Tort Law, negligence-factual causation

but-for test

It's a test asking: But for the defendant's negligence, would the claimant have suffered the injury? If yes, causation fails; if no, causation is established.

Barnett v Chelsea & Kensington Hospital [1969]

A man was negligently turned away from A&E and later died. But he would have died even with treatment, so no factual causation was found.

Principle from Barnett v Chelsea & Kensington Hospital

That a defendant can be negligent, but if their actions did not cause the harm (but-for test fails), there is no liability.

Robbins v LB Bexley [2013]

The court must consider what the defendant would have done if not negligent. If they would have avoided the harm, causation is met.

divisible injury

An injury where the contribution of multiple causes can be separated. Defendants are liable only for their contribution.

Bonnington Castings v Wardlaw [1956]

The claimant's disease was caused by both negligent and non-negligent dust. The court found liability as negligent dust made a material contribution.

Holtby v Brigham & Cowan [2000]

Each employer is only liable for their share of asbestos exposure causing disease—a proportional approach to divisible injury.

material contribution to risk doctrine

Used when it's scientifically impossible to prove causation, but the defendant materially increased the risk of harm.

McGhee v National Coal Board [1973]

The claimant got dermatitis after exposure to brick dust. It was unclear which exposure caused it, but the employer was liable for increasing the risk.

Fairchild v Glenhaven [2003]

Several employers exposed the claimant to asbestos. It was unknown which one caused mesothelioma, but all were liable for increasing risk.

Barker v Corus [2006]

When Fairchild applies, each employer is only proportionally liable for the risk they contributed—unless it's a mesothelioma case (reversed by statute).

Wilsher v Essex AHA [1988]

Because the injury could have been caused by multiple unrelated agents, not a single agent—so Fairchild's special rule didn't apply.

loss of a chance

It's a claim that the defendant's negligence reduced the claimant's chance of a better outcome—but it's not generally allowed in personal injury.

Hotson v East Berkshire HA [1987]

A 25% chance of avoiding injury was lost due to misdiagnosis. Because it was under 50%, no causation was found—claim failed.

Gregg v Scott [2005]

A doctor's delay reduced cancer survival chances from 42% to 25%. Since the original chance was under 50%, no damages were awarded.

Lady Hale's concern about loss of a chance

It would undermine the but-for test and create confusing distinctions between full recovery and partial chance-based recovery.

compensability of loss of a chance

In pure economic loss cases (e.g., missed business deals), not in personal injury.

Allied Maples v Simmons & Simmons [1995]

If outcome depends on the claimant, prove 51% chance. If it depends on a third party, damages can reflect lost chance as a percentage.