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Tort | Negligence

Damage: Causation

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  • causation: establishing that defendant's (D) negligence caused claimant's (C) harm, both factually & in law

Factual causation: the 'but for' test

  • factual causation often referred to as the chain of causation
  • determined by but for test


    • Victim (V) was negligently sent home untreated from D's hospital & died of arsenic poisoning a few hours later
    • medical evidence suggested V would probably have died, even if proper treatment had been given promptly


    • did D's negligence cause V's death?


    • D 's negligence did not cause V's death, the arsenic was the cause
    • established but for test: But for D's breach of duty, would the harm to C have occurred? yes: D is not factually liable, no: factual causation is satisfied

    Mc Williams (Cummings) v Arrol & Co [1962] 1 WLR 295


    • V fell to his death while working for D at 70ft
    • D did not provide safety harness (despite statutory duty) but was evidence V would not have worn even if provided


    • did D's breach of duty cause V's death?


    • House of Lords: D not liable, factual causation not satisfied
    • but for D's breach V would still have died as would not have worn the harness

Factual causation: proof

  • C must prove on the balance of probabilities their harm was caused by D's breach of duty


    • P fell from tree & his injuries were wrongly treated at D's hospital, P left permanently disabled
    • D admitted negligence but denied liability, evidence showed 75% chance that P's condition would not have been improved by correct treatment


    • did D's breach of duty cause P's injuries?


    • D not liable, factual causation not satisfied
    • only 25% chance negligent medical treatment affected C's prognosis, so did not satisfy balance of probabilities
    • all or nothing approach: require more than 50% chance

Factual causation: clinical negligence

  • clinical negligence claims may lead to complex causation issues


    • P received negligent treatment at D's hospital & was left blind
    • there were 4 other different, independent possible causes of his blindness, each alone could have been the cause


    • did D's breach of duty cause P's injuries?


    • P could not show on a balance of probabilities D's negligence caused the damage, only 20% chance
    • House of Lords ordered retrial on issue of causation


    • V suffered serious brain damage following respiratory failure & died at D's hospital, doctor did not attend (due to technology failure) until after V died
    • P argued doctor should have attended & carried out a specific procedure, which would have saved V's life
    • doctor testified she would not have carried out procedure even if she had attended & her evidence was backed by medical professionals


    • how could did the but for test apply?


    • D's negligence was based an omission to act, therefore, the court had to consider but for test in hypothetical situation
  • courts are cautious about finding against medical professionals for policy reasons: may affect willingness to treat patients or try pioneering new procedures & cost of medical care would increase due to higher insurance premiums

Factual causation: multiple causes

  • if several possible alternative causes C must show that harm was caused by D's breach (as in Wilsher v Essex Area Health Authority [1988])
  • however, cases often involve harm which may have been caused by a combination of a number of factors

Material contribution approach

  • material contribution approach used to help determine causation where multiple causes contributed to C's harm
    • P contracted disease caused by exposure to dust from pneumatic hammer and swing grinders
    • D in breach of statutory duty to maintain swing grinders, so only liable in Negligence if they were the cause of P's disease
    • what was the cause of P's disease?
    • factual causation established: on the balance of probabilities dust from swing grinders had materially contributed to causing P's disease
    • Lord Reid: .. [the plaintiff] must make it appear at least that on a balance of probabilities the breach of duty caused or materially contributed to his injury...
    • Waller LJ: .. In a case where medical science cannot establish the probability that 'but for' an act of negligence the injury would not have happened but can establish that the contribution of the negligent cause was more than negligible, the 'but for' test is modified, and the claimant will succeed...
    • P contracted dermatitis due to exposure to dust, when cleaning brick kilns for D
    • evidence suggested only way to avoid was thorough washing immediately after contact & D negligently did not provide washing facilities on site
    • however, evidence did not establish whether lack of washing (D was liable for) or more generally exposure (D not liable for) was the cause


