H418/01 - Self-defence and evaluation

Defensive purpose and the burden

Self-defence can justify force used to protect yourself or another person. The common law also protects property; section 3 of the Criminal Law Act 1967 permits reasonable force in preventing crime or effecting or assisting lawful arrest. Section 76 of the Criminal Justice and Immigration Act 2008 clarifies the operation of the relevant defences, including reasonableness.

A justified use of force is lawful. Self-defence can therefore be a complete defence even to murder, rather than merely reducing murder to manslaughter. Compare the partial homicide defences: their function is different.

The central questions are:

1. Did the defendant honestly believe force was necessary in the circumstances as they understood them?
2. Was the degree of force reasonable in those believed circumstances?

The first concerns belief; the second imposes a legal standard on the response. “I was frightened” is evidence, not the complete defence. Force used to punish someone after danger has ended is revenge, rather than necessary protection. A person cannot obtain a licence for violence by calling it crime prevention; the legal requirements of the particular defence must be met.

The defendant must raise sufficient evidence of self-defence for it to be considered. Once properly raised, the prosecution must disprove it beyond reasonable doubt. It can do this by establishing that there was no honest defensive belief or that the force was unreasonable. The defendant does not carry the insanity defence’s burden of proving the defence on the balance of probabilities.

Necessary force and mistaken belief

Necessity is judged against what the defendant honestly believed was happening. A defendant need not wait to be struck before defending themselves against an attack they honestly believe is imminent.

Beckford v R (1988) recognises that a person facing an imminent attack can use a pre-emptive response. R v Williams (Gladstone) (1984) involved intervention in what the defendant mistakenly thought was an assault. The important rule is that an honest mistake can support the defence, even if it was unreasonable. Section 76(4) preserves this approach. Whether the belief was reasonable remains evidence of whether it was truly held; the court need not accept an implausible story simply because it is asserted.

Section 76(5) excludes a mistaken belief attributable to voluntary intoxication. A sober person who honestly mistakes a raised metal tool for a weapon presents a different case from someone whose deliberate drug use creates a paranoid belief in an imaginary attack. R v Taj (2018) confirms that a mistake directly and proximately resulting from voluntary intoxication can be excluded even after the intoxicant itself is no longer present. Mere intoxication does not eliminate self-defence where a real attack and otherwise lawful response occur.

There is no strict duty to retreat. Section 76(6A) makes the possibility of retreat a factor in assessing reasonableness rather than an absolute condition. A safe route away can matter; refusing it does not automatically settle the case. These rules recognise that people may have little time and incomplete information, while leaving the truth of the belief open to scrutiny.

Original example: Han sees a stranger raise a heavy object towards Han’s friend and pushes the stranger away. A credible honest belief in an imminent blow may establish necessity, although later evidence shows the stranger was passing the object. If Han knew the object was being passed and pushed out of anger, necessity fails.

Reasonable force in the believed circumstances

The degree of force is judged objectively against the circumstances the defendant honestly believed. It is not whatever degree that particular defendant considers acceptable.

In Palmer v R (1971), the court recognised that a person under attack cannot be expected to calculate the exact defensive response with precision. Section 76(7) reflects this: evidence that a person did only what they honestly and instinctively thought necessary is strong evidence of reasonable action. It is not conclusive permission to use any force.

In ordinary, non-householder cases, section 76(6) excludes disproportionate force. Relevant facts include the perceived attack’s seriousness, weapons, numbers, relative positions, how long force continued and whether danger was ending. A push to stop an imminent punch may be reasonable. Continuing to strike a person lying motionless after the perceived threat ends is much harder to justify.

R v Clegg (1995) shows the consequence of excess in a murder case. A soldier fired at a passing vehicle; the fatal shot occurred after it had passed, when the danger was over. Excessive force did not create a partial self-defence reducing murder to manslaughter. If the prosecution proves murder’s elements and defeats self-defence, the murder conviction follows, subject to any other applicable defence. Do not assume every unsuccessful defence automatically means murder: the offence must independently be proved.