Factual Causation

Factual Causation, or the Causa Sine Qua Non is a required element in number of types of cases.

Unintentional Delicts
In addition to showing that the defender had a duty of care, and breached the duty of care, the persuer must show factual causation - that "but for" the defenders actions, the loss would not have occurred.

This requirement lies purely with the persuer, the defender does not have to show an alternative theory.

This test, whilst simple, can lead to some seemingly disappointing results. In Barnett v Chelsea and Kensington Hospital a man drunk tea laced with poison, although he visited the hospital it was not correctly picked up an due was instead told to see his own doctor the following day. Although the doctor he saw had been negligent in not detecting the poison, as the doctor would not have been able to cure it anyway factual causation was not found.

In Kay's Tutor v Ayrshire and Arran Health Board a child suffering meningitis was given a massive overdose of penicillin, and although mostly recovered suffered from deafness. Although there was a clear breach of the duty of care, the persuer could not prove that the deadfness was as a result of the overdose (instead it is a common result of a meningitis infection), as such causation was not found.

In Bolitho v City and Hackney Health Authority, a doctor was negligent in failing to attend a child, but as the only course of medical assistance that could have saved the child was one that was not recommended my the majority of medical opinion, this case too failed. In Gregg v Scott the threshold for this was set at a 50% chance of success had the omission not occurred for causation to be found.

Where two or more potential causes coexist concurrently, the cause can be determined to be both items, such as in Wardlow v Bonnington Castings ltd Dust from one situation which was inadequately controlled, and dust from another with was not technically possible to control contributed to Wardlow's respiratory injury. As one of the sources was not technically controllable, if this was the cause sine qua non there could ordinarily be no claim. However as both materially contributed to the injury, both were held together as the cause and thus actionable. McGhee v National Coal Board extended this further to consecutive acts as well where it materially contributes to the injury.

In Fairchild v Glenhaven the above concept was taken further, where an employee had worked at two different employers with asbestos (and developed respiratory problems), but could not prove which one directly had been the causa sine qua non of his respiratory illness, the "but for" test was suspended, with both employers materially contributing towards the illness which is recognised to come from asbestos both could be liable.