Within tort law there are two types of causation: factual causation and legal causation (also known as remoteness). This lecture focuses on factual causation.

Factual causation can best be summarised by the but for test that asks the following question:Would the damage have occurred ‘but for’ the action/omission of the defendant? This test originates from the case of Barnett v Chelsea & Kensington Hospital [1969] and like other elements of tort law is measured on the balance of probabilities. This normally involves an interrogation of the facts of individual cases.

There are some circumstances that require a closer look at the 'but for' test such as where there are multiple causes. Here some may be innocent and some may be tortious as in the case of McGhee v National Coal Board [1973]. In that case Lord Wilberforce stated that “it is a sound principle that where a person has, by breach of a duty of care, created a risk, and injury occurs within the area of that risk, the loss should be borne by him unless he shows that it had some other cause” essentially reversing the burden of proof. This was heavily criticised in Wilsher v Essex AHA [1988] by Lord Bridge but there still may be some circumstances where it is fair to reverse the burden of proof onto the defendant.

The same thing applies to where there are multiple defendants and a strict application of the but for test would mean neither defendant would be liable: Fitzgerald v Lane [1987]. This sits alongside the general principle of liability in solidum whereby all defendants may be liable for the damage as a whole.

Mesothelioma cases have also posed problems for the courts in the past. The main case of Fairchild v Glenhaven Funeral Services [2003] allowed claimants to be successful despite the problematic questions of causation that arose. This was taken further in Barker v Corus UK Ltd [2006] where it was decided that exposure to the risk could be considered damage in its own right. Such cases were eventually legislated on via section 3 of the Compensation Act 2006 that restored the principle of in solidum liability.

Supervening or overtaking causes can also pose a problem as the law of causation can either act in an unfair way against a defendant (as in Baker v Willoughby [1970]) or mean that a claimant does not receive sufficient compensation. This was addressed in Jobling v Associated Dairies [1982] where the damages were reduced because of the supervening cause.

This leads on to questions of loss of chance.which originally comes from the United States of America case Hicks v U.S. [1966] where it was held that “if there was any substantial possibility of survival and the defendant has destroyed it, he is answerable.” this often applies in cases of medical negligence but it must be remembered that under the balance of probabilities the chances of survival must be greater than 50% in the first instance.