The Courts have had very little trouble dealing with positive act cases: it is clear that a positive act to kill someone, such as picking up a knife and stabbing your victim, constitutes the actus reus of murder. However, the courts have found the status of omissions (a failure to act) which lead to a death far harder to grapple with.
Traditionally, it is stated that there is no duty to rescue in this country. This means that there is no general duty for one person to prevent the death of another. For example, if I see someone drowning and omit to save them, I will not face criminal liability for their death in England. The position is different in France, where a duty to rescue is imposed.
Whilst the courts have established that some omissions can form the basis of a murder conviction, the criminal law has also attempted to differentiate between positive conduct and omissions which result in death. It is much harder to ground a murder charge on the basis of an omission than a positive action.
In order for an omission to give rise to potential liability for murder, the defendant must firstly be under a duty, imposed by the law, to act to save the victim. The defendant must then breach that duty. Such a duty will only be imposed in limited circumstances and it is these circumstances which the cases below illustrate.
An omission, or a failure to act, is capable of amounting to the actus reus of murder where the defendant has a duty of care towards the victim.
R v Gibbons and Proctor 
The Court held that a parent owes a duty of care towards their child.
R v Instan 
In R v Instan, the court stated clearly that an omission is capable of amounting to a killing. This case also provides an example of a situation where a duty of care to the victim is substantiated.
R v Stone and Dobinson 
R v Stone and Dobinson is an example of circumstances where a duty to prevent the victim’s death was found by a court. The Court emphasised the defendant’s assumption of responsibility to the victim.
R v Pittwood 
R v Pittwood establishes that the necessary duty of care required for an omission to constitute the actus reus of murder can stem from a contractual duty.
R v Evans 
R v Evans (Gemma) is an example where the defendant was under a duty to act, and by failing to act was found guilty of an offence.
R v Miller 
The creation of a dangerous situation is capable of creating a duty to act to avert that situation from coming in to being. The failure of the defendant to act can then constitute the actus reus of the offence.
DPP v Santana-Bermudez 
The Court confirmed the correctness of R v Miller: where the defendant creates a dangerous situation and omits to avert the consequences of his actions, he can be liable if reasonably foreseeable harm occurs.