Homicide offences - Involuntary manslaughter (unlawful act and gross negligence)

Learning Outcomes

After reading this article, you will be able to explain and apply the elements of involuntary manslaughter, including both unlawful act and gross negligence manslaughter. You will be able to distinguish between these offences, identify their actus reus and mens rea requirements, and analyse how the courts determine dangerousness, duty of care, breach, and causation. You will also be able to apply these principles to SQE1-style scenarios and avoid common pitfalls.

SQE1 Syllabus

For SQE1, you are required to understand involuntary manslaughter as a key homicide offence. Focus your revision on:

• the elements of unlawful act manslaughter (constructive manslaughter)
• the elements of gross negligence manslaughter
• the distinction between unlawful act and gross negligence manslaughter
• the requirements for dangerousness, duty of care, breach, causation, and grossness
• how the courts assess risk of death and the role of omissions
• applying these rules to practical scenarios and avoiding common errors

Test Your Knowledge

Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision.

1. Which of the following is required for unlawful act manslaughter?
   1. a civil wrong
   2. a dangerous and unlawful act
   3. an omission
   4. proof of intention to kill
2. Which of the following is NOT an element of gross negligence manslaughter?
   1. a duty of care owed to the victim
   2. a breach of that duty
   3. intention to cause serious harm
   4. a risk of death that was obvious

3. True or false? For unlawful act manslaughter, the defendant must foresee the risk of death.

4. In gross negligence manslaughter, who decides whether the breach was "gross"?

Introduction

Involuntary manslaughter covers unlawful killings where the defendant did not intend to kill or cause grievous bodily harm. For SQE1, you must know the two main types: unlawful act manslaughter (also called constructive manslaughter) and gross negligence manslaughter. Each has distinct requirements and is assessed differently by the courts. This article explains the elements, key terms, and practical application of both offences.

Unlawful Act Manslaughter

Unlawful act manslaughter occurs when a person intentionally does an unlawful and dangerous act that causes death, even if they did not intend harm. The prosecution must prove four elements:

1. The defendant did a positive act (not an omission).
2. The act was a criminal offence (not merely a civil wrong).
3. The act was objectively dangerous.
4. The act caused the victim’s death.

Key Term: unlawful act manslaughter
A form of involuntary manslaughter where death results from a defendant’s intentional, unlawful, and dangerous act.

Key Term: dangerous act
An act that all sober and reasonable people would recognise as subjecting another to the risk of some physical harm.

The Unlawful Act

The act must be a crime requiring a positive action. Omissions do not suffice. The principal offence can be any crime (e.g., assault, criminal damage, burglary), but not negligence or a civil wrong.

Dangerousness

The act must be dangerous as judged by the objective standard: would all sober and reasonable people recognise the risk of some harm? The defendant’s own awareness is irrelevant.

Causation

The unlawful act must cause the death, applying normal rules of factual and legal causation.

Worked Example 1.1

A group of friends throw stones at passing trains as a prank. One stone breaks a window, fatally injuring a passenger. Can the thrower be convicted of unlawful act manslaughter?

Answer: Yes. Throwing stones at a train is a criminal offence and a dangerous act. The act caused death. The defendant need not foresee death or serious harm.
Exam Warning
For unlawful act manslaughter, the act must be a crime and a positive act. Omissions, even if grossly negligent, cannot be the basis for this offence.

Worked Example 1.2

A defendant pushes someone during an argument. The victim falls, hits their head, and dies. The push was intended as a minor assault. Is this unlawful act manslaughter?

Answer: Yes. The push is a battery (a criminal offence), and pushing someone is objectively dangerous. The act caused death.

Gross Negligence Manslaughter

Gross negligence manslaughter arises when a person owes a duty of care to the victim, breaches that duty in a grossly negligent way, and causes death. The prosecution must prove:

1. The defendant owed the victim a duty of care.
2. The defendant breached that duty.
3. The breach caused the death.
4. The breach involved a serious and obvious risk of death.
5. The breach was grossly negligent.

Key Term: gross negligence manslaughter
A form of involuntary manslaughter where death results from a defendant’s gross breach of a duty of care.

Key Term: duty of care
A legal obligation to take reasonable care to avoid acts or omissions which could foreseeably injure another.

Key Term: gross negligence
Conduct so far below the standard expected of a reasonable person that it amounts to a crime deserving punishment.

Duty of Care

The duty of care is assessed using civil law principles. It can arise from relationships (doctor-patient, employer-employee, parent-child), contracts, or creating a dangerous situation.

Breach and Risk

The defendant must breach the duty, and the breach must create a serious and obvious risk of death, not just injury.

Causation (Gross Negligence Manslaughter)

The breach must cause the death, applying normal causation rules.

Grossness

The breach must be so bad as to amount to a crime. The jury decides if the negligence is "gross."

Worked Example 1.3

A landlord ignores repeated complaints about a faulty gas boiler. The boiler leaks carbon monoxide, killing a tenant. Is this gross negligence manslaughter?

Answer: Yes. The landlord owed a duty of care, breached it, the breach caused death, the risk of death was obvious, and the conduct was grossly negligent.

Revision Tip

For gross negligence manslaughter, always check for a duty of care, a breach, causation, an obvious risk of death, and whether the breach is gross.

Comparing the Offences

Key Point Checklist

This article has covered the following key knowledge points:

• Unlawful act manslaughter requires a positive, criminal, and dangerous act causing death.
• The act must be objectively dangerous; the defendant’s awareness is irrelevant.
• Gross negligence manslaughter requires a duty of care, breach, causation, serious risk of death, and grossness.
• The jury decides whether negligence is "gross" in gross negligence manslaughter.
• Omissions can only form the basis of gross negligence manslaughter, not unlawful act manslaughter.
• For SQE1, be able to distinguish between the two offences and apply the correct elements to scenarios.

Key Terms and Concepts

• unlawful act manslaughter
• dangerous act
• gross negligence manslaughter
• duty of care
• gross negligence