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This article is written by Akshita Jain who is pursuing a Certificate Course in Advanced Criminal Litigation & Trial Advocacy from LawSikho.


We have generally known that when a person causes injury to the other, he is liable to pay damages to the person who is injured. And when it comes to crime, one more element adds to the intention of the accused. So, for a crime to be proved there must be actus reus (conduct of the accused) as well as mens rea (guilty intention of accused).

However, what if the consequences of your act turn out to be completely different from what you actually intended? Would you be liable for the act that you intended to commit or the result that has actually come out? Let us consider a situation slightly different from the aforesaid one. In this situation a person intended to commit some wrong or crime, but while he was giving effect to it some other person’s act intervened in between, and that intervening act became the reason for the resulting offence.

For instance, imagine X wanted to kidnap Y so he mixed sleeping pills in Y’s water, which were innocuous. Y drank the water, but before the sleeping pills would start working, he took a bite from his food in which someone else had already mixed poison, due to which Y immediately died. The reason for Y’s death was poison. Now what would X be liable for, murder? or Attempt to kidnap? or not liable for anything at all? An additional element in determining the liability in such cases is the “causation”, which gives rise to the question whether or not the act of the accused is the exact or direct cause of the result. This article aims to elucidate the concept of causation, its various aspects as well as to wipe off the confusion with regards to all the aforementioned questions.

Doctrine of causation

The term ‘causation’ generally implies the relation between the cause and effect of any particular occurrence. Likewise, in legal terms, causation means the connection between the conduct of the defendant and the injury suffered by the plaintiff. The basic idea behind the doctrine of causation is that a person must face liability for the outcome of his own actions. It is the concept of causation that helps to determine the extent of liability emerging out of a legal wrong on the part of a defendant. It basically acts like a sieve that filters out all the external factors unlinked with the defendant’s conduct which contributed to the consequences, and hence holds him responsible only for his role. For example, A damaged the brakes of B’s car so that B meets an accident and dies. While driving, B dies due to a cardiac arrest and not because of the brake failure. Here, despite the presence of mens rea on the part of A, he could not be held liable for murder as the death of B did not occur because of failed brakes, which was the act of A. He could, however, be held liable for attempt to murder. 

The doctrine of causation could be established by its two elements which are ‘factual causation’ and ‘legal causation’. In other words, these are the two elements of causation that ascertain whether or not the defendant could be held liable for the injury caused to the aggrieved. If yes, then to what extent he could be made responsible for the same?

Factual causation

In order to establish the factual causation, a test known as “but for” test is used, which says that “but for the defendant’s conduct, the injury would not have resulted”. In simple words, it means that if the defendant had not performed an act, then the plaintiff would not have suffered the harm by any means at all. To prove factual causation, it must be proved that the defendant’s action was a necessary condition for the consequences faced by the plaintiff. On passing the ‘but for’ test, the defendant could be held liable for the damage. 

In the case of R v. White, the defendant attempted to kill his mother (deceased) by adding poison in her drink. But the deceased died of a heart attack soon, even before the poison took effect. Here the “but for” test was applied and was observed that but for the defendant’s attempt to kill the deceased by poisoning her, she would still have died owing to the heart attack. Therefore, the defendant was liable for attempt to murder, but not murder.

In another case of Barnett v. Chelsea and Kensington Hospital Management Committee, the deceased felt very sick so he went to the hospital. He was asked to go home instead of getting treated. Later, he died of arsenic poisoning. The Court held that but for the hospital’s conduct, the deceased would still have died as, firstly, the doctor was at home and probably have not been able to check the deceased in time, secondly, even if the doctor had checked no antidote was readily available so as to give it to the deceased in time.

In R v. Pagett, the defendant fired at the police and when he was fired back by the police, he pulled a pregnant teenager girl in front of him in order to protect himself behind her due to which she died. In this, the Court observed that but for the conduct of the defendant, the deceased would not have died. Hence, the defendant, being the factual cause, was held liable for manslaughter. 

However, there is a limitation with regards to the application of ‘but for’ test. If we apply the said test in cases where there have been more than one causes of the resulting damage, and all of them individually are sufficient to cause such damage, then all the wrongdoers may escape the liability by pleading for this defence. For example, A stabbed C in the abdomen and at the same time B stabbed C in the chest and C died. Both these wounds were fatal enough to kill C. Here, if we apply the ‘but for’ test, both A and B would escape the liability because even if none of them had not stabbed C, he would still have died.

Legal causation

After establishing factual causation, it is legal causation that needs to be established. In case of legal causation, the question that is asked is “whether or not the act of the defendant was the ‘operative’ and ‘substantial’ cause of the consequences”.

For instance, A hit B with a bat due to which B had a hand fracture. While B was being taken to the hospital in an ambulance, the ambulance met with an accident and B died in that ambulance crash. Now, in order to determine the legal causation, we need to see if the act of A was the operative and substantial cause of death of B or not. Clearly, the operative and substantial cause of B’s death is the accident and not A’s act, so he is not liable for killing B, although he could be made liable for the initial grievous hurt that he inflicted upon B.

So, what we are basically doing to prove innocence of the accused persons or commuting their liability in such cases is that, firstly, we are proving that there has been a break in the chain of causation of the defendant’s act and the plaintiff’s injury. Secondly, we are identifying the act that has broken the said chain. And finally, we are proving that the aforesaid act which has broken the chain is the actual cause of the harm that has been suffered by the aggrieved person. This leads us to another crucial concept known as “novus actus interveniens”.

Novus actus interveniens

Novus actus interveniens is a Latin maxim which literally means “new intervening act”. Basically, it refers to a new act that takes place independently after the defendant has concluded his act and contributes to the resulting harm. What Novus actus does is that it breaks the continuous series of action between the offender’s conduct and the resulting injury. Hence, it helps the wrongdoer to escape or limit the liability arising from the final outcome. 

An essential condition for an act to be novus actus is that such an act must not have been reasonably foreseeable by the defendant. If the intervening act is found to be reasonably foreseeable at the time of the defendant’s act, then it would not be considered a novus actus. A novus actus may either be an act of the injured person himself, or an act of third party, or an act of God, but it could never be an act of the wrongdoer himself. Thus, if a person dies due to lightning over him after he was injured by the defendant, a Novus actus gets created by the act of god in such a case.

The concept of novus actus interveniens must not be confused with “contributory negligence”. In case of contributory negligence, the negligent act or omission is done by the aggrieved person before the occurrence of the event that leads to injury. For instance, in an accident between a car and a motorbike, if the motor bike rider was riding with a speed more than the limit, then it would be contributory negligence on the part of the rider. However, in case of novus actus interveniens, the intervening act takes place after the defendant has already committed the act which would lead to damage in the first place. 

In the case of Haynes v. Harwood, the defendant owed a two-horse van which was left unattended by his servant on a busy street. A kid threw stones on the horses due to which they bolted on the street carrying the van with them. A police constable while trying to stop them suffered several injuries for which he claimed compensation. Now, the important question that arose, in this case, was whether this act of intervention by the rescuer is novus actus interveniens, which breaks the chain of causation so that the initial negligence of the defendant be considered to be remote cause of the rescuer’s injury? Here, it was held that the rescuer’s act was not a kind of act that could make the defendant’s negligence a remote cause for the plaintiff’s injury. The defendant pleaded that his negligence is a remote cause while the child’s mischief was the proximate cause for the damage, however, the Court observed that such a mischief on the part of a child was reasonably foreseeable due to which it could not be considered a novus actus interveniens and defendant was held liable.

In another case of Lynch v. Nurdin, the defendant left his horse cart on the road. Certain children started playing with it and one child jumped on the cart setting the horse in motion, due to which he suffered injuries. The Court held that although the misconduct of the child was novus actus interveniens, the proximate cause of the accident was defendant’s negligence because such mischievous behaviour on the part of children could very well be apprehended especially when you have left an open opportunity for them to do so.


It is often said that justice must not only be done but also must appear to be done. And what we ordinarily understand from justice being done is that the offender or the wrongdoer is held responsible for his or her acts and is punished or made to compensate the injured person. Settlement of liability of the wrongdoer is one of the most crucial stages of any legal proceeding because it is one of those elements that reveals public whether justice has been done or not.

Therefore, it is very essential to set such liability in a very accurate manner. Punishing a wrongdoer is important, but the more important thing is that he is punished for only his acts and none other. If a person has committed sexual harassment, but he is being punished for rape, this is injustice. This person might be a monster in the eyes of society for committing sexual harassment, but still he has not committed rape and thus getting punished for the latter could not be called justice.

The fact that the Acts and Codes of our country provides specific punishments for different wrongs clearly indicates their aim to punish a person to the extent of his wrong acts and not further. And as it has been discussed above, the proper analysis of the chain of causation could be of very much help in determining the exact liability of the wrongdoer. Therefore, the chain of causation needs to be broken for proving innocence.


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