Insanity

• When is this defence applicable?

  If D claims he was legally insane at the time of the alleged offence
• Affect?

  If jury decides D has committed a criminal offence he will be found 'not guilty by reason of insanity'.
• M'Naughten rules

  Elements

  1. Defect of Reasoning
  2. Arising from disease of the mind
  3. Causes to not to know nature or quality of his act or that his act was wrong
• Defect of Reasoning

  Must be impaired and not merely confusion or absentmindedness

  R v Clarke
• Test for DoR

  Was there evidence that D could reason with himself?
• R v sulivan

  Defects of Reasoning can be temporary
• Arising from disease of the mind

  Can be phyisical if it affects brain (R v Sulivan) or mental (R v Kemp)
• What must the disease of the mind be?

  An internal factor (R v Coley)
• Sleepwalking

  R v Burgess: 'sleep is a normal condition, but sleepwalking particularly violence in sleep is not normal'
• Hyperglycemia

  Can be a disease of the mind as caused by internal factor (R v Hennesy)
• Hypoglycemia

  Not a disease of the mind as is influenced by external factors (R v Quick)
• D not knowing nature of the act

  Either by;

  • Not being in state of consciousness / impaired (R v Kemp)
  • If conscious, D must not have understood what he was doing (R v Oye)
• Or D doesn't know the wrong in his act

  D must not have known that his act was legally wrong. If D knew he was wrong, not insanity (R v Windle)