The use of force against intruders – the blurry lines of ‘lawful killing’

8 May 2019

Last week, a Senior Coroner recorded a verdict that homeowner Mr Osborn-Brooks ‘lawfully killed’ an armed burglar with a kitchen knife.  The burglar himself was armed with a screwdriver, leading Mr Osborn-Brooks to believe that he “intended to do [him] harm”, and thereby leading the Coroner to conclude that Mr Osborn-Brooks acted in self-defence. This blog considers the blurry lines underpinning the law of self-defence in the context of home intruder cases and the potential challenges these pose. 

The basic principles

In assessing the reasonableness of the use of force in self-defence cases, the questions to be answered are whether the force was both ‘necessary’ and ‘reasonable’ in the circumstances.  This test may seem somewhat circular, but while it contains an objective element, it also requires subjective consideration of what the Defendant honestly believed the circumstances to be at the time (section 76 of the Criminal Justice and Immigration Act 2008). 

The use of force in householder cases

In 2013, the 2008 Act was amended to include a heightened defence for ‘householder’ cases – i.e. where self-defence is used by a homeowner against a person who is believed to be in, or entering, that person’s property as a trespasser.  These provisions apply to trespassers ‘in or partly in’ a place of residence (including houseboats and caravans).  They do not apply where the trespass takes place wholly outside the building (i.e. in the garden), and the homeowner him/herself must not be a trespasser (i.e. a squatter).  (See Crown Prosecution Service (CPS) guidance). 

Further guidance issued by the CPS sets out where heightened protection will be afforded to homeowners who have acted “reasonably” and “honestly and instinctively and in the heat of the moment” to defend themselves or another person (and, only where the force is ‘reasonable’, to protect or recover property or to make a citizen’s arrest).  Helpfully, the guidance states that if a homeowner is using something to hand as a weapon, it can still be considered reasonable, depending on the circumstances.  It also states that, as a general rule, the more extreme the circumstances and fear felt, the more force you can lawfully use in self-defence. 

The 2008 Act provides that those using force to protect themselves or others can use a degree of force which may in hindsight be considered disproportionate in the circumstances, but may still be considered lawful (so long as it was reasonably believed to be necessary).  For example, if the circumstances were “extreme” and the homeowner is acting in the “heat of the moment”, and does not have time to properly contemplate how much force would be necessary.  In such circumstances, the CPS guidance confirms that “the law will give you the benefit of the doubt”.   

A homeowner does not need to wait until he/she is attacked.  So long as they are in their own home and fear for their safety, or for the safety of others, it will be considered lawful to use reasonable force against that intruder.  Importantly, this heightened defence of ‘disproportionate force’ is not applicable to homeowners protecting their property (for which, see below).

However, actions that are considered to constitute ‘revenge or retribution’ will be considered grossly disproportionate and will not be protected under the law.  Examples given by the CPS are where an intruder has already been knocked unconscious and the homeowner then goes on to kick and punch the intruder, or where the homeowner knew of an intended intruder and set a trap to hurt or kill them, rather than calling the police.  In such circumstances, the homeowner will be deemed to have been acting with “very excessive and gratuitous force” and could face prosecution. 

Protecting property

The heightened defence above does not apply to homeowners protecting their property, for which only reasonable force can be used.  CPS guidance on what may be considered ‘reasonable’ includes a “rugby tackle or a single blow”.  As an example of what would not be reasonable, see this case in which two men were convicted in 2009 after chasing after burglars who had already fled their property. 

In practice

The case of Mr Osborn-Brooks has interesting parallels with the infamous prosecution of Tony Martin, the farmer who shot a teenage boy in the back as he tried to burgle his farmhouse.  Mr Martin was found guilty of murder and sentenced to life imprisonment, although this was later reduced on appeal to manslaughter and five years’ imprisonment. 

This case took place in 2000, long before the law on ‘householder’ cases was introduced.  However, even applying the new law to Mr Martin’s case, it is arguably unlikely to have resulted in a different outcome given that he had laid booby traps in anticipation of a burglary.  Under the examples provided by the CPS, this would likely be an example of “grossly disproportionate” behaviour and would therefore fall foul of the law. 

The key distinguishing factor between this case and that of Mr Osborn-Brooks is that during the course of the burglary of Mr Martin’s property, no direct threat appears to have been made against him (compared to Mr Osborn-Brooks, who was threatened with a screwdriver). 

While the case of Mr Osborn-Brooks has generated much publicity, there has been little disagreement with the decision not to prosecute him.  This perhaps reflects the seemingly clear cut facts, which would likely have afforded Mr Osborn-Brooks a defence even without the change in the law.  It is a difficult area however, and there will doubtless be future cases that will test exactly how far householders are able to go in order to protect themselves or others.  In particular, cases where self-defence is used despite an absence of any threat over and above the presence of a trespasser in the home, and specifically those in which self-defence takes the form of serious violence, will present a challenge for police and prosecutors.

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