General defences - Self-defence and defence of another

Learning Outcomes

After studying this article, you will be able to explain and apply the legal rules governing self-defence and defence of another in criminal law. You will understand when these defences are available, the requirements of necessity and reasonable force, how mistaken belief is treated, and the statutory framework. You will also be able to identify common pitfalls and apply these principles to SQE1-style scenarios.

SQE1 Syllabus

For SQE1, you are required to understand the following aspects of self-defence and defence of another. Focus your revision on:

• the legal requirements for self-defence and defence of another as general defences to criminal offences
• the necessity of force and the requirement that force used is reasonable in the circumstances
• the treatment of mistaken belief (including honest but mistaken belief and the effect of intoxication)
• the statutory framework, including s 3 Criminal Law Act 1967 and s 76 Criminal Justice and Immigration Act 2008
• the special rules for householders and the use of disproportionate force
• the limits of the defence (e.g. excessive force, pre-emptive strikes, duty to retreat)
• how these defences operate in practice and their application to SQE1-style questions

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. What two requirements must be satisfied for self-defence or defence of another to succeed as a general defence in criminal law?
2. Can a defendant rely on self-defence if they honestly but unreasonably believed force was necessary?
3. What is the effect of voluntary intoxication on a mistaken belief in the need for self-defence?
4. In what circumstances may a householder use disproportionate force against an intruder?

Introduction

Self-defence and defence of another are general defences available to all criminal offences in England and Wales. These defences justify conduct that would otherwise be criminal if the defendant used force to protect themselves, another person, or, in some cases, property. The law balances the right to personal safety with the need to prevent excessive or retaliatory violence.

The Legal Basis for Self-Defence

Self-defence and defence of another are recognised at common law and are supplemented by statute.

Key Term: self-defence
A general defence allowing a person to use reasonable force to protect themselves, another person, or, in some cases, property, where such force is necessary in the circumstances as the defendant believed them to be.

Key Term: reasonable force
The level of force that is proportionate to the threat faced, judged objectively but in light of the circumstances as the defendant honestly believed them to be.

Key Term: necessity
The requirement that force is used only when the defendant honestly believes it is needed to prevent harm to themselves or another.

Statutory Framework

The main statutory provisions are:

• Section 3 Criminal Law Act 1967: Allows reasonable force in the prevention of crime or in effecting a lawful arrest.
• Section 76 Criminal Justice and Immigration Act 2008: Clarifies the common law, including how reasonableness and mistaken belief are assessed, and provides special rules for householders.

Requirements for Self-Defence

To succeed, the defence must show:

1. Necessity: The defendant honestly believed it was necessary to use force.
2. Reasonable Force: The force used was reasonable in the circumstances as the defendant believed them to be.

Necessity of Force

The defendant must honestly believe that force is required to avert an imminent threat. The belief does not need to be correct, but it must be genuinely held.

Key Term: mistaken belief
An honest but incorrect belief by the defendant that force was necessary. The defence is available if the belief is genuinely held, even if unreasonable, unless the mistake is caused by voluntary intoxication.

Reasonable Force

The force used must be proportionate to the threat. The law recognises that people under attack cannot precisely measure their response, but force that is excessive will defeat the defence.

Worked Example 1.1

Scenario:
Sam is attacked in the street. He punches his attacker once, knocking him to the ground. The attacker is incapacitated, but Sam continues to kick him repeatedly.

Answer:
Sam's initial punch may be justified as reasonable force in self-defence. However, once the attacker is incapacitated, further kicks are excessive. The defence will fail for the later force.

Mistaken Belief and Self-Defence

A defendant may rely on self-defence even if they were mistaken about the need for force, provided the mistake was honestly held.

• If the mistake was due to voluntary intoxication, the defence is not available.

Worked Example 1.2

Scenario:
Alex, after drinking heavily, mistakenly believes someone is about to attack him and punches the person.

Answer:
Because Alex's mistaken belief was induced by voluntary intoxication, he cannot rely on self-defence.

Pre-Emptive Strikes and Duty to Retreat

A person does not have to wait to be attacked before using force if they honestly believe an attack is imminent. There is no legal duty to retreat, but evidence that the defendant tried to avoid violence may support the defence.

Special Rules for Householders

Section 76 CJIA 2008 provides that householders may use disproportionate force against intruders in their home, provided the force is not grossly disproportionate.

Key Term: householder case
A situation where a person uses force in self-defence while in or partly in a dwelling, against a person they believe to be a trespasser.

Worked Example 1.3

Scenario:
Jordan is woken by an intruder at night. He uses a cricket bat to strike the intruder, causing serious injury. The intruder is trying to escape at the time.

Answer:
If the force used was not grossly disproportionate, Jordan may be able to rely on the householder defence. However, if the intruder was fleeing and no longer a threat, the force may be excessive.

Limits of the Defence

• Excessive Force: If the force used is more than reasonable (or grossly disproportionate in a householder case), the defence fails.
• Retaliation or Revenge: The defence is not available for acts of retaliation or revenge.
• Mistake Due to Intoxication: A mistaken belief caused by voluntary intoxication cannot found the defence.

Exam Warning

The defence of self-defence is not available if the defendant's mistaken belief in the need for force was caused by voluntary intoxication. Always check the source of the mistake in SQE1 questions.

Application to Defence of Another

The same principles apply when force is used to protect another person. The defendant must honestly believe that intervention is necessary and use no more force than is reasonable in the circumstances.

Self-Defence and Defence of Property

Reasonable force may be used to protect property, but lethal force is rarely justified unless there is also a threat to personal safety.

Summary Table: Self-Defence and Defence of Another

Key Point Checklist

This article has covered the following key knowledge points:

• Self-defence and defence of another are general defences to all criminal offences.
• The defence requires both necessity (honest belief that force is needed) and reasonable force (proportionate response).
• A mistaken belief can found the defence if honestly held, unless caused by voluntary intoxication.
• There is no duty to retreat, but evidence of retreat may support the defence.
• Householders may use disproportionate force against intruders, provided it is not grossly disproportionate.
• Excessive force or acts of retaliation will defeat the defence.
• The same rules apply to defence of another as to self-defence.

Key Terms and Concepts

• self-defence
• reasonable force
• necessity
• mistaken belief
• householder case