Negligence
Factual Causation
1. The‘but-for test’
The ‘but for’ as a test of necessity, determined on the balance of probabilities.
- “Can it be said that ‘but for’ the defendant’s conduct, the claimant’s loss would
not have occurred?”
- “Would the claimant’s loss have occurred in any event, even without the
defendant’s conduct?” Yes → D will not have caused C’s loss
- In applying the “but for” test, the courts take into account not only existing causes
that might have produced the claimant’s loss, but also hypothetical causes that
might have produced the loss (McWilliams)
Establishing the relevant ‘counterfactual’ scenario.
• Barnett v Chelsea & Kensington Hospital Management Committee [1969]
Although the doctor had failed to examine the man, the man was beyond help
when he arrived at the hospital and would have died in any event. The doctor’s
breach of duty had not caused the man’s death → The doctor was not liable
• Performance Cars v Abrahams [1962]
D was only liable for the damage he had caused, not for the damage sustained
in the first collision → The first collision meant that the car was in need of a
re-spray prior to the incident involving the defendant
• McWilliams v Sir William Arrol Co [1962] (hypothetical act of the claimant)
- D were in breach of their statutory duty in failing to provide him with a
safety harness
- C had rarely used such a harness in the past → The defendants successfully
argued that this meant he would not have worn a harness even if one had been
provided → D were not liable because the man would probably have died in
any event
• Wilsher v Essex AHA [1988] (multiple alternative causes)
2. Causal problem scenarios (I): concurrent causes and the common sense
approach
- The causes in question occur more or less simultaneously, as opposed to one after
another
- Concurrent cause cases can be divided into 2 groups:
1) Indeterminate Cause: There is more than one defendant, but there is only one
“operative cause” of the claimant’s loss, it being unclear which of the defendants’
acts produced this cause. (Cook v Lewis; Summers v Tice)
2) Cumulative Cause: There is more than one “operative cause” of the claimant’s
loss, each produced by the act of a different defendant, but the problem is, these
causes have combined inextricably to produce the same damage
, • Summers v Tice (1948) (US decision) and Cook v Lewis [1951] (Canadian
decision)
In the absence of evidence from either defendant that he had not been
responsible for the bullet (negligent act), both defendants were held liable as
joint tortfeasors as each acted negligently.
• Fitzgerald v Lane [1987]
All three parties (the plaintiff, D1, D2) had been negligent and that, since it
was impossible to say that one of the parties was more or less to blame than
the other, the responsibility should be borne equally by all three. Therefore,
both defendants were held liable and the plaintiff was held contributory
negligent.
More complicated problems with the ‘but for’ test: difficulties of evidential proof
where there are either multiple cumulative causal agents or multiple defendants
responsible for exposing the claimant to the same causal agent.
To understand the differing natures of these causation problems, it is necessary to
distinguish between:
(i) divisible (dose-related/progressive) and indivisible harm (not dose-related/non-
progressive)
- Whether an injury is divisible or indivisible is a question of fact, and not of law
- Where there are causes concurrent in time, the likelihood is that a resulting injury
will be indivisible; but where causes are sequential in time, it is not likely that an
injury will be truly indivisible
(ii) ‘several liability’ (proportionate liability) and ‘joint and several liability’ (Civil
Liability (Contribution) Act 1978)
- Several Liability: Each of D1 D2 and D3 is liable for the whole of C’s damage. In
practice, this means that C is entitled to proceed against any one of D1 D2 or D3
individually for the whole of his damage; or C is entitled to sue each of D1 D2 and
D3, and each of those defendants will be liable for 100% of C’s damage (albeit that C
can only recover his damages once)
- Joint and Several liability: Each of D1, D2, and D3 is liable to C for the full amount
of C’s damage; Each D held liable for defined part of the harm at a value identified by
the court
3. Causal problem scenarios (II): multiple cumulative causes, divisible injuries
and the ‘material contribution to the harm’ approach
• Bonnington Castings Ltd v Wardlaw [1956]
- Because the disease was a divisible one, D liability should have been
proportionate (only liable for the extent to which the faulty exposure to the
dust made C’s harm worse)
- Court held D liable for the entirety of the harm → Much dispute to this
- You can argue the case both ways
1) All of the dust intermingled to bring about the entirety of the harm and you
can’t say for definite which part of the dust caused which bit of the harm,
therefore it is fine to hold D liable for the entirety of the harm
Factual Causation
1. The‘but-for test’
The ‘but for’ as a test of necessity, determined on the balance of probabilities.
