Unlawful Killing
UK Criminal Law – Exam-Ready Notes
Comprehensive and structured notes covering the law of homicide in England and Wales,
including murder, voluntary manslaughter, involuntary manslaughter, and the statutory
partial defences.
This document includes:
• Clear breakdown of actus reus and mens rea
• Authoritative case law and statutory tests
• Step-by-step offence structures
• Flow-based exam frameworks and comparison tables
• Focused application for problem-question answers
Suitable for UK undergraduate law, criminology, and PGDL students.
CONTENTS
1. Actus Reus of Unlawful Killing (p. 1)
– Voluntary act and omissions
– Causation (factual and legal)
– Death and “human being” requirement
2. Mens Rea of Unlawful Killing (p. 2)
– Intention (direct and oblique)
– Key intention authorities
– Coincidence and transferred malice
3. Homicide and Manslaughter (p. 3)
– Structure of homicide offences
– Murder vs manslaughter overview
– Voluntary vs involuntary manslaughter
4. Involuntary Manslaughter (p. 4)
– Unlawful act manslaughter (elements and limits)
– Gross negligence manslaughter (elements and standard)
5. Partial Defences to Murder (p. 5)
– Loss of control
– Diminished responsibility
– Suicide pact
, Actus Reus
Sunday, 19 October 2025 20:25
The phrase actus non facit reum nisi mens sit rea means “an
act does not make a person guilty unless the mind is also
guilty.”
Thus, actus reus represents the external component —
what the defendant did (or failed to do) — while mens rea
represents what they thought or intended.
-> all the elements of a criminal offence except the accused
mental state
= the guilty act
The actus reus of an offence
can, and often does,
involve more than one
recognised form (listed below)
simultaneously.
Category Meaning Example / Key Case Why It’s a Type of Actus Reus
1. an act that is a willed Hill v Baxter (1958) – can Establishes that there must be Voluntary Conduct
Voluntary physical movement. It must use this case if the act a voluntary act before any
Conduct be something the was involuntary or liability can arise. For Actus Reus to be fulfilled, the defendants act must be voluntary.
defendant chose to do, voluntary.
rather than something that Involuntary: If the defendant’s movement or omission was not voluntary/of
happened to them their own free will, the law treats it as no act at all for criminal purposes.
2. Conduct Crimes where the conduct Perjury (Perjury Act The actus reus is complete upon
Crimes itself is prohibited — 1911) - lying under oath performing the conduct, Voluntary: an act that is a willed physical movement. It must be something
regardless of outcome is enough to fulfil perjury regardless of consequences. the defendant chose to do, rather than something that happened to them.
-> key case: Hill v Baxter [1958]
3. Failing to act where a legal • Special relationship – R The “guilty act” here is
Omissions duty exists can amount to v Gibbins & Proctor the failure to fulfil a recognised
actus reus. (1918) legal duty.
• Voluntary assumption
of care – R v Stone &
Dobinson (1977
• Contractual duty – R v
Pittwood (1902)
• Creation of a
dangerous situation – R
v Miller (1983)
• Statutory duty –
e.g. Road Traffic Act
1988, s.170
4. State of Liability for simply being in R v Larsonneur (1933) - The actus reus is the existence of
Affairs a prohibited situation — no illegally being in a a certain condition or
Crimes act required. country circumstance.
5. Result Crimes requiring Murder – unlawful killing The actus reus includes both the
Crimes the defendants action to (R v White [1910]). conduct and the resulting harm.
cause a specific result (e.g.
death, injury, damage).
6. (For result crimes) The • Factual causation – Connects the defendant’s act or
Causation defendant’s conduct “But for” test (R v omission to the consequence —
must cause the prohibited White [1910]) an essential part of proving actus
outcome. • Legal causation – reus in result crimes.
substantial and
operating cause (R v
Smith [1959]; R v
Cheshire [1991])
• Thin skull rule (R v
Blaue [1975])
UK Criminal Law – Exam-Ready Notes
Comprehensive and structured notes covering the law of homicide in England and Wales,
including murder, voluntary manslaughter, involuntary manslaughter, and the statutory
partial defences.
