You Aussies need to get together a plan for when you rewrite your constitution. You need to make sure that your right to defend yourself is protected as a "natural right". This crap about government giving you the privilege to live is hog wash. You need to educate people about their God given (natural) rights. The same rights that exist for all life forms on Earth.
If the government made a call for all those with a last name beginning with "S" to assemble at the curb so they could be shot to reduce over-population and make the world better for the children, would you do it? You are saying the government has the power and it would be a lawful act.
It's malarkey and governments don't have rights. The government gets its lawful power from the governed. If they are abusive the abused stand up and revolt. That has been true throughout the ages and the world. Make them recognize your right to live, to protect your life and property.
I'll even volunteer to write it for you.