Discuss the defence of self defence and prevention of crime
A concept of reasonable self defence (private defence) has developed through common law. There is statutory law covering public defence, in relation to prevention of crime (S3 of the Criminal Law Act 1967).
There is overlap between the two although self defence may be used against someone who is not actually committing a crime, for example if perpetrator is insane.
Necessity of force
The first question is whether the force was necessary, the general principle is that the use of force is not justified. Necessity of the force is decided by the jury.
Use of force can be found necessary if it is seen to be so in the situation that exists or that the defendant believes exists.
Defendant saw a man struggling with a youth who was calling for help and intervened, in fact, the man was affecting a lawful arrest of the youth. Defendant found not guilty of assault (Gladstone Williams (1987)).
There is a statutory basis to defence for defendants who genuinely hold a mistaken belief. S5 of the Criminal Justice and Immigration Act 2008 sets out that this does not necessarily apply if defendant is voluntarily intoxicated.
Pre emptive action
Defence can also apply to an imminent attack.
Withdrawing or demonstrating an unwillingness to fight can be used as evidence that the defendant is acting reasonably and in self defence. However, there is no absolute obligation to retreat (Bird (1985)).
Lord Griffiths stated
.. a man about to be attacked does not have to wait for his assailant to strike the first blow, or fire the first shot, circumstances may justify a pre-emptive strike... (Beckford (1988)).
Reasonableness of force
A jury must decide if the force used was reasonable.
Lord Morris stated
.. it is both good law and good sense that a man who is attacked may defend himself... he may do, but may only do what is reasonably necessary...(Palmer (1971)).
A soldier shot and killed a car passenger. A car came towards a soldier at speed when he was stationed at a checkpoint. Evidence proved the shot which killed the victim had been fired once the car had passed, so there was no argument for self defence. A conviction for murder was upheld on appeal (Clegg (1995)).
Unreasonable force may not be used (Martin ).
S76 of the Criminal Justice and Immigration Act 2008 recognises that someone under attack is under stress so may not be able to reason as precisely.