Smith v Co-Operative Group Limited & Mark Hammond

Judge not entitled to reject expert evidence simply on the basis of his own experience but must give reasons as to why he does not accept it

[2010] RTR 30, [2010] EWCA Civ 725 TEDR Volume 15 Issue 3

The Facts

This was a case where a 13 year old boy, on his bicycle, cycled out of a driveway and into the road where he was struck by an oncoming vehicle.

The main issue in the case was, plainly, whether the driver could or should have done more to avoid an accident. In particular, there was much debate about whether he could have sounded his horn, thus attracting attention to himself and avoiding the accident.

The Trial Judge held that the driver has been negligent in failing to sound his horn. In fact, that was the only finding of negligence on his behalf.

Thereafter, the Trial Judge considered expert evidence called on behalf of the driver. In essence, the evidence was that even had the driver sounded his horn, the accident would have been inevitable. The Judge rejected the evidence of the Expert, preferring to rely upon his own experience of reacting to the sound of a horn when driving.

The issue

Was the Judge entitled to reject the evidence of the expert on this basis?

The Decision

Lord Justice Moore-Bick held that, whilst the Judge was not bound to accept the Expert evidence if he had good grounds for not doing so, if he was going to reject it, he should have given reasons rather than just rely upon his own experience of driving. His Lordship noted that whilst it was tempting for a Judge to use his own experience, layman’s perception of matters could well be wide of the mark and thus, the temptation should be resisted.

Overall, there was no satisfactory reason for rejecting the evidence of the expert and thus the appeal was allowed.


Expert evidence can, of course, be rejected if there are reasons for so doing, however, ordinary layman’s perceptions ought not to displace expert opinion. Experts should be prepared to demonstrate why it is that the layman’s explanation is wrong or flawed if necessary.

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