This document includes:
• Clear breakdown of actus reus and mens rea
• Authoritative case law and statutory tests
• Step-by-step offence structures
• Flow-based exam frameworks and comparison tables
• Focused application for problem-question answers
Suitable for UK undergraduate law, criminology, and PGDL students.
CONTENTS
1. Actus Reus of Unlawful Killing (p. 1)
– Voluntary act and omissions
– Causation (factual and legal)
– Death and “human being” requirement
2. Mens Rea of Unlawful Killing (p. 2)
– Intention (direct and oblique)
– Key intention authorities
– Coincidence and transferred malice
3. Homicide and Manslaughter (p. 3)
– Structure of homicide offences
– Murder vs manslaughter overview
– Voluntary vs involuntary manslaughter
4. Involuntary Manslaughter (p. 4)
– Unlawful act manslaughter (elements and limits)
– Gross negligence manslaughter (elements and standard)
5. Partial Defences to Murder (p. 5)
– Loss of control
– Diminished responsibility
– Suicide pact
, Actus Reus
Sunday, 19 October 2025 20:25
The phrase actus non facit reum nisi mens sit rea means “an
act does not make a person guilty unless the mind is also
guilty.”
Thus, actus reus represents the external component —
what the defendant did (or failed to do) — while mens rea
represents what they thought or intended.
-> all the elements of a criminal offence except the accused
mental state
= the guilty act
The actus reus of an offence
can, and often does,
involve more than one
recognised form (listed below)
simultaneously.
Category Meaning Example / Key Case Why It’s a Type of Actus Reus
1. an act that is a willed Hill v Baxter (1958) – can Establishes that there must be Voluntary Conduct
Voluntary physical movement. It must use this case if the act a voluntary act before any
Conduct be something the was involuntary or liability can arise. For Actus Reus to be fulfilled, the defendants act must be voluntary.
defendant chose to do, voluntary.
rather than something that Involuntary: If the defendant’s movement or omission was not voluntary/of
happened to them their own free will, the law treats it as no act at all for criminal purposes.
2. Conduct Crimes where the conduct Perjury (Perjury Act The actus reus is complete upon
Crimes itself is prohibited — 1911) - lying under oath performing the conduct, Voluntary: an act that is a willed physical movement. It must be something
regardless of outcome is enough to fulfil perjury regardless of consequences. the defendant chose to do, rather than something that happened to them.
-> key case: Hill v Baxter [1958]
3. Failing to act where a legal • Special relationship – R The “guilty act” here is
Omissions duty exists can amount to v Gibbins & Proctor the failure to fulfil a recognised
actus reus. (1918) legal duty.
• Voluntary assumption
of care – R v Stone &
Dobinson (1977
• Contractual duty – R v
Pittwood (1902)
• Creation of a
dangerous situation – R
v Miller (1983)
• Statutory duty –
e.g. Road Traffic Act
1988, s.170
4. State of Liability for simply being in R v Larsonneur (1933) - The actus reus is the existence of
Affairs a prohibited situation — no illegally being in a a certain condition or
Crimes act required. country circumstance.
5. Result Crimes requiring Murder – unlawful killing The actus reus includes both the
Crimes the defendants action to (R v White [1910]). conduct and the resulting harm.
cause a specific result (e.g.
death, injury, damage).
6. (For result crimes) The • Factual causation – Connects the defendant’s act or
Causation defendant’s conduct “But for” test (R v omission to the consequence —
must cause the prohibited White [1910]) an essential part of proving actus
outcome. • Legal causation – reus in result crimes.
substantial and
operating cause (R v
Smith [1959]; R v
Cheshire [1991])
• Thin skull rule (R v
Blaue [1975])
