CAUSATION

1. Factual Causation – The “But For” Test

The claimant must prove the damage would not have occurred but for the defendant’s breach (Barnett v Chelsea & Kensington HMC [1969]). If the harm would have happened anyway, causation fails (McWilliams v Sir William Arrol [1962]). The test is applied on the balance of probabilities (>50%).

2. Break in the Chain of Causation (Novus Actus Interveniens)

A new intervening act may break the chain if it is independent and unforeseeable.

• Third-Party Acts → Foreseeable acts do not break the chain; grossly negligent or unforeseeable acts may do so (Lamb v Camden LBC [1981]; Knightley v Johns [1982]).

• Claimant’s Own Acts → Unreasonable conduct may break the chain; foreseeable reactions usually amount only to contributory negligence (McKew v Holland [1969]; Spencer v Wincanton Holdings [2009]).

• Acts of Nature → Unforeseeable natural events may break causation; foreseeable consequences will not.

3. Loss of Chance

Causation must be proven on the balance of probabilities; loss of a mere possibility is insufficient in personal injury claims (Hotson v East Berkshire AHA [1987]; Gregg v Scott [2005]).

4. Legal Causation – Remoteness of Damage

Even where factual causation is established, the damage must not be too remote.

• Foreseeable Type of Harm → The defendant is liable only for damage of a reasonably foreseeable kind, not the exact sequence of events (The Wagon Mound (No 1) [1961]; Hughes v Lord Advocate [1963]).

• Extent of Damage → The full extent of injury is recoverable even if unusually severe (Jolley v Sutton LBC [2000]).

• Thin Skull Rule → The defendant must take the claimant as found; unusual vulnerability does not limit liability (Smith v Leech Brain [1962]).