Wellington, July 15 NZPA - Changing or repealing the "claim of right" defence successfully used by the Waihopai spy base saboteurs is an over-reaction to their acquittal, the Green Party says.

Justice Minister Simon Power said yesterday he was going to change or repeal the defence because it was being used in a way Parliament did not intend when the law was enacted.

In March three men, Peter Murnane, Sam Land and Adrian Leason, admitted attacking the spy base near Blenheim and were acquitted after it was argued they were driven by a belief that the station caused human suffering and their actions were lawful.

Mr Power said a preliminary report on the defence had identified five options, including its repeal.

He said his advice was that the courts had extended the claim of right defence beyond what was anticipated by Parliament when it was defined in the Crimes Act 1961, and when it was amended in 2003.

"It's clear it was not intended to be used to excuse the behaviour of people who take or damage property in cases where they are not claiming a personal property right," he said.

"Concern has been raised that the legislative scope of `claim of right' has become too broad and that the defence should not be able to be use it as it was in the Waihopai case, and I agree with that."

Mr Power said it appeared the law was out of step with comparable overseas jurisdictions including England, Canada and several Australian states.

The Green Party's human rights spokesman, Keith Locke, said there was a common sense justification for the "claim of right" defence.

"Most people would support someone breaking down a door if they believed someone inside was in distress -- even though damaging the door might technically be a crime," he said.

"The Waihopai three believed they were also helping people in distress. They offered proof that the Waihopai spy station has been used to spy on nations opposed to the disastrous war in Iraq."

Mr Power said he had asked officials to look at finding the best option to bring the defence back to what Parliament intended, to clarify its scope, to address issues specifically raised by the Waihopai case, and to bring it more into line with overseas jurisdictions.

The options Mr Power has are:

* Shifting the burden of proof -- amending the definition so a defendant would have to prove they have a claim of right rather than the prosecution needing to prove they do not;

* Adding a reasonableness element -- amending the definition of claim of right so a defendant would have to show that at the time of the offence their actions or beliefs were reasonable;

* Amending the offences that have claim of right as an element -- amending some or all of the 14 offences in the Crimes Act that have claim of right as an element to ensure the defence is not wider than is appropriate;

* Adding a property interest criterion -- amending the defence of claim of right so only a defendant with a legal claim to the property concerned could use the defence; and

* Repealing the defence -- remove the claim of right defence from the Crimes Act so it is not available to any defendant in future.