Causation

It is obvious that in order to blame an individual for their actions, there must be some link between the action and the damage caused: we cannot blame someone completely unconnected with the damage. This link is what causation seeks to establish. Direct causation can be established by using the 'but-for' test. But for, or put otherwise, except forthe action of the defendant, could the harm have occurred? Factual (i.e. direct) causation is proved when the answer is, yes, the damage could only have because of the Defendant.

However, while the basic test is a simple one, the situation becomes more complex when there are multiple causes of an injury, or where an action intervenes between the Defendant's action and the ultimate damage. Thus a second type of causation exists in these more complex situations, known as legal causation or remoteness. In those cases, the Defendant may have been the direct (factual) cause of the accident but they will not be held liable since the court considers that the injury was too remote. Cases involving legal causation remain difficult to decipher in some situations though the general principles are clear.

But-For Test

The but-for test is the basic causation test in negligence claims. The object of the test is to evaluate whether the Claimant's injury would have occurred without the defendant's actions. The question is: can we suggest that the injury would not have occurred to the Claimant except for the action of the Defendant. An important preliminary point to note is that the cause of the injury is to be judged on a balance of probabilities i.e. what is more likely. Thus, as long as it is more likely than not (even if only 51% vs. 49%) that but-for the Defendant's action the injury would not have occurred, it will be held that the but-for test is satisfied. The idea of how much an action caused an injury is usually best explained in percentages, thus the cases will often speak in these terms.

An example of the but-for test is Barnett v Chelsea & Kensington Hospital [1969] 1 QB 428. A nightwatchman had gone to the Defendant's hospital after drinking some tea and becoming ill. One of the doctors told the nightwatchman to go home and consult his own doctor. A few hours later the man died from arsenic poisoning. The judge said that it was negligent to send him away but questioned whether the negligence caused the death: but-for the Defendant sending the man away, would he have lived? The medical evidence was that the nightwatchman was at the hospital by 8.10am, he could have been admitted by 11am and it was possible that a diagnosis could have been made by 12.30pm. However, if the nightwatchman was not treated before 12pm, the chances of his survival were not good. The court refused to impose liability on the basis that, by the time a diagnosis and treatment could be administered, it would have been too late to save the man's life. Thus it could not be said that only because of the negligence (but-for the negligence) the man would have survived as even if there had been no negligence he would have died anyway.

So, the basic principles are:

•  There must but-for causation, or in other words, only because of the negligence the Claimant suffered injury,

•  The court will make decisions of fact on a balance of probabilities.

•  Thus, the court in Barnett found that the watchman probably wouldn't have survived even if there was no negligence; it did not find that he definitely wouldn't have survived, simply that the chance of him not surviving was higher than 50%.

The but-for test is simple and therefore very useful. However, it becomes more problematic in cases where there is a lot of uncertainty as to how much the defendant contributed. Thus, what happens in situations where the court cannot say that the Defendant caused the injury on a balance of probabilities?

In Hotson v East Berkshire Area Health Authority [1987] AC 750, the 13 yr old Claimant fell from a tree and broke his hip. He was taken to hospital where they failed to diagnose the broken hip and sent him home. He returned several days later complaining of pain and the correct diagnosis was made. However, some time later his injury turned into a condition called avascular necrosis. The court found that there was a 75% chance that the avascular necrosis would have developed even if there had been no negligence. The judge at first instance awarded the Claimant 25% of the damages he would have received had it been proved that the avascular necrosis was entirely the Defendant's fault (the Court of Appeal upheld this). The House of Lords, however, found for the Defendant on the grounds that the Claimant could not