Darg v Commissioner of Police for the Metropolis

In a personal injury claim, causation is determined on the balance of probabilities by evaluating the whole evidential picture, including expert evidence and the facts proved. The fact that the causal mechanism is unusual or medically improbable does not automatically create an exceptional case in which causation cannot be established. Where competing explanations are advanced, the court may prefer one body of expert evidence after assessing the evidence as a whole. A claimant may establish causation even where the alleged injury is an unusual cause of the subsequent condition.

The claimant suffered finger lacerations while working on a police vehicle. He later developed carpal tunnel syndrome, underwent decompression surgery and developed complex regional pain syndrome. Liability for the accident was admitted, but the defendants disputed whether the accident caused the carpal tunnel syndrome and challenged the extent of the claimant’s continuing disability and loss of earnings.

The court considered competing medical evidence, contemporaneous records, witness evidence and surveillance footage. The central issues were whether there was continuity of symptoms linking the accident to the carpal tunnel syndrome and what level of disability and earning capacity resulted.

1. Causation. The claim succeeded on causation. The court found that swelling followed the injury and that there was continuity of carpal tunnel symptoms from shortly after the accident until the claimant’s examination by the hand surgeon.
2. The contemporaneous medical records were incomplete and inaccurate in places. Their failure to record swelling or continuing symptoms did not establish that those matters were absent. The letter of claim, the claimant’s evidence and the evidence of causation witnesses supported continuity of symptoms.
3. The court rejected the defendants’ reliance on Rhesa Shipping Co SA v Edmunds [1985] 1 WLR 1948. This was not an exceptional case of competing explanations each being inherently improbable. The court was entitled to assess the range of expert evidence and decide which evidence it preferred.
4. The court preferred Dr Huskisson’s evidence that injury-related swelling could cause swelling in the wrist and carpal tunnel, leading to carpal tunnel syndrome. The evidence of Mr Fleming and, ultimately, Dr Wright supported that conclusion.
5. The claimant had a genuine continuing disability, but had exaggerated its severity by presenting the worst periods as normal. The surveillance evidence showed that he could drive, walk, use a computer and shoot, although his condition fluctuated and caused pain and fatigue.
6. The claimant should have undertaken part-time work from July 2007. He was assessed as capable of twelve hours’ work per week and likely to reach two-thirds of his pre-accident earning capacity in about three years, but was unlikely to return to full-time employment. Pain, suffering and loss of amenity were assessed at £32,500. Further argument was reserved on past and future loss of earnings.