When should you throw the first punch?

I advise against moving back in a face off. It allows the aggressor to step into your space and also has the added effect of making you look weak, making him/her grow in confidence.

 

It does also depend on the law in your country/state.

 

In the UK the rules are as follows:

Pre-emptive strikes
There is no rule in law to say that a person must wastruck first before it to be struck first before they may defend themselves, (see R v Deana, 2 Cr App R 75).

Retreating
Failure to retreat when attacked and when it is possible and safe to do so, is not conclusive evidence that a person was not acting in self defence. It is simply a factor to be taken into account rather than as giving rise to a duty to retreat when deciding whether the degree of force was reasonable in the circumstances (section 76(6) Criminal Justice and Immigration Act 2008). It is not necessary that the defendant demonstrates by walking away that he does not want to engage in physical violence: (R v Bird 81 Cr App R 110).

Use of Force against Those Committing Crime
Use of Force Prosecutors should exercise particular care when assessing the reasonableness of the force used in those cases in which the alleged victim was, or believed by the accused to have been, at the material time, engaged in committing a crime. A witness to violent crime with a continuing threat of violence may well be justified in using extreme force to remove a threat of further violence.

In assessing whether it was necessary to use force, prosecutors should bear in mind the period of time in which the person had to decide whether to act against another who he/she thought to be committing an offence.

The circumstances of each case will need to be considered very carefully.
against Those Committing Crime

Reasonable Force

A person may use such force as is reasonable in the circumstances for the purposes of:
self-defence; or
defence of another; or
defence of property; or
prevention of crime; or
lawful arrest.

In assessing the reasonableness of the force used, prosecutors should ask two questions:
was the use of force necessary in the circumstances, i.e. Was there a need for any force at all? and
was the force used reasonable in the circumstances?

The courts have indicated that both questions are to answered on the basis of the facts as the accused honestly believed them to be (R v Williams (G) 78 Cr App R 276), (R. v Oatbridge, 94 Cr App R 367).

To that extent it is a subjective test. There is, however, an objective element to the test. The jury must then go on to ask themselves whether, on the basis of the facts as the accused believed them to be, a reasonable person would regard the force used as reasonable or excessive.

It is important to bear in mind when assessing whether the force used was reasonable the words of Lord Morris in (Palmer v R 1971 AC 814);


"If there has been an attack so that self defence is reasonably necessary, it will be recognised that a person defending himself cannot weigh to a nicety the exact measure of his defensive action. If the jury thought that that in a moment of unexpected anguish a person attacked had only done what he honestly and instinctively thought necessary, that would be the most potent evidence that only reasonable defensive action had been taken ..."

The fact that an act was considered necessary does not mean that the resulting action was reasonable: (R v Clegg 1995 1 AC 482 HL). Where it is alleged that a person acted to defend himself/herself from violence, the extent to which the action taken was necessary will, of course, be integral to the reasonableness of the force used.

 

This may also help, as there is an explanation as to what reasonable force is (in the UK).
This particular explanation does focus more on dealing with an intruder.

Does the law protect me? What is 'reasonable force'?

Anyone can use reasonable force to protect themselves or others, or to carry out an arrest or to prevent crime. You are not expected to make fine judgements over the level of force you use in the heat of the moment. So long as you only do what you honestly and instinctively believe is necessary in the heat of the moment, that would be the strongest evidence of you acting lawfully and in self-defence. This is still the case if you use something to hand as a weapon.

As a general rule, the more extreme the circumstances and the fear felt, the more force you can lawfully use in self-defence.

What amounts to disproportionate force? I’ve heard I can use that.

The force you use must always be reasonable in the circumstances as you believe them to be. Where you are defending yourself or others from intruders in your home, it might still be reasonable in the circumstances for you to use a degree of force that is subsequently considered to be disproportionate, perhaps if you are acting in extreme circumstances in the heat of the moment and don’t have a chance to think about exactly how much force would be necessary to repel the intruder: it might seem reasonable to you at the time but, with hindsight, your actions may seem disproportionate. The law will give you the benefit of the doubt in these circumstances.

This only applies if you were acting in self-defence or to protect others in your home and the force you used was disproportionate – disproportionate force to protect property is still unlawful.

I’ve heard that I can’t use grossly disproportionate force. What does that mean?

If your action was ‘over the top’ or a calculated action of revenge or retribution, for example, this might amount to grossly disproportionate force for which the law does not protect you. If, for example, you had knocked an intruder unconscious and then went on to kick and punch them repeatedly, such an action would be more likely to be considered grossly disproportionate.

Do I have to wait to be attacked?

No, not if you are in your own home and in fear for yourself or others. In those circumstances the law does not require you to wait to be attacked before using defensive force yourself.

What if the intruder dies?
If you have acted in reasonable self-defence, as described above, and the intruder dies you will still have acted lawfully. Indeed, there are several such cases where the householder has not been prosecuted. However, if, for example:
having knocked someone unconscious, you then decided to further hurt or kill them to punish them; or
you knew of an intended intruder and set a trap to hurt or to kill them rather than involve the police,

you would be acting with very excessive and gratuitous force and could be prosecuted.

What if I chase them as they run off?

This situation is different as you are no longer acting in self-defence and so the same degree of force may not be reasonable. However, you are still allowed to use reasonable force to recover your property and make a citizen's arrest. You should consider your own safety and, for example, whether the police have been called. A rugby tackle or a single blow would probably be reasonable. Acting out of malice and revenge with the intent of inflicting punishment through injury or death would not.

Will you believe the intruder rather than me?

The police weigh all the facts when investigating an incident. This includes the fact that the intruder caused the situation to arise in the first place. We hope that everyone understands that the police have a duty to investigate incidents involving a death or injury. Things are not always as they seem. On occasions people pretend a burglary has taken place to cover up other crimes such as a fight between drug dealers.