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causation


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N.

The relationship between an act and the consequences it produces. It is one of the elements that must be proved before an accused can be convicted of a crime in which the effect of the act is part of the definition of the crime (e.g. murder). Whatever other causes may have effected the bringing about of the actus reus, it needs to be shown that the defendant's behaviour did, in a significant way, contribute to the actus reus. In R v White [1910] 2 KB 124, White gave poison to his mother who died. However, medical evidence proved that the mother had died from a heart attack and that the poison was in no way connected to the death. Therefore the defendant's behaviour did not contribute in any way to the resulting death.

Causation is a question of both 1) fact and 2) law and in both cases this is a question for the jury to decide:1) Factual causation: it must be shown that, “but for” the defendant's act, the event would not have occurred. The act must be a causa sine qua non (“cause without which”) of the event. a test sometimes known as the “but for” test.2) Legal causation: the defendant's act must be an operative and substantial cause of the consequence. His act need not be the sole cause, but must make a significant and not trivial (de minimis non curat lex) contribution to the result. For example, if a doctor takes a blood sample from a patient who has been stabbed and is dying the taking of the blood will weaken the patient, but the doctor's role in the patient's death is minimal and causally insignificant.Sometimes a new act or event (novus actus (or nova causa) interveniens) may break the legal chain of causation and relieve the defendant of responsibility. The chain of causation between the defendant's act and the resulting consequences will be broken if another unforeseeable act occurs and if “the second cause is so overwhelming as to make the original [act] merely part of the history” (Lord Parker CJ in R v Smith [1959] 2 QB 35 at 42-43).

1) Factual causation: it must be shown that, “but for” the defendant's act, the event would not have occurred. The act must be a causa sine qua non (“cause without which”) of the event. a test sometimes known as the “but for” test.

2) Legal causation: the defendant's act must be an operative and substantial cause of the consequence. His act need not be the sole cause, but must make a significant and not trivial (de minimis non curat lex) contribution to the result. For example, if a doctor takes a blood sample from a patient who has been stabbed and is dying the taking of the blood will weaken the patient, but the doctor's role in the patient's death is minimal and causally insignificant.

In tort it must be established that the defendant's tortious conduct caused or materially contributed to the damage to the claimant before the defendant can be found liable for that damage. In order to determine factual causation, courts adopt the same “but for” test used in criminal cases: “but for” the defendant's tortious conduct, would the claimant's loss have occurred (Barnett v Chelsea and Kensington Hospital Management Committee [1969] 1 QB 428)? However, this test is inadequate for cases of concurrent or cumulative causes, where the actions of two or more tortfeasors are each sufficient to produce the damage. Where there is more than one possible cause there are several tests that may be applied. For example, did the defendant's negligence materially increase the risk of injury (Mc Ghee v National Coal Board [1973] 1 WLR 1)? Similarly, was the defendant's breach of duty a material cause of the injury? One of five causes will not suffice to establish liability (Wilsher v Essex Area Health Authority [1988] AC 1074). In order for causation to be established on the balance of probabilities, it requires at least a 51% chance that the defendant's actions caused the damage (Hotson v East Berkshire Health Authority [1987] AC 750).

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