There must also be proof that the actions of the accused were what caused the victim’s death.
The prosecutor has to prove that the actions of the accused were committed despite knowing that his actions will probably cause grave bodily injury to or the death of the victim but the accused still persisted showing his intent to harm and kill the victim.
From the discussion above, it is clear that there is a requirement that the accused must have full possession of his mental faculties in order to have the criminal intent necessary to commit murder. The accused must fully understand that causing another human being to sustain grave bodily injury that would probably cause his death is morally and legally wrong. Despite this knowledge, the accused still persisted and caused the victim’s death.
If the accused did not have the necessary criminal intent -- if he did not have sufficient understanding that his actions were morally or legally wrong, or that his actions may cause the victim’s death then the accused cannot form the specific criminal intent necessary to commit murder.
To avail of the partial defence of abnormality of mind, however, the accused must not only prove that he did not have the criminal intent necessary to commit murder, he must also prove that his inability to form the criminal intent is because of an underlying medical or psychiatric condition.
The medical or psychiatric cause must be such that it caused an arrested or retarded development of his mind. This impairment of the mind of the accused will be enough to mitigate his criminal liability from murder to homicide.
Why is abnormality of mind due to an arrested or retarded development of mind only a partial defence to murder? The accused who employed this defence actually admits the killing only that he interposes a legal excuse to mitigate his responsibility. This is why the defence of abnormality of mind only provides a partial defence and it only works to mitigate the conviction from murder to homicide.
The benefit of this partial defence is that the accused will not be convicted of a capital offence and, there is a possibility that the accused can receive treatment for his mental infirmity.
Disclaimer : This article is just a summary of the subject matter being discussed and should not be regarded as a comprehensive legal advice for you to defend yourself alone. If you are charged with criminal offences, it is recommended that you seek legal assistance from criminal lawyers.