Three activists cleared by a jury after intentionally damaging a Government spy base committed an act akin to protecting al Qaeda and the Taleban, says an American security expert.

Ralph Cossa, president of the Pacific Forum Centre for Strategic and International Studies, told the Herald from Hawaii yesterday that he was disappointed but not shocked to hear of the decision of a Wellington jury to acquit the trio on charges of burglary and wilful damage at the Waihopai base near Blenheim.

Primary schoolteacher Adrian Leason, Dominican friar Peter Murnane and farmer Sam Land freely admitted they broke into the base in April 2008 and used sickles to slash and deflate an inflatable plastic dome covering a satellite dish.

They