    • was sufficient causation proved?
    • P could not prove D caused his dermatitis under strict all or nothing approach(Hotson v East Berkshire Area Health Authority [1987])
    • P also unable to prove D's failure to provide onsite washing facilities materially contributed to his dermatitis (Bonnington Castings Ltd v Wardlaw [1956])
    • House of Lords:D's failure to provide onsite washing facilities was a material contribution to the risk of injury & sufficient to prove factual causation
  • courts have modified but for test, C must establish D's negligence either: materially contributed to the harm (Bonnington Castings Ltd v Wardlaw [1956]) or materially contributed to the risk of harm (McGhee v National Coal Board [1973])
  • in Wilsher v Essex Area Health Authority [1988], D only responsible for one of possible risk factors & it could not be shown that this increased risk, so C still unable to satisfy factual causation

Divisible injury

  • issue arises: to what extent is D who either materially contributed to C's harm or risk of C's harm liable for damages?

    Holtby v Brigham & Cowan (Hull) Ltd [2000] 3 All ER 421

    • C suffered asbestosis due to exposure to asbestos at work (cumulative condition, which got progressively worse the longer exposure continued)
    • over several years, C carried out same work for several employers, including D
    • to what extent was D liable?
    • C succeeded in demonstrating D's negligence materially contributed to disease, so D responsible for proportion of harm
    • damages apportioned between D & other employers (the tortfeasors) according to time C worked for each
    • C must make claim against all tortfeasors to recover full damages

Indivisible injury

  • in some cases more than one D has made a material contribution to C's harm but it is not divisible (eg. single injury in a road traffic accident)

    • S1(1): Ds are jointly & severally liable for the full damages owed to C
    • S2(1): courts can apportion liability for damages between Ds according to their share of responsibility for harm caused

Recent developments

  • recent decision criticised for weakening test for factual causation: leaving employers & insurers vulnerable to large claims, but arguably provides just recourse for Cs who have suffered serious harm
    • Cs had developed mesothelioma (cancer) caused by exposure to asbestos while working for several employers, Ds were some but not all of the employers
    • medical evidence failed to show which employer responsible for the exposure which led to the cancer, so each D argued but for test was not satisfied
    • could Ds be held responsible?
    • Court of Appeal: lack of medical certainty meant factual causation not proved
    • House of Lords: approved approach in McGhee v National Coal Board [1973], finding Ds materially contributed to risk of Cs contracting cancer & mesothelioma was an indivisible injury & therefore, Ds were jointly & severally liable
  • another controversial decision followed, appearing to retract scope of Fairchild v Glenhaven Funeral Services Ltd [2003]
    • Cs contracted mesothelioma working for several employers, D only one still trading
    • D argued unfair to impose joint & several liability when their breach only contributed to risk of harm & that liability should be proportionate (to extent to which they contributed to risk: time they employed Cs)
    • could D be held jointly and severally liable?
    • House of Lords (majority): liability for mesothelioma under Fairchild v Glenhaven Funeral Services Ltd [2003] , was for risk of harm & therefore D's liability should be proportionate
    • although mesothelioma was an indivisible injury, the risk was divisible & should be reflected in D's liability
  • Barker v Corus [2006] heavily criticised for limiting Cs ability to receive damages, so Parliament passed Compensation Act 2006 (effectively reversed decision for Cs suffering mesothelioma)
  • unclear whether decision will be followed in cases where causation is based on material contribution to risk of other harm

Factual causation: loss of chance

  • courts must focus on outcome of events not damage which occurred if C argues D's breach caused a loss of chance, rather than the harm
  • Hotson v East Berkshire Area Health Authority [1987], House of Lords used all or nothing approach but refused to rule out successful loss of chance cases in different circumstances


    • C had a lump under his arm which D negligently diagnosed as benign, it was untreated & the cancer spread
    • medical evidence suggested if misdiagnosis not have occurred C would have had 45% chance of recovery


    • was D liable for C's loss of chance?


    • House of Lords (majority): applied Hotson v East Berkshire Area Health Authority [1987] & confirmed all or nothing approach

Factual causation: multiple injuries

  • if C has already suffered harm, a subsequent D is only liable to extent that he makes C's harm worse

    Performance Cars v Abraham [1962] 1 QB 33


    • D negligently hit C's car & car required re-spray
    • 2 weeks earlier C's car had been hit by another negligent driver & initial incident meant car needed re-spraying prior to incident involving D


    • could D be liable for the damage?


