General Defences

A two part test for this was laid down in R v Graham:

• Was D forced to act as he did because he feared death or serious physical injury?
• Would a sober person of reasonable firmness, sharing the characteristics of D have responded in the same way?

Threatening to disclose something about D is not covered (R v Valderrama-Vega). The threat must be directed towards D or a person for whom he has responsibility (R v Hasan). There must be an imminent threat of harm, so no safe means of escape (R v Gill). If D believes there is an imminent threat, this is sufficient.

R v Bowen set out the characteristics of D that can be taken into account: age and gender, pregnancy, serious physical disability, recognised mental illness or psychiatric disorder.

Self-induced duress is not sufficient, such as where D joins a criminal gang, or puts himself in a position where he knows he is likely to be subjected to threats of violence or actual violence (R v Shepherd / R v Heath). 

There is no direct threat but the circumstances threaten death or serious injury if D does not commit a crime.

This cannot be used as a defence for murder or attempted murder (R v Pommell).

The circumstances are judged as D believed them to be (R v Cairns).

R v McNaghten states that everyone is presumed sane so the burden is on D to prove that they are not.

D must have been suffering from a defect of reason, which is an inability rather than a failure ~ 'could not' rather than 'did not' (R v Clarke).

The defect must be caused by a disease of the mind. This could be a permanent or temporary state, and this must be an internal factor (R v Bratty / R v Burgess / R v Kemp).

D must have been unable to either know the nature and quality of their act (R v Codere), or not know what they were doing was wrong (R v Windle).

D's actions must have been involuntary ~ D's mind was not controlling his body in a 'purposeful manner' (R v Bratty). A total lack of awareness is required, so the defence is difficult to prove (A-G's Ref (No. 2 of 1992)).

It must have been caused by an external factor (e.g. a head injury or drugs).

The defence is not available for self-induced automatism (e.g. through excessive drinking or taking illegal drugs), but if D has a strange reaction to prescription, the courts will consider if D knew he had a risk of getting into that state (R v Hardie).

D must be unable to form the mens rea due to intoxication (R v Kingston).

The defence is available only to specific intent crimes (e.g. murder and GBH S18), not basic intent crimes where recklessness is part of the mens rea, because becoming intoxicated fulfils the recklessness element (R v Majewski).

If intoxication is involuntary, then the defence is allowed for both types of offence provided D lacked the mens rea. Involuntary intoxication can be through prescribed drugs, soporific drugs, or spiked drinks (R v Hardie). 

Not realising the strength of the drink is not a defence (R v Allen). 

Was the consent genuine? V must be of age, of sound mind, and have sufficient understanding and intelligence to give consent (Burrell v Harmer). V must be aware of all the circumstances, so a mistaken belief or fraud will prevent genuine consent (R v Tabassum).

Is the nature and degree of harm allowed? V can consent to 'socially useful', minor harm such as an assault or battery, but not to serious harm or death (R v Brown / R v Wilson).

Self defence is a common law defence where you attack someone who has attacked you or you think is going to. It also applies to protection of another person or property.

Prevention of crime is contained in S3 Criminal Law Act 1967, allowing reasonable force to be used to prevent crime, or lawfully arrest suspected offenders.

Was the force used necessary? There must be an imminent threat of harm (R v Malnick).

If D had a mistaken belief, then the facts will be assessed as D believed them (R v Williams).

Was the force used reasonable? The amount of force used must be proportionate to the level of threat that was perceived. S76 Criminal Justice and Immigration Act 2008 states that D must have done "what they honestly and instinctively thought was necessary" (R v Clegg / R v Martin).