Self-Defence, what can I do legally?

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Use of reasonable force for self-defence

When teaching self-defence classes I am often asked about what techniques to use, the question should really be twofold, firstly how much force can I use in my defence (Reasonable Force) and secondly do I need to wait for them to strike first (Use of pre-emptive strike).

Hopefully I will try to answer both questions for you.

Lawful definition of self defence

The following is taken from the Crown Prosecution website.

“It is both good law and good sense that a man who is attacked may defend himself. It is both good law and good sense that he may do, but only do, what is reasonably necessary.”

“A person may use such force as is reasonable in the circumstances in the prevention of crime, or in effecting or assisting in the lawful arrest of offenders or suspected offenders or of persons unlawfully at large.”

A person may use such force as is reasonable in the circumstances for the purposes of (in the alternative): –

  • self-defence;
  • defence of another;
  • defence of property;
  • prevention of crime;
  • lawful arrest.

Self-Defence and the Prevention of Crime | The Crown Prosecution Service (

What types of offences are there?

Starting with the use of force, you may be familiar with certain offences that involved the use of force such as;

  • common assault and battery (just means that there’s some physical contact),
  • this escalates into a section 47 assault where there’s a higher degree of injury such as some bruising or such

and that then it escalates into GBH (Grievous Bodily Harm) which is more seriosu form of assault where there is a more serious injury such as broken bones.

So what if I am attacked?

So if you are attacked and you end up inflicting harm on someone else in your defence it’s important for you to state that “you acted in self-defence”, in other words you tell the police that you were acting in self defence.  You do not have to prove it was in self defence you only have to raise it as self defence.

In doing this if it goes to court it is for the other side (prosecution) to firstly demonstrate that the you were not acting in self defence, i.e. there was not a genuine belief (on your part) of the circumstances (it doesn’t matter if you are mistaken in your belief nor if an onlooker believed differently), its your belief that counts  and secondly that you did not use reasonable force i.e. you used excessive force.

So for example if you were attacked and used a knife to defend yourself against an unarmed attacker this would likely be seen as excessive force.

If it was dark and you thought you saw the attacker with a knife and defended yourself with a stick or metal bar this might be seen as reasonable force given the attacker had escalated the situation by using a weapon, even if the knife turned out to be something else, so long as you genuinely believed it was a knife.  

Do I have to wait for them to strike before I defend myself?

It is also permissible for you to strike first if you feel threatened, this is what is termed as a per-emotive strike.  So for example if someone comes at you in a threatening way, shouting and gesturing in an aggressive manner, maybe threatening you, then you have the right to strike first in order to prevent yourself from being attacked you do not need to wait to be hit first before defending yourself likewise if you are defending your home you don’t need to wait to find out that they’re a burglar before you defend your home so long as again you hold a genuine belief and the magistrate with jury finds that your use of force was reasonable given those circumstances.

What about if I have been drinking?

If you are voluntarily intoxicated through drink or drugs then you cannot rely on this genuine belief of the circumstances because your perception and awareness will be impaired.


It is important firstly to understand you do have a right to defend yourself and that the response should be proportionate, it should also be understood that the law does change and you should be aware of that, at the time of writing this is correct but could change at some point, although I suspect it would not change but rather be clarified further.

I hope you enjoyed this blog, feel free to give me feedback in the comments below.

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