Theory of Causation

1. Meaning and Concept of Causation

Why causation matters

Every result crime, from murder under Section 103 BNS to cheating under Section 316 BNS, requires that the prohibited result be caused by the accused's conduct. If A fires a gun at B and B, entirely unrelated to the shot, dies of a heart attack the same evening, A cannot be convicted of murder. Causation is the doctrine that separates these two situations. It asks whether the actor's conduct is legally responsible for the result the law prohibits.

| The central ideaCausation is the logical and legal link between the accused's act (or omission) and the harmful consequence. Where the link is broken or attenuated, criminal liability for the consequence falls away, even where the act was culpable and the mens rea was present. | | --- |

The doctrine operates at two levels. The first is factual: did the act, as a matter of physical fact, produce the result. The second is legal: even if it did, is the connection close enough to attach blame. Both must be answered in the affirmative before the accused can be held liable for the result.

Causation as the link between act and result

Salmond described causation as the connection between an event and its consequences, without which no responsibility can be assigned. Kenny put the matter differently: an act is a cause of an event if, but for the act, the event would not have occurred, and if the act contributes substantially to it. Both formulations pull in the same direction. The act must have made a difference, and the difference must have been substantial.

2. Factual Causation: The But-For Test

The sine qua non principle

Factual causation is tested by the classical but-for rule, also called the sine qua non rule. Would the result have occurred but for the accused's act. If the answer is no, the act is a factual cause. If the answer is yes (the result would have occurred anyway), the act is not a factual cause.

Sine qua non: without which not.

| 📖 R. v. White, [1910] 2 KB 124The accused put potassium cyanide into his mother's drink intending to kill her. The mother was found dead beside a partially drunk glass, but the medical evidence showed she had died of a heart attack, not poisoning, and had drunk too little to be affected. The English Court of Criminal Appeal held that the accused was not guilty of murder, because the poisoning was not the factual cause of death. But he was guilty of attempted murder. Rule: without factual causation, there is no completed offence, however grave the intent. | | --- |

Limits of the but-for test

The but-for test works for most cases but breaks down at the margins. Two situations expose its limits.

• Multiple sufficient causes. Where two independent acts each would have been sufficient to cause the result, a strict but-for test would acquit both actors. Suppose A and B, acting independently, each fire a fatal shot at V at the same moment. Neither can say his shot was the but-for cause, because V would have died from the other. The law solves this by treating each act as a substantial cause of the result.
• Acceleration cases. Where the act accelerates a death that was going to occur, but-for causation is not strictly satisfied. Indian law treats acceleration as sufficient. In Rewaram v. State of Madhya Pradesh, discussed below, the Supreme Court held that hastening the death of a person already destined to die from illness is causing death for the purposes of Section 299 IPC (now Section 100 BNS).

3. Legal Causation: The Proximate Cause

Even where factual causation is established, the law will not fasten liability for every downstream consequence. Legal causation, also called proximate causation, is a set of principles the courts use to keep responsibility within reasonable limits. The classical formulation from Lord Wright in the tort case of The Oropesa, [1943] P 32, extends to criminal law: the conduct must not merely be a cause, it must be a proximate cause, and not too remote a cause.

| The two limbs of causationFactual limb: was the act a sine qua non, a cause without which the result would not have occurred.Legal limb: was the act a substantial and reasonably direct cause, not too remote or attenuated to justify criminal liability. | | --- |

Reasonable foreseeability

A useful guiding thread through the doctrine is the question of foreseeability. If the result was a reasonably foreseeable consequence of the act, causation is usually made out. If the result was so freakish or unusual that no reasonable actor could have anticipated it, causation is often broken. Foreseeability is not a standalone test; it is a factor to which the courts return again and again when applying the substantial cause and novus actus doctrines.

4. Tests and Doctrines of Causation

Substantial cause test

The accused's act must be a substantial and operating cause of the result. It need not be the sole cause, and it need not be the immediate cause, but it must be more than trivial. The doctrine is best associated with the English decision of R. v. Smith, though it has been applied by Indian courts in similar terms.

| **📖 R. v. Smith, [1959] 2 QB 35 (Courts-Martial Appeal)**A soldier stabbed a fellow soldier during a barracks fight. The victim was dropped twice on his way to the medical station and received treatment that was later shown to be inappropriate. He died. On appeal, the Court held that the stab wound remained a substantial and operating cause of death, notwithstanding the poor medical treatment. Only where the second cause is so overwhelming as to make the original wound merely part of the history could the chain be regarded as broken. Rule: bad medical treatment does not break the chain unless it is palpably wrong and independently sufficient. | | --- |

| 📖 R. v. Jordan, (1956) 40 Cr App R 152The victim of a stab wound was recovering in hospital when he was given a drug to which he was known to be intolerant, and then large quantities of intravenous fluids. He died. The Court of Criminal Appeal held that the medical treatment was palpably wrong and had become the sole cause of death, breaking the chain from the original wound. Rule: medical treatment can break the chain, but only when it is palpably wrong. Smith and Jordan mark the outer limits of medical intervention as novus actus. | | --- |