- “Can it be said that ‘but for’ the defendant’s conduct, the claimant’s loss would
not have occurred?”
- “Would the claimant’s loss have occurred in any event, even without the
defendant’s conduct?” Yes → D will not have caused C’s loss
- In applying the “but for” test, the courts take into account not only existing causes
that might have produced the claimant’s loss, but also hypothetical causes that
might have produced the loss (McWilliams)
Establishing the relevant ‘counterfactual’ scenario.
• Barnett v Chelsea & Kensington Hospital Management Committee [1969]
Although the doctor had failed to examine the man, the man was beyond help
when he arrived at the hospital and would have died in any event. The doctor’s
breach of duty had not caused the man’s death → The doctor was not liable
• Performance Cars v Abrahams [1962]
D was only liable for the damage he had caused, not for the damage sustained
in the first collision → The first collision meant that the car was in need of a
re-spray prior to the incident involving the defendant
• McWilliams v Sir William Arrol Co [1962] (hypothetical act of the claimant)
- D were in breach of their statutory duty in failing to provide him with a
safety harness
- C had rarely used such a harness in the past → The defendants successfully
argued that this meant he would not have worn a harness even if one had been
provided → D were not liable because the man would probably have died in
any event
• Wilsher v Essex AHA [1988] (multiple alternative causes)
2. Causal problem scenarios (I): concurrent causes and the common sense
approach
- The causes in question occur more or less simultaneously, as opposed to one after
another
- Concurrent cause cases can be divided into 2 groups:
1) Indeterminate Cause: There is more than one defendant, but there is only one
“operative cause” of the claimant’s loss, it being unclear which of the defendants’
acts produced this cause. (Cook v Lewis; Summers v Tice)
2) Cumulative Cause: There is more than one “operative cause” of the claimant’s
loss, each produced by the act of a different defendant, but the problem is, these
causes have combined inextricably to produce the same damage
, • Summers v Tice (1948) (US decision) and Cook v Lewis [1951] (Canadian
decision)
In the absence of evidence from either defendant that he had not been
responsible for the bullet (negligent act), both defendants were held liable as
joint tortfeasors as each acted negligently.
• Fitzgerald v Lane [1987]
All three parties (the plaintiff, D1, D2) had been negligent and that, since it
was impossible to say that one of the parties was more or less to blame than
the other, the responsibility should be borne equally by all three. Therefore,
both defendants were held liable and the plaintiff was held contributory
negligent.
More complicated problems with the ‘but for’ test: difficulties of evidential proof
where there are either multiple cumulative causal agents or multiple defendants
responsible for exposing the claimant to the same causal agent.
To understand the differing natures of these causation problems, it is necessary to
distinguish between:
(i) divisible (dose-related/progressive) and indivisible harm (not dose-related/non-
progressive)
- Whether an injury is divisible or indivisible is a question of fact, and not of law
- Where there are causes concurrent in time, the likelihood is that a resulting injury
will be indivisible; but where causes are sequential in time, it is not likely that an
injury will be truly indivisible
(ii) ‘several liability’ (proportionate liability) and ‘joint and several liability’ (Civil
Liability (Contribution) Act 1978)
- Several Liability: Each of D1 D2 and D3 is liable for the whole of C’s damage. In
practice, this means that C is entitled to proceed against any one of D1 D2 or D3
individually for the whole of his damage; or C is entitled to sue each of D1 D2 and
D3, and each of those defendants will be liable for 100% of C’s damage (albeit that C
can only recover his damages once)
- Joint and Several liability: Each of D1, D2, and D3 is liable to C for the full amount
of C’s damage; Each D held liable for defined part of the harm at a value identified by
the court
3. Causal problem scenarios (II): multiple cumulative causes, divisible injuries
and the ‘material contribution to the harm’ approach
• Bonnington Castings Ltd v Wardlaw [1956]
- Because the disease was a divisible one, D liability should have been
proportionate (only liable for the extent to which the faulty exposure to the
dust made C’s harm worse)
- Court held D liable for the entirety of the harm → Much dispute to this
- You can argue the case both ways
1) All of the dust intermingled to bring about the entirety of the harm and you
can’t say for definite which part of the dust caused which bit of the harm,
therefore it is fine to hold D liable for the entirety of the harm
