In the first instance, the Judge heard expert evidence from two road safety engineers who agreed a properly worn belt would probably have been helpful in reducing the severity of the head injury but found that complete prevention of a “serious head injury” would have been unlikely even had he worn a belt.
The Judge therefore declined to find any contributory negligence.
She said it had not been shown that a belt, if worn, would have reduced the injuries sufficiently as to entitle her to make a deduction. She said she had to be satisfied that the failure to wear a belt had made a considerable difference (applying the test of the leading case of Froom -v- Butcher) .
She said she needed medical evidence to come to that conclusion and there was none on this point. This judgment was appealed. The defendant said the engineers had sufficient expertise to give a comment on the point.
They said that language of Froom -v- Butcher ought to be reconsidered in light of developments since it was decided.
The Court of Appeal said the Judge was entitled to listen to engineers if they were capable of assisting the court and it was possible they could in theory. However in this case, they had not given clear and definite evidence on the crucial issue of whether the brain damage would have been significantly less if the belt had been worn.
They had not made clear to what degree they said the serious head injury could have been prevented had he been wearing his belt or what they termed serious injury, for example, whether a seat belt would have reduced the injury to mild concussion or facial fractures or temporary brain damage.
The court did not find that medical evidence on “the difference” was a necessity in every seatbelt or head injury case (contrast the remarks in the recent cycle helmet litigation of Smith v Finch).
However, the Judge felt that the engineering evidence had not shown on a balance of probabilities that a seatbelt would have reduced the injury to a sufficient degree to require reduction for contributory negligence. That is a fine judgement and one the Judge was entitled to make on the day.
There was also a good policy reason to follow Froom -v- Butcher. Those who litigate were entitled to have some certainty as to how cases would be managed and decided.
Froom -v- Butcher establishes the principle that a deduction of 15 per cent for contributory negligence is appropriate if a seatbelt would have made a considerable difference to the extent of injury. There is a powerful public interest in avoiding intensive enquiry into fine degrees of contributory negligence so that the vast majority of cases can be settled according to a well understood formula and exceptional cases did not get out of control. Froom -v- Butcher was to be followed.
Stanton -v- Collinson  EWCA CIV 81.