All New Zealanders should have a right to defend themselves, their families and their property from criminals without being prosecuted, says the Act party.

Justice spokesman Stephen Franks yesterday announced the party's self-defence policy, which emphasises that the law should ensure criminals are afraid, not their victims. Mr Franks presented a medal to Auckland man Michael Vaimauga, who was arrested for assault after he stopped a burglar breaking into a shop.

Mr Vaimauga went through five court hearings before being discharged without conviction and ordered to pay $150 to the Salvation Army. The would-be burglar has never been charged.

"The state has no right to punish citizens for defending themselves and their property when the state cannot defend them," said Mr Franks.

The Vaimauga case symbolised the threat to people's right to make citizens arrests.

Mr Franks said the law once gave immunity to people to do whatever was necessary and reasonable to protect their families and property from criminals, but 25 years ago the defence of provocation was removed.

He said Act would introduce a provision requiring that the Attorney-General's leave would be necessary before a person could be charged, for example with assault, where that person was defending against a crime.

Act would amend the Crimes Act, Trespass Act and Arms Act so that protecting oneself or others against crime was a legal defence to a charge of using excessive force.

Mr Franks said the party would protect against open slather by denying the defence where the force used was disproportionate.