Self-Defence and Prevention of Crime

Self-defence in English law derives from two sources: the common law right to use reasonable force in defence of oneself or another, and s.3 Criminal Law Act 1967, which permits the use of reasonable force in the prevention of crime or the effecting of a lawful arrest. Section 76 of the Criminal Justice and Immigration Act 2008 (CJIA 2008) clarifies the operation of both defences without replacing them.

If self-defence succeeds, it provides a complete defence resulting in acquittal — there is no partial defence reducing murder to manslaughter (unlike loss of control). The defence is available to all offences against the person, from common assault to murder.

The defence involves a two-stage test:

Stage 1 — Was the use of force necessary? The defendant must have honestly believed that the use of force was necessary. Under s.76(3) CJIA 2008, the question is assessed on the facts as the defendant genuinely believed them to be, whether or not that belief was reasonable. An unreasonable but genuine belief will suffice (R v Williams (Gladstone) [1987] 3 All ER 411). However, a mistaken belief induced by voluntary intoxication cannot be relied upon (s.76(5)).

Stage 2 — Was the degree of force reasonable? The force used must be objectively reasonable in the circumstances as the defendant believed them to be (s.76(3)). In Palmer v R [1971] AC 814, Lord Morris stated that a person defending himself "cannot weigh to a nicety the exact measure of his necessary defensive action." The jury should consider whether the defendant did only what they honestly and instinctively thought was necessary in the heat of the moment.

There is no duty to retreat before using force in self-defence (s.76(6A) CJIA 2008). However, the possibility of retreat is a factor the jury may consider when assessing the reasonableness of the force used. In R v Bird [1985] 1 WLR 816, the Court of Appeal confirmed that a demonstration of unwillingness to fight is not a prerequisite of the defence.

A defendant may also use pre-emptive force — they need not wait to be struck first. In R v Beckford [1988] AC 130, 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."

Section 43 of the Crime and Courts Act 2013 (inserting s.76(5A) CJIA 2008) introduced a more generous test for householders who use force against intruders. In householder cases, the force used is not to be regarded as reasonable if it was grossly disproportionate, but force that is disproportionate (but not grossly so) may still be reasonable.

A "householder case" requires: (1) the force is used by the defendant while in, or partly in, a building that is a dwelling; (2) the defendant is not a trespasser; and (3) the defendant believed the victim to be a trespasser. In R v Ray [2017] EWCA Crim 1391, the Court of Appeal confirmed that the householder defence applies only inside the dwelling, not in the garden or driveway.

If the defendant uses excessive force, the defence fails entirely. Unlike Australian law (Zecevic v DPP (Victoria) [1987] HCA 26), English law does not recognise a partial defence of excessive self-defence reducing murder to manslaughter. This was confirmed in R v Clegg [1995] 1 AC 482, where a soldier who fired a final shot at a car that had already passed through a checkpoint was convicted of murder.

However, the loss of control defence under ss.54-56 Coroners and Justice Act 2009 may be available where the defendant lost self-control due to a fear of serious violence, even if the force used was excessive for self-defence purposes.