Can You Legally Kill Someone in Self-Defence?

Man in handcuffs

When does killing in self-defence become murder, and what are the laws about defending your property?

The extent to which a person can defend themselves or their property against a would-be attacker is often the subject of intense debate, particularly when a related news story breaks. A good example of this arose in 2018, when 78-year-old Richard Osborn-Brooks was arrested on suspicion of murder after killing an intruder to his home.

Much of the commentary surrounding the case was critical of the decision to arrest Mr Osborn-Brooks, arguing that his actions were taken in legitimate self-defence. Comparisons were made to the case of farmer Tony Martin, who was famously convicted of murder (later reduced to manslaughter) in 1999 for fatally shooting an intruder to his home.


Homeowners do indeed have the right to defend themselves and their family from intruders if they believe their lives are in danger. In fact, in England and Wales, we allow people to use ‘reasonable force’ to defend themselves, someone else, or their property.

The question of what constitutes ‘reasonable force’ is often where the difficulty lies in cases such as these.

According to current law, when defending ourselves or another, we are permitted – for example – to punch someone who we believe is about to punch us. However, it would not be considered reasonable to stab someone who was merely about to punch us or someone else.

In relation to defending property – including our homes – the principles are similar. Reasonable force can be used, according to the circumstances as the defendant believed them to be at the time.


In most cases, the police can interview those involved in a crime on a voluntary basis.

However, in this case (particularly as a death was involved), the police are likely to have wanted to search Mr Osborn-Brooks’ house for evidence. In order to do so they would need to arrest him so that they would have the power to search under section 18 of the Police and Criminal Evidence Act 1984.

It is important here to differentiate between arrest, charge and conviction. Mr Osborn-Brooks’ arrest simply meant that the police suspected that he may have murdered somebody. It did not mean that he would be charged, and certainly did not mean that he would be convicted.


The fact that Mr Osborn-Brooks was arrested under suspicion of murder, rather than manslaughter, was also been a point of controversy amongst commentators on this case.

In this context, manslaughter only exists as a partial defence to murder. For someone in Mr Osborn-Brooks’ position to be convicted of murder, the prosecution would have to prove that he either intended to kill the burglar, or cause him really serious harm. If the jury thought that he had intended to merely harm him, then they would convict him of manslaughter in the alternative.

Therefore, although a jury might convict a defendant such as Mr Osborn-Brooks of manslaughter, it is right the police treat the incident as possible murder.

It would be for a jury to decide whether he intended to kill the burglar, or was simply negligence about the risk. If the former, then it will be murder. If the latter, then it would be manslaughter. If the jury thought he had acted reasonably then he would be acquitted altogether.

In this case, Mr Osborn-Brooks was ultimately cleared of all charges and faced no further action. However, much like the high-profile case of Tony Martin back in 1999, it certainly prompted considerable debate about the rights all of us have to defend ourselves from harm.

Find out more about our criminal defence and advocacy services
Regan Peggs
Latest posts by Regan Peggs (see all)