Novus actus interveniens: the intervening act

Latin for a new intervening act, novus actus interveniens is the doctrinal name for an event that breaks the chain of causation between the accused's act and the result. Three kinds of intervening events are commonly discussed: acts of a third party, acts of the victim, and acts of nature.

| When an intervening act breaks the chainIt must be an independent, free and voluntary act by a third party, or an unforeseeable act by the victim or nature.It must be so overwhelming that the original act is reduced to part of the history and not the operating cause.The result must be unforeseeable at the time of the original act. | | --- |

| 📖 R. v. Pagett, (1983) 76 Cr App R 279The accused, resisting arrest, held his pregnant girlfriend in front of him as a human shield and fired at armed police officers. The police returned fire and killed the girlfriend. The Court held that the accused caused her death. The police response was reasonable and foreseeable, and it did not amount to a novus actus interveniens. Rule: a reasonable response by lawful authority to the accused's own wrongful act does not break the chain. | | --- |

| 📖 R. v. Roberts, (1971) 56 Cr App R 95A woman jumped from a moving car to escape sexual advances by the driver, and was injured. The Court of Appeal held that her act did not break the chain. Her response, however extreme, was reasonably foreseeable as a consequence of the accused's conduct. Rule: an act by the victim that is a reasonably foreseeable response to the accused's conduct is not a novus actus. | | --- |

| 📖 Joginder Singh v. State of Punjab, (1979) 4 SCC 401The deceased jumped from a wall while being chased by the accused and their companions in a fight. He sustained head injuries and died. The Supreme Court held that the death was not attributable to the accused. His act of jumping was an independent act and there was no evidence of any act of the accused that caused injury leading directly to the death. Rule: an independent act of the victim, disconnected from any wrong caused by the accused, breaks the chain of causation. | | --- |

The thin skull rule (egg-shell skull)

The thin skull rule, imported from tort law and applied in criminal cases, provides that the accused must take his victim as he finds him. If the victim has an unusual physical or mental vulnerability (a thin skull, a weak heart, a religious belief that leads him to refuse treatment), and this vulnerability aggravates or hastens the harm, the accused remains liable for the whole of it. The accused cannot say the victim should have been more robust.

| 📖 R. v. Blaue, [1975] 1 WLR 1411The accused stabbed a young woman who was a Jehovah's Witness. She refused a blood transfusion on religious grounds and died. The Court of Appeal upheld the conviction for manslaughter. Lawton LJ said that those who use violence on other people must take their victims as they find them. This means that the victim's religious beliefs and consequential refusal of treatment do not break the chain. Rule: the thin skull rule extends to psychological and religious as well as physical vulnerabilities. | | --- |

| 📖 R. v. Hayward, (1908) 21 Cox CC 692The accused chased his wife into the street shouting threats. She collapsed and died. The medical evidence showed she suffered from a rare thyroid condition that made her susceptible to fatal shock in circumstances of fright. The Court held that the accused was liable for manslaughter. The thin skull rule applied. Rule: a victim's undisclosed physical fragility does not relieve the accused of liability for the result. | | --- |

| 📖 Rewaram v. State of Madhya Pradesh, AIR 1978 SC 1548The accused caused burn injuries to his wife. She died after developing hyperpyrexia, a rare complication involving abnormally high body temperature. The Supreme Court held that the death was caused by the injuries and by the complication they set off. The chain of causation was intact. Rule: a complication of the injury, even where uncommon, does not break the chain. Bringing forward or hastening death is causing death. | | --- |

Contributory acts of the victim and third parties

Where the victim's own act contributes to the result, causation is not broken so long as the accused's act remains a substantial and operating cause. Failure of the victim to obtain medical help, or refusal to accept treatment, generally does not break the chain.

| 📖 R. v. Dear, [1996] Crim LR 595The accused inflicted stab wounds on the victim. The victim, after being treated, either reopened his wounds or failed to look after them and bled to death. The Court of Appeal held that the accused's act was still the operating cause. The victim's neglect of himself did not break the chain. Rule: the victim's failure to mitigate the injury does not break the chain of causation. | | --- |

| 📖 Moti Singh v. State of Uttar Pradesh, AIR 1964 SC 900The accused caused gunshot injuries to the deceased. The deceased was discharged from hospital in an improved condition, but died three weeks later. No post mortem was conducted. The Supreme Court set aside the conviction under Section 302 IPC, holding that the prosecution had failed to prove that the death was caused by the injuries and not by some other cause. Rule: the prosecution must prove causation. Where the connection is not established, the accused cannot be convicted of causing death. | | --- |

5. Causation under the Bharatiya Nyaya Sanhita

Section 100 BNS and its Explanations

Section 100 of the BNS defines culpable homicide and, through its Explanations (carried forward from Section 299 IPC), codifies the doctrine of causation in the context of homicide. The Explanations answer three recurring questions: what happens when the victim was ill, what happens when medical treatment was imperfect, and what happens when the accused's act combined with the victim's own condition to cause the death.

Statutory illustrations of causation

| Explanation 1: pre existing condition of the victimA person who causes bodily injury to another who is labouring under a disorder, disease or bodily infirmity, and thereby accelerates the death of that other, shall be deemed to have caused his death.This is a codification of the thin skull rule. Where the victim's pre existing condition contributed to the death, the accused remains liable if he accelerated it. | | --- |

| Explanation 2: imperfect medical treatmentWhere death is caused by bodily injury, the person who causes such bodily injury shall be deemed to have caused the death, although by resorting to proper remedies and skilful treatment the death might have been prevented.This is the statutory version of the substantial cause rule from R. v. Smith. Ordinary or imperfect medical treatment does not break the chain of causation. Only palpably wrong treatment (Jordan's case) can. | | --- |

| Explanation 3: causing death of a child in the wombThe causing of the death of a child in the mother's womb is not homicide. But it may amount to culpable homicide to cause the death of a living child if any part of that child has been brought forth, though the child may not have breathed or been completely born.This Explanation sets the boundary of the human being for the purposes of homicide. | | --- |

Illustrations that examiners quote

Illustration (b) to Section 299 IPC, retained in substance under Section 100 BNS, is the classical Indian statement of causation through an innocent agent: A knows Z to be behind a bush. B does not know it. A, intending to cause or knowing it to be likely to cause Z's death, induces B to fire at the bush. B fires and kills Z. B may be guilty of no offence, but A has committed the offence of culpable homicide. Causation runs through B, who is treated as an innocent agent.

Illustration (c) confirms the same principle in a different setting: A, by shooting at a fowl with intent to kill and steal it, kills B, who is behind a bush. A had no knowledge that B was there. A is guilty of causing B's death, though he had no intention to kill B, provided the killing was likely to be a probable consequence of shooting at the fowl.

6. Consolidated Landmark Judgments

For quick revision. Learn the name, the citation, the ratio, and the factual anchor. In a question on causation, cite at least one English authority (for doctrine) and one Indian authority (for application).

• R. v. White, [1910] 2 KB 124. Cyanide in the drink did not kill. No factual causation. Attempted murder only. Anchor case for the but-for test.
• R. v. Smith, [1959] 2 QB 35. Stab wound and poor medical treatment. Original wound remained the substantial cause. Chain not broken by imperfect treatment.
• R. v. Jordan, (1956) 40 Cr App R 152. Stab wound and palpably wrong treatment. Treatment was the sole cause of death. Chain broken.
• R. v. Blaue, [1975] 1 WLR 1411. Jehovah's Witness refused transfusion. Thin skull rule extends to religious beliefs. Chain not broken.
• R. v. Hayward, (1908) 21 Cox CC 692. Chase and thyroid condition. Thin skull rule for physical fragility. Accused liable.
• R. v. Pagett, (1983) 76 Cr App R 279. Human shield case. Reasonable police response is not a novus actus. Accused liable for the death of the shield.
• R. v. Roberts, (1971) 56 Cr App R 95. Victim jumped from moving car. Foreseeable response of victim. Chain not broken.
• R. v. Dear, [1996] Crim LR 595. Victim's neglect of wounds. Chain not broken. Accused remains liable.
• Rewaram v. State of Madhya Pradesh, AIR 1978 SC 1548. Burn injuries followed by hyperpyrexia. Chain of causation intact. Acceleration of death is causing death.
• Joginder Singh v. State of Punjab, (1979) 4 SCC 401. Deceased jumped from wall of his own accord. Independent act. Chain broken.
• Moti Singh v. State of Uttar Pradesh, AIR 1964 SC 900. Cause of death unproved after discharge. Conviction for murder set aside. Prosecution must establish causation.