OVERVIEW
Self-defence is a complete common-law defence. It recognises that a person may use reasonable force to defend themselves or another person from an attack or threatened attack. The defence does not create a licence to retaliate or punish: the force must be used for a genuinely defensive purpose and must be reasonable in the circumstances as the accused honestly believed them to be.
The issue often arises in prosecutions for assault, wounding and homicide. The precise charge does not determine whether the defence is available; the court examines the perceived threat, the need to act and the nature of the accused's response.
THE LEGAL FRAMEWORK
Necessity and reasonable force
Hong Kong courts examine both the accused's honest perception of the circumstances and the objective reasonableness of the force used in response.
Was force honestly believed to be necessary?
The court first considers the circumstances as the accused honestly believed them to be. The belief may be mistaken, although the reasonableness or unreasonableness of the belief is relevant when deciding whether it was genuinely held. Defensive force may be used to protect oneself or another person, and a person does not necessarily have to wait to be struck before acting.
Was the force used reasonable?
The court then decides whether the force used was reasonable in those believed circumstances. This is an objective assessment informed by the accused's perception of the danger. An honest and instinctive reaction to an imminent attack is important evidence, but force which is disproportionate or continues after the danger has passed may fall outside the defence.
The prosecution bears the legal burden
The accused must point to evidence capable of raising self-defence. Once the issue is properly raised, the prosecution must satisfy the court beyond reasonable doubt that the accused was not acting in lawful self-defence.
OFFENCES TO WHICH SELF-DEFENCE MAY APPLY
From common assault to homicide
Self-defence may apply to the following offences, subject always to the evidence and the legal elements of the particular charge.
| Offence | Application of self-defence |
|---|---|
| Common assault | Self-defence may answer an allegation of threatened or applied unlawful force if the accused honestly believed defensive force was necessary and the response was reasonable. |
| Assault occasioning actual bodily harm | The defence may apply even where bodily harm was caused. The resulting injury is relevant to, but does not by itself determine, whether the force was reasonable. |
| Wounding or inflicting grievous bodily harm — section 19 | Self-defence may apply to a section 19 allegation, but the seriousness of the wound and the manner in which it was inflicted will be important when assessing the reasonableness of the force. |
| Wounding or causing grievous bodily harm with intent — section 17 | The defence is legally available, including where serious defensive force was used, but the prosecution may rely on the weapon, injuries, continuation of force and surrounding circumstances to dispute necessity or reasonableness. |
| Assaulting a police officer — section 36 | The lawfulness of the officer's conduct and the accused's honest understanding of the circumstances may be central. Reasonable force may be used in defence against unlawful violence, but disagreement with or resistance to lawful police action is not self-defence. |
| Murder and manslaughter | A successful plea of self-defence is a complete defence to homicide. There is no general partial defence of excessive self-defence: if the force was not reasonable, the complete defence fails, although other issues or defences may arise on the facts. |
EVIDENTIAL CONSIDERATIONS
The incident must be assessed as it appeared at the time
The perceived threat
What the other person said or did, whether a weapon was seen, the immediacy of the danger, earlier threats known to the accused and the number, size and position of the people involved may all be relevant.
The nature and duration of the response
The court considers the force used, the sequence and number of blows, any weapon, whether the accused pursued the other person, and whether force continued after the threat had ended.
Contemporaneous and objective evidence
CCTV, injuries, medical evidence, emergency calls, messages, photographs, witness accounts and the accused's first explanation may assist in reconstructing a fast-moving incident.
IMPORTANT LIMITS
Defence is different from retaliation
The court distinguishes force used to avert a danger from revenge after the danger has passed. A person's opportunity to withdraw may be relevant to whether force was honestly thought necessary and whether the response was reasonable, but the issue is not determined by a rigid rule that the accused had to retreat.
Whether a weapon or serious force was reasonable depends on the danger as the accused honestly perceived it. The assessment is highly fact-sensitive and must avoid judging a sudden confrontation as though the accused had time for calm and precise calculation.
HOW MCS CAN ASSIST
Presenting the full circumstances of a defensive act
MCS can advise from the investigation stage, prepare clients for police interview and identify the evidence needed to establish how the incident appeared to them at the time. We can obtain and analyse CCTV, medical material, communications and witness evidence, and test whether the prosecution can disprove self-defence beyond reasonable doubt.
We represent clients in assault, wounding and homicide proceedings and can advise on self-defence, defence of another person and any other defence or alternative outcome supported by the evidence.