Lecture 3 - General Part 1: Actus Reus and Mens Rea
Building a Criminal Offence
1. Actus reus – the conduct element of the crime (the action of committing the crime)
2. Mens rea – the mental element of crime – guilty mind (intention/recklessness/gross
negligence)
3. Absence of a recognised defence – an excuse or justification precluding liability even
where the offence is made out (self-defence/duress)
Elements of a criminal offence = actus reus + mens rea + absence of a recognised defence
Negligence – falling below an appropriate standard of care
Recklessness – state of mind where a person deliberately and unjustifiably pursues a course of
action while consciously disregarding any risks flowing from this action
Gross negligence – a conscious or voluntary act or omission in reckless disregard of a legal
duty and the consequences to another party
Murder – to do an act or omission, recognised by common law, that causes the death or
grievous bodily harm (GBH) of another person (actus reus)
- Mens rea of murder is an intention to cause death or an intention to cause GBH
Omission – failure to act
Strict liability offences – offences that don’t carry a mens rea element
- Do not require mens rea, just the act of the crime, actus reus, is enough
Structure of Murder (most serious):
Actus reus – A does an unlawful act or omission which causes the death of B
Mens rea – A intends to cause death or GBH
Absence of a defence – A does not act in self-defence/under duress or loss of
control/diminished responsibility (partial defences)
- Partial defences – the action is caused by ‘loss of control’ or with ‘diminished
responsibility’ (only for the crime of murder)
o This reduces murder to manslaughter
- Loss of control – the defendant must at the time of the offence have lost self-control
resulting in them killing a person in one of three types of situations: where the defendant
fears serious violence, when certain things have been said or done which amount to
circumstances of an extremely grave character and caused the defendant to have a
justifiable sense of being seriously wronged, or when a combination of the first two
situations applies
- Diminished responsibility – a potential defense by excuse by which defendants argue
that although they broke the law, they should not be held fully criminally liable for doing
so as their mental functions were diminished or impaired
- Murder does not allow for a reckless defence – only through an intention, either to kill or
to cause GBH
, Structure of Battery (least serious):
Actus reus – A does an act or omission which causes the unlawful application of force to B
Mens rea – A intends or is reckless about causing the unlawful application of force
Absence of a defence – A does not act in self-defence or under duress
The Actus Reus
Voluntarism – need to establish that someone has acted in a voluntary way
- Automatism – (sane automatism) a common law principle that a that states no act is
punishable if it is done involuntarily
o An act done by the muscles without any control of the mind (such as a spasm,
reflex action, or a convulsion), or an act done by a person who is not conscious
of what he is doing (suffering from concussion or whilst sleep walking)
o Results in acquittal
- Insane automatism – (insanity) deal with internal rather than external forms of
automatism resulting from a disease of the mind (overwhelms one’s ability to act in a
voluntary way)
o Now held to include sleep walking and epilepsy
o Finding of insanity results in the acquittal but can lead to committal to hospital
- A person’s mind must have control over their conduct
o Responsibility, blame and culpability
o Liberal emphasis placed on the autonomy or free will of the suspect as the basis
for conviction and punishment
Omissions liability – there is no specific duty to rescue in English law which reflects the
normative concerns about the inappropriateness of criminalising omissions, instead the law
limits criminal ability for omissions to particular restrictive circumstances
- On the basis that an individuals’ autonomy and freedom is valued above all else
o Omissions are far more intrusive on individual autonomy than criminalising acts
o Eg. an individual that walks past a child drowning in a shallow pool and the child
dies – they are not guilty of murder
- Exceptions to this principle:
o Specific statutory or common law offences that are expressly defined as capable
of being committed by omission (usually in quasi-criminal offences)
▪ Failing to care for children, to provide a breath specimen, to file an annual
return, and refusing to assist a police officer when called upon to aid in
restoring the peace
o General principles in common law that impliedly allow some general offences to
be committed by omission
o If not expressly excluded, most criminal offences can be committed by omission
▪ Cannot commit unlawful act manslaughter by omission but can commit
gross negligence manslaughter by omission
- When will a common law duty to act be found:
o Recognised relationships – parents to a child, spouse to spouse
Building a Criminal Offence
1. Actus reus – the conduct element of the crime (the action of committing the crime)
2. Mens rea – the mental element of crime – guilty mind (intention/recklessness/gross
negligence)
3. Absence of a recognised defence – an excuse or justification precluding liability even
where the offence is made out (self-defence/duress)
Elements of a criminal offence = actus reus + mens rea + absence of a recognised defence
Negligence – falling below an appropriate standard of care
Recklessness – state of mind where a person deliberately and unjustifiably pursues a course of
action while consciously disregarding any risks flowing from this action
Gross negligence – a conscious or voluntary act or omission in reckless disregard of a legal
duty and the consequences to another party
Murder – to do an act or omission, recognised by common law, that causes the death or
grievous bodily harm (GBH) of another person (actus reus)
- Mens rea of murder is an intention to cause death or an intention to cause GBH
Omission – failure to act
Strict liability offences – offences that don’t carry a mens rea element
- Do not require mens rea, just the act of the crime, actus reus, is enough
Structure of Murder (most serious):
Actus reus – A does an unlawful act or omission which causes the death of B
Mens rea – A intends to cause death or GBH
Absence of a defence – A does not act in self-defence/under duress or loss of
control/diminished responsibility (partial defences)
- Partial defences – the action is caused by ‘loss of control’ or with ‘diminished
responsibility’ (only for the crime of murder)
o This reduces murder to manslaughter
- Loss of control – the defendant must at the time of the offence have lost self-control
resulting in them killing a person in one of three types of situations: where the defendant
fears serious violence, when certain things have been said or done which amount to
circumstances of an extremely grave character and caused the defendant to have a
justifiable sense of being seriously wronged, or when a combination of the first two
situations applies
- Diminished responsibility – a potential defense by excuse by which defendants argue
that although they broke the law, they should not be held fully criminally liable for doing
so as their mental functions were diminished or impaired
- Murder does not allow for a reckless defence – only through an intention, either to kill or
to cause GBH
, Structure of Battery (least serious):
Actus reus – A does an act or omission which causes the unlawful application of force to B
Mens rea – A intends or is reckless about causing the unlawful application of force
Absence of a defence – A does not act in self-defence or under duress
The Actus Reus
Voluntarism – need to establish that someone has acted in a voluntary way
- Automatism – (sane automatism) a common law principle that a that states no act is
punishable if it is done involuntarily
o An act done by the muscles without any control of the mind (such as a spasm,
reflex action, or a convulsion), or an act done by a person who is not conscious
of what he is doing (suffering from concussion or whilst sleep walking)
o Results in acquittal
- Insane automatism – (insanity) deal with internal rather than external forms of
automatism resulting from a disease of the mind (overwhelms one’s ability to act in a
voluntary way)
o Now held to include sleep walking and epilepsy
o Finding of insanity results in the acquittal but can lead to committal to hospital
- A person’s mind must have control over their conduct
o Responsibility, blame and culpability
o Liberal emphasis placed on the autonomy or free will of the suspect as the basis
for conviction and punishment
Omissions liability – there is no specific duty to rescue in English law which reflects the
normative concerns about the inappropriateness of criminalising omissions, instead the law
limits criminal ability for omissions to particular restrictive circumstances
- On the basis that an individuals’ autonomy and freedom is valued above all else
o Omissions are far more intrusive on individual autonomy than criminalising acts
o Eg. an individual that walks past a child drowning in a shallow pool and the child
dies – they are not guilty of murder
- Exceptions to this principle:
o Specific statutory or common law offences that are expressly defined as capable
of being committed by omission (usually in quasi-criminal offences)
▪ Failing to care for children, to provide a breath specimen, to file an annual
return, and refusing to assist a police officer when called upon to aid in
restoring the peace
o General principles in common law that impliedly allow some general offences to
be committed by omission
o If not expressly excluded, most criminal offences can be committed by omission
▪ Cannot commit unlawful act manslaughter by omission but can commit
gross negligence manslaughter by omission
- When will a common law duty to act be found:
o Recognised relationships – parents to a child, spouse to spouse
