What constitutes self-defence?

Written 12th September 2023 by Jack Tomlinson

What is self-defence?

Self-defence is a complete defence to all crimes and applies in circumstances whereby you are defending yourself from unlawful force, defending another, or even defending property. Self-defence also encompasses situation whereby a crime may be prevented or to allow for a lawful arrest. Whilst the law allows for you to defend yourself, you may only do what is reasonably necessary. This refers to using reasonable force in light of all the circumstances to defend yourself or another.

Reasonable force

For self-defence to be successful, the force used must be reasonable and two questions will be asked:
  1. Was the use of force necessary in the circumstances?
  2. Was the force used reasonable in the circumstances?
The court will take into account that having to use force to defend yourself is a terrifying prospect, so what matters is how you felt at the time in those specific circumstances. The second question is an objective element, as the jury must then go on to ask themselves whether, on the basis of the facts as you believed them to be, a reasonable person would regard the force used as reasonable or excessive.

Can I defend myself if someone breaks into my home?

A heightened version of self-defence applies to those facing intruders in their homes which is more lenient in terms of force that can be used. Guidance published by the CPS and National Police Chiefs Council makes clear that if householders have done what they honestly and instructively think is necessary in the heat of the moment, then this will be strong evidence to show that they have acted lawfully, in self-defence. The law allows for disproportionate force when someone is defending themselves against home intruders however, force will not be considered reasonable if it is “grossly disproportionate”. An example may be if you struck someone and they fell unconscious, continuing to strike or kick them would not be reasonable, and likely considered grossly disproportionate. Chasing someone off the property but continuing after them is unlikely to be considered as a continuing act of self-defence however, reasonable force can still be used to recover property or make a citizen’s arrest.

What if I hit someone first?

There is nothing in law to state that a person must wait to be hit first before defending themselves, however the court will still apply the above tests to make a determination that the use of force was necessary and reasonable in the circumstances.

Burden of proof

Where self-defence is raised by the defence, the prosecution must disprove it. The prosecution must satisfy a jury beyond reasonable doubt that you:
  1. Did not act to defend yourself or another; or
  2. Were not acting to defend property/prevent a crime/effect a lawful arrest; or
  3. If you were acting for the above, the force used was excessive.
Jack Tomlinson

Jack Tomlinson



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