Defensive Homicide was introduced by the Crimes (Homicide) Act 2005 section 9AD and was repealed on 1 November 2014 by the Crimes Amendment (Abolition of Defensive Homicide) Bill 2014. It was a relevant defence in relation to the charge of murder.
The defence only applies to offences committed on or after 23 November 2005 and before 1 November 2014.
The defence was originally created to cater for woman who were being domestically abused. It also provided offenders with mental illness leniency by the courts when they could not rely upon a mental impairment defence.
Notwithstanding parliament’s original intention, the defence was abolished because the defence was predominantly being relied upon by men who have killed other men in violent confrontations, often with the use of a weapon and often involving the infliction of horrific injuries’, which had led to ‘justifiable community concern that the law, like provocation once did, is allowing offenders to “get away with murder”, see this research paper for more information.
Section 9AD Defensive Homicide stated:
A person who, by his or her conduct, kills another person in circumstances that, but for section 9AC, would constitute murder, is guilty of an indictable offence (defensive homicide) and liable to level 3 imprisonment (20 years maximum) if he or she did not have reasonable grounds for the belief referred to in that section.
Defensive homicide was an alternative to the charge of murder in circumstances where self defence was not made out, that is, the jury could not be satisfied that the accused held a reasonable belief that it was necessary to kill another to protect themselves from the infliction of serious injury or death. In these circumstances it was open for the jury to find the accused was guilty of the lesser charge of defensive homicide.
An example would be where a victim is murdered while asleep and there is significant evidence of family violence which led the offender to commit the offence in such circumstances.
Essentially the defence is relevant when the accused had a belief that their actions were necessary for self defence, but the grounds for that belief were not reasonable.