Causation in Criminal Law
- teachlawhub
- Oct 5
- 5 min read
Updated: Oct 19
When trying to secure a conviction in criminal law, the prosecution must prove that the defendant’s actions caused the consequences to the victim, here they will establish the principle of causation. Causation is an essential principle that is used by the courts to establish whether the defendant’s actions were responsible for the consequences suffered by the victim. It is not enough to simply show that the defendant committed the actus reus (the physical element of the crime); it must also be proved that this act was carried out voluntarily, meaning the defendant acted of their own free will and that this then caused the consequences to occur.
Once this is established, the prosecution must demonstrate that the defendant’s actions were the ultimate cause of the injuries or death suffered by the victim. This principle is referred to as causation.
In order to prove causation, the courts apply and establish the following:
Factual causation,
Legal causation,
Any intervening acts that may have broken the chain of causation.
Lets explore each of these elements below:
Factual Causation
This is the first stage of establishing causation. Here, the court has to prove that the defendant was the factual cause of the injury or death to the victim. The courts will therefore apply the But For test. The but for test is but for the defendants’ actions would the consequence have occurred. If the answer is no, then the defendant is factually responsible for the outcome.
A key case that illustrates this is R v Pagett (1983), where the defendant used his pregnant girlfriend as a human shield during a confrontation with the police. The police returned fire, killing her. The court held that, but for the defendant’s actions, she would not have died, establishing factual causation.
In contrast, R v White (1910) shows how the but for test can fail. In this case, the defendant attempted to poison his mother’s drink, but she died of a heart attack before consuming it. The court ruled that the defendant’s conduct was not the factual cause of her death, as she would have died regardless of his actions.
Legal Causation
Once factual causation has been proven, the courts must establish legal causation. This involves considering whether the defendant’s conduct was a significant and operative cause of the harm.
In the case of R v Smith (1959), the victim was stabbed by the defendant and later received poor medical treatment at an army barracks. Despite the medical errors, the court ruled that the original stab wound was still the substantial and operating cause of death.
The law applies the de minimis principle in order to establish legal causation, this means that the defendant will be the legal cause of the consequences to the victim if the defendant’s act is more than a minimal cause of the result. It does not need to be the only or the main cause, but it must contribute in a way that is more than trivial.
In R v Kimsey (1996), the Court of Appeal held that the defendant’s driving need only be more than a minimal cause to the fatal crash.
These cases highlight how the courts ensure that defendants cannot escape liability simply because other factors also contributed to the victim’s death.
Intervening Acts (Novus Actus Interveniens)
The third stage of the test for causation considers whether the chain of causation has been broken by an intervening act, also known as a novus actus interveniens. For liability to remain, there must be a direct link between the defendant’s conduct and the consequence. If something happens afterwards that is sufficiently independent, it can break the chain and remove the defendant’s liability.
Intervening Act - Medical Treatment
Medical negligence does not usually break the chain of causation. The defendant will generally remain liable unless the treatment is so independent of their act and so potent in causing death that it renders the original injury insignificant.
R v Cheshire (1991) clarified that medical treatment must be so independent from the defendant’s original act and so potent in causing death that it makes the defendant’s contribution insignificant. In that case, the defendant had shot the victim, who later died from rare complications after medical treatment. The court ruled that the defendant’s actions remained a significant cause of death, as the medical treatment was not sufficiently independent or potent.
Medical treatment/negligence can break the chain of causation if it is considered to be palpably wrong (this means really bad).
For example, in R v Jordan (1956), the victim had almost recovered from stab wounds when doctors administered an antibiotic to which he was known to be allergic, causing his death. The treatment was described as palpably wrong and was held to have broken the chain of causation.
Furthermore, the act of turning off a life support machine, or withdrawing medical support will not break the chain of causation, this can be seen in the case of R v Malcherek (1981), it was held that doctors turning off a life support machine, or withdrawing medical treatment that leads to death, does not break the chain of causation. The original injuries inflicted by the defendant remain the substantial and operating cause.
Intervening Act - Actions of a Third Party
The actions of a third party can also be considered as a potential break in the chain of causation. For the chain to be broken, the third party’s actions must amount to an independent, free, deliberate, and informed intervention that overrides the defendant’s contribution.
R v Pagett (1983), the police returning fire at the defendant did not break the chain of causation. Their response was considered a foreseeable and reasonable reaction to the defendant’s conduct, and therefore the defendant remained responsible for the death.
The actions of a third party can break the chain of causation where the third party intended to make the situation/injuries worse.
In R v Rafferty (2007), Rafferty and his co-defendants attacked the victim. Rafferty left to go to the ATM, the co-defendants took the victim away after the initial attack and drowned him. Their actions were held to have broken the chain of causation in relation to the original attacker, as they were independent and deliberate.
Intervening Act - Victim’s Own Actions
The victim’s own actions may also break the chain of causation, but only where they are so unexpected that no reasonable person could have foreseen them. This is known as the daftness test. If the victim’s response is proportionate and reasonably foreseeable, the defendant remains liable.
For example, in R v Roberts (1971), the victim jumped out of a moving car to escape the defendant’s unwanted sexual advances. Her reaction was deemed reasonable and foreseeable, so the chain of causation was not broken and the defendant was liable for her injuries.
The Thin Skull/Egg Shell Skull Rule
An important limitation to the principle of causation is the Thin Skull Rule, also known as the egg shell skull rule. This rule states that the defendant must take the victim as they find them.
In other words, if the victim has a unknown weakness or condition that makes the injury more serious than expected, the defendant is still liable for the full extent of the harm.
This principle was applied in R v Blaue (1975), where the defendant stabbed a woman who refused a life saving blood transfusion on religious grounds. She later died, and the defendant argued that her refusal had broken the chain of causation. The court rejected this, holding that the defendant had to take the victim as he found her, including her religious beliefs.
Conclusion
The principle of causation ensures fairness and responsibility in criminal law by linking the defendant’s actions directly to the harm caused. The tests of factual causation, legal causation, and intervening acts provide a structured approach to determine liability, while the Thin Skull Rule ensures that defendants cannot escape responsibility simply because the victim is more vulnerable than anticipated. Together, these rules ensure that criminal responsibility is imposed only where the defendant’s conduct has made a real, significant, and continuing contribution to the harmful outcome.
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