have been prevented altogether”, then there would be a reduction of 25%.
- Where the evidence showed only that the seatbelt would have “made a considerable difference”, the reduction should be 15%.
If you have suffered an injury in a Road Traffic Accident and need further advice please contact Richard Meggitt, Solicitor 0114 2678780, or email [email protected]