    • Court of Appeal: D not liable for cost re-spray, because D's breach not caused the need for the re-spray
  • similar issues can arise in relation to personal injuries


    • C suffered physical injuries after an assault at work, which his employer (D1) had negligently failed to protect him from
    • subsequently C was left blind in one eye after receiving negligent treatment at D2's hospital
    • furthermore C suffered severe continuing psychiatric injury


    • to what extent was each D liable?


    • D1 was solely responsible for initial injuries & loss of wages resulting from the attack
    • D2 was solely responsible for the blindness
    • D1 & D2 were liable for the psychiatric injury, which was found to be divisible (on the basis of medicial evidence) & therefore, the damages were apportioned between D1 & D2

Legal causation: intervening acts

  • both factual & legal causation must be proved to make a claim in Negligence
  • chain of causation: D's breach of duty must have caused or materially contributed to C's injury or loss
  • chain may be broken by an intervening event: extrinsic events (nova causa interveniens) may occur or independent act of someone other than D (novus actus interveniens)

Third party

  • an intervening act of a third party may break chain of causation
  • third party act will not break chain of causation if D is under legal duty to prevent that act

    Stansbie v Troman [1948] 2 KB 48

    • C had property stolen from her house when D left it unoccupied & unlocked
    • D under a duty to secure if he left
    • did the intervening act break the chain of causation?
    • chain of causation not broken: actions of the thief was the very reason D under a duty to secure the property
  • third party act will break chain of causation if it is an unforeseeable consequence of D's own negligence
    • D was driving negligently & his car turned over near exit from one-way tunnel
    • police officer arrived at scene & negligently directed P to drive back up tunnel
    • P collided with oncoming vehicle & was injured
    • did the intervening act break the chain of causation?
    • chain of causation was broken: foreseeable the police would attend but gross negligence of officer was not foreseeable
    • negligent act of third party more likely to break chain of causation, but not definitely because some errors of judgment are foreseeable
    • Stephenson LJ: .. mistakes and mischances are to be expected...
  • question of foreseeability, even if third party was negligent will be decided on facts of each case

    Rouse v Squires [1973] QB 889

    • D's careless driving resulted in his lorry skidding & blocking two lanes of the motorway
    • another lorry driver(also driving negligently) failed to see blockage soon enough & killed P's husband, who had stopped to help D
    • did the intervening act break the chain of causation?
    • Court of Appeal: chain of causation not broken: reasonably foreseeable other drivers may arrive at scene too fast to stop
    • D & second driver made material contribution to the indivisible injury, under Civil Liability (Contribution) Act 1978 liability apportioned between them
  • an instinctive intervention may not break chain of causation, if it is a foreseeable reaction
    • D threw a lighted squib into a crowded market, two other individuals picked squib up & threw it away from themselves
    • squib eventually exploded in front of P, who lost his eye
    • did the intervening act break the chain of causation?
    • chain of causation not broken: third parties acted instinctively to danger posed by D's act
    • De Grey CJ: .. any innocent person removing the danger from himself to another is justifiable... acting under a compulsive necessity for their own safety and self-preservation...


  • C's own act may break chain of causation, if he acts unreasonably
    • P injured his leg at work, due to D's negligence
    • a few days later, P was descending steep steps without a handrail, he lost control of his leg & fell, severely fracturing his ankle
    • did P's intervening act break the chain of causation?
    • chain of causation broken: P took an unreasonable risk
    • Lord Reid: .. if the injured man acts unreasonably he cannot hold the defender liable for injury caused by his own unreasonable conduct. His unreasonable conduct is novus actus interveniens. T he chain of causation has been broken and what follows must be regarded as caused by his own conduct...
  • C's carelessness may not always so unreasonable as to break chain of causation but may amount to contributory negligence
    • C was injured at work resulting in his leg being amputated, D was liable was for this injury
    • several months later, C had an accident (trying to use his new prosthesis) & he was permanently confined to a wheelchair
    • did C's intervening act break the chain of causation?
    • chain of causation not broken: but damages reduced as contributory negligence was accepted as partial defence
    • Lord Sedley: .. Like the amputation, the fall was... an unexpected but real consequence of the original accident, albeit one to which [the claimant's] own misjudgement contributed...
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