The state government has announced plans to double the maximum jail sentence for one-punch killers from 10 years to 20 years.
WA's attorney general Michael Mischin announced the move on Saturday.
It involves making a change to section 281 of the Criminal Code which deals with the offence of unlawful assault causing death.
The Attorney General said that the offence was introduced in 2008 to deal with "one-punch homicides".
But the planned change in the law would come through the new Family Violence Bill so that the "one-punch" legislation will in future also apply to domestic violence cases where more serious charges could not be proved due to lack of witnesses.
Mr Mischin cited the case of Saori Jones, who died in 2010 after being punched by her partner. He was sentenced to five years in prison.
"The often abhorrent circumstances in which these assaults are committed and in how the victim dies has led the state government to the view that the current 10 year maximum penalty does not adequately reflect the gravity of the offenders' conduct, the value of the victim's life and the need to provide a sufficient deterrent," he said.
"Given that the penalty for manslaughter has been increased from 20 years imprisonment to life imprisonment, the government will increase the maximum sentence for the offence of unlawful assault causing death from 10 years to 20 years."
The Criminal Law Amendment (Homicide) Act 2008 was introduced in response to cases where an unlawful assault resulted in the death of the victim but where the attacker had escaped a conviction for any form of homicide.
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