Hardwicke Building's Robert Leonard has had a recent success in the Court of Appeal in Environment Agency v Ellis  EWCA Civ 1117 regarding causation in single accident cases. The Court of Appeal reaffirmed the conventional approach to causation despite the defendant’s attempt to introduce principles of apportionment between competing causes, as applied in certain industrial disease cases. The claimant had suffered an injury at work due to the negligence of the defendant. The Judge had awarded the claimant 90% of his damages. The Defendant's appeal sought to reduce this to 40% on the basis of medical evidence as to the degree to which the accident and various other causes had contributed to the claimant's condition. The claimant cross appealed seeking 100% of damages on the basis that the evidence showed that but for the index accident the other causes would have been incidental. The 'but for' test prevailed, the appeal failed and the cross appeal succeeded.