When may you act in self-defence or private defence?
Self-defence and private defence are the same thing, except that "self-defence" is a very narrow application of private defence. Self-defence can only apply to you acting for your interests, whereas private defence applies to you and anyone around you. An act of private defence is directed expressly at the wrongdoer and nobody else. A private citizen invoking private defence acts on behalf of the state, and that citizen's conduct must be clearly limited. Using lethal force (such as a firearm) can only be applied in very specific circumstances.
Always bear in mind the following when considering private defence:
- Everyone has a right to life, and you should avoid killing someone as much as possible.
- Everyone is innocent until a court decides they are guilty of a crime.
- Everyone has the right to dignity and property.
The three requirements for using private defence are as follows:
1There must be an attack that has commenced or is imminent.
You may not "pre-emptively defend" and there should be a clear indication that the attack has begun or is about to begin.
2There must be a protected interest and may include life or limb or property.
The degree of force you may use to defend a protected interest is different depending on the circumstances.
Example: Lethal force is not justified when defending property interests.
3The attack against the protected interest is unlawful/illegal.
Example: Your car is a protected interest as your property. If the state lawfully confiscates your car because it was not roadworthy and unlicensed, you cannot defend your car from being confiscated.
How to use force in private defence:
The force you use must be necessary to avert the attack.1
Always try to avoid using force. If you can escape, you should do this instead!
The force used must be reasonable under the circumstances.2
You may not use more force than the attacker. If the attacker slaps you, you cannot shoot or stab the attacker! Strict proportionality is not required (such as knife vs knife), but it must be reasonable. If the circumstances permit, you should warn the attacker to cease.
The force must be directed against the attacker. 3
If a stranger breaks into your house while his friend waits in the car to help with an escape, you cannot apply force to both the stranger and the "getaway driver".
Where does "lethal force" fit in?
This may all sound very complex for such a seemingly straight forward situation, but it is necessary for the context. If the three requirements (an attack, against a protected interest, that is unlawful) are met, then you must consider how much force you will use to defend the interest in question, ranging from verbal shouts to lethal force.
Lethal force is relevant to the proportionality of an attack, namely, it should only used when a life is in danger, or if there is great risk of significant bodily violation such as grievous bodily harm or rape, and you had no other way of avoiding the harm. A court will objectively consider what a reasonable person would have done if inserted into such a situation.
Source: Principles of Criminal Law, fifth edition, Jonathan Burchell, pages 121-131.