The public and private defence referred to as self-defence provides a complete defence where the defendant uses force to protect their public or private interests. There are elements required for self-defence to be successful which will be discussed to advise ISL and relating to the cases.
Self-defence under section 3 Criminal Law Act states: ‘’a person may use such force, as is reasonable in the circumstances in the prevention of crime, or in effecting or assisting the lawful arrest of offenders or suspected offenders’’. The person must believe that he was about to be subjected to unlawful violence (imminent attack) and that he responded by using reasonable force to stop the attack which he predicted. In Beckford a police officer shot and killed a man escaping from a house. It was declared that the deceased was unarmed and had in fact surrendered before the defendant shot. However, the defendant insisted that he honestly believed that he was in danger, and thus was entitled to the defence. As the test for self-defence is one may use such force which is reasonable in the situation, as he honestly believes them to be in defence of himself or another. As such, the killing was not unlawful because he used reasonable force to defend himself as he feared for his own life. But if ISL were to attack, it does not need to be imminent. In Cousins, a threat to kill another person to prevent them from committing crime may be lawful under self-defence.
The two core elements that ISL should be aware of are trigger and response. Trigger is where the defendant must have believed that force was immediately required in order to protect her public/private interests. Hence, is it necessary to use any force against the victim. The element is subjective as stated in Criminal Justice Immigration Act (CJIA) s 76(3) whether it was necessary on the facts as D believed them to be. Also, issues of mistake specified in CJIA s 76 4(b) if the defendant claims he held particular belief in regard to circumstances, and generally did hold it and relies on it, even if it was a mistake it is a reasonable mistake to be made, recognized in Gladstone v Williams. Secondly, response is where the amount of force used by the defendant (D) must have been reasonable on the proof as D believed them to be, which is objective. In Beckford Lord-Griffiths stated ‘’a man about to be attacked does not have to wait for his assailant to strike the first blow, circumstances may justify a pre-emptive strike’’. Also, ‘’it is essential of all crimes of violence that the violence or threat should be unlawful’’. Therefore, to use self-defence ISL need all the elements in order to protect themselves or property.
Additionally, the question is whether the defendant’s belief in necessity of force was honest. The trigger element is not purely subjective, two objective considerations are: voluntary-intoxication and mental defects. Where the accused’s mistake whether to use any force or degree of force was caused by voluntary intoxication, the defence will fail. Criminal Justice and Immigration Act (CJIA) 2008 s 5 does not enable the defendant to rely on any mistaken belief to intoxication that was voluntarily induced. Also, mental defects caused by a defect or disorder. In Martin the defendant was not able to rely on psychiatric evidence that he perceived threats to be greater, than a normal/rational person would. Also, Lord Griffiths in Beckford states the ‘’genuineness of belief does not depend on seriousness of the psychiatric condition which might have given rise to it’’. Therefore, mental defects and intoxication will cause the defence to fail thus ISL cannot rely on these.
Furthermore, in Rashford he intended to attack the victim for revenge because of an earlier dispute. But the victim’s friends responded with aggression, and the defendant decided to plea self-defence instead. The court ruled the question was whether the retaliation was such that the defendant was allowed to defend himself. That depended on whether the violence offered by the victim was so out of ratio to the defendant's own act, as to give rise to the reasonable apprehension that he was in immediate danger and had no means of escape. Therefore, whether the violence which he used was no more than reasonable/necessary to protect himself from serious injury or preserve his own life, he would be entitled to self-defence. Henceforth, ISL must know the force used must be necessary and reasonable in circumstances, if unreasonable the defence will fail and if it is not immediately necessary. If the jury conclude that the degree of force which the accused used was excessive, the use of force will not be unlawful. But, this involves a margin of appreciation for the defendant recognising where one was pressured and in a stressful situation, she/he may not have been able to think rationally about the level of force used.
Initially ISL should know for the common law defence to succeed the defendant would have to establish that he had first retreated from the offered violence. In Julien it was stated that he required only 'to demonstrate that he is prepared to temporize and disengage and perhaps to make some physical-withdrawal'. The Julien case addressed what should and must be done, as the defendant must ‘demonstrate by his actions that he does not want to fight’. The criteria to assessing whether the defendant had used reasonable force, was that the force used to repel the attack must be in proportion to the force from the attacker.
To conclude, the prosecution must prove the case beyond all reasonable doubt and the defendant does not have the burden of proof in launching his defence. Hence, the jury must determine whether the circumstances were acceptable in assuming that an attack was imminent, therefore ISL must know all elements of self-defence in order to plea when threatened or to protect.
Written by Zahra Javed
 Criminal Law Act 1967 s 3
 John Child, David Ormerod, Essentials of Criminal Law, (2nd edn, OUP 2017) 588
 Beckford v R  1 AC 130
 (n2) 586
 R v Cousins  CA
 (n2) 585
 Criminal Justice Immigration Act 2008 s 76(3)
 Ibid s 76 4(b)
 Gladstone v Williams  78 Cr App R 276
 Crown Prosecution Service, ‘’Self-defence and prevention of crime’’ 2017 > https://www.cps.gov.uk/legal-guidance/self-defence-and-prevention-crime> accessed 1st March 2019
 (n3) (Lord Griffiths)
 (n2) 586
 Michael Allen, Textbook on Criminal Law, (9th edn, OUP 2007) 203
 (n7) s 5
 Martin  EWCA Crim 2245
 (n3) (Lord Griffiths)
 Rashford  EWCA Crim 3377
 Alan Reed, Peter Seago, Criminal Law, (Sweet and Maxwell 1999) 211
 William Wilson, Criminal Law, (1st edn, Longman Limited 1998) 291
 (n13) 206
 (n2) 589
 G R Douglas, ‘’Criminal Law – The changing nature of self-defence’’ (1988) Law Society Guardian Gazette, 20
 Julien  1 WLR 839
 Boaz Sangero, Self-defence in Criminal Law, (Hart Publishing, 2006) 199
 (n24) 21