Public & Private Defence
Defence of Persons
Establishing the Defence of Persons
The defendant has a defence to any offence involving the use of force if he used necessary and reasonable force to defend himself or another: R v Yaman  EWCA Crim 1075. This defence is not available where a person uses force knowingly to prevent themselves from being lawfully arrested by a police offer: R v Browne  NI 96.
When is Force Necessary or Reasonable?
Force is necessary if a reasonable person would have used force. The reasonable person has the same beliefs about the circumstances and level of danger as the defendant: R v Shaw  1 Cr App 10.
Force is reasonable if a reasonable person with the defendant’s factual beliefs would have used that level of force. The force used must not be disproportionate in the circumstances as the defendant believed them to be: Criminal Justice and Immigration Act 2008, s 76(6).
Whether force is necessary and reasonable is assessed according to the circumstances as the defendant honestly believed them to be. This is true even if this belief is not reasonable: Criminal Justice and Immigration Act 2008, s 76(4). Facts which the defendant was unaware of cannot be relied on: R v Dadson (1850) 2 Den 35.
There is an exception to this rule where the defendant mistakenly believes something because he is voluntarily intoxicated: s 76(5). If the defendant makes a mistake because he is voluntarily intoxicated, he cannot rely on the mistaken belief.
The focus is on whether the use of force was reasonable. It is therefore not relevant that the force had some unexpected consequence, such as killing the victim: R v Keane  EWCA 2514.
It is relevant to whether force was reasonable and necessary that the defendant could have retreated, though he is not under a formal duty to retreat: Criminal Justice and Immigration Act 2008, s 76(6A).
A person acting instinctively for legitimate purposes may not have time to weigh up and think through a given course of action, and should not be expected to: Criminal Justice and Immigration Act 2008, s 76(7).
When determining the level of danger the defendant perceived, the jury may take into account the defendant’s physical characteristics: R v Martin (Anthony)  EWCA Crim 2245.
The Relationship Between Defence and Insanity
Generally, the jury cannot take into account the defendant’s psychiatric abnormalities: R v Martin (Anthony)  EWCA Crim 2245. Insane delusions cannot be attributed to the reasonable person when determining whether the force used was reasonable and proportionate: R v Oye  EWCA Crim 1725. The argument for this is that the defendant should be relying on the defence of insanity instead.
Some cases have allowed psychiatric evidence to be considered by the jury. This was were the evidence related to whether the defendant thought it was necessary to use force in the first place, rather than whether the level of force used was reasonable: R v Press  EWCA Crim 1849; R v Ibrahim  EWCA Crim 121. The law is somewhat unclear on when mental characteristics may be taken into account, as a result.
Preemptive Defence and Provoked Attacks
Even if the victim has not yet attacked the defendant, preemptive force may still be necessary and reasonable so long as the defendant anticipates an imminent attack: Devlin v Armstrong  NI 13; R v Beckford  3 All ER 425.
However, a defendant cannot rely on self-defence where they deliberately provoked the victim as an excuse for violence: R v Mason (1756) Fost 132. A person who starts a fight is still entitled to defend themselves if the victim goes beyond self-defence and escalates the fight, however. For example, the defendant might be expecting a fist fight but the victim draws a knife. It is still the case that the defendant cannot rely on self-defence if they provoked violence intending that it would escalate: R v Rashford  EWCA Crim 3377; R v Harvey  EWCA Crim 469.
A householder case is one where the defendant:
- Relies on self-defence inside or partially inside a dwelling or other accommodation (or part of a building internally accessible from these locations);
- Is not a trespasser; and
- Honestly believed the victim was in or entering the building as a trespasser: Criminal Justice and Immigration Act 2008, s 76(8A).
There is no need for the defendant to be the homeowner: R v Day  EWCA Crim 1646.
In householder cases, the degree of force used is not to be regarded as reasonable in the circumstances as the defendant believed them to be if it was grossly disproportionate: s 76(5A). Force which is not grossly disproportionate may still be unreasonable in the circumstances, however: R v Ray  EWCA Crim 1391. This seems to imply that disproportionate force can be reasonable in householder cases, though not in all householder cases.
Arrest & the Prevention of Crime
It is a defence to use necessary and reasonable force ‘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’: Criminal Law Act 1967, s 3(1).
In both cases, the same rules described above apply to determine if the force is necessary and reasonable: R v Morris  EWCA Crim 436.
There must be a link between the use of force and an imminent or immediate crime which the defendant believed he was preventing by using force: R (DPP) v Stratford Magistrates Court  EWHC 1794 (Admin). Private citizens are generally expected to call the police to prevent the crime if they can.
Since taking property without consent is a criminal offence, defence of property may fall under the defence of preventing crime. If the offence is criminal damage, however, normally the more appropriate defence is section 5 of the Criminal Damage Act 1971: R v Jones  UKHL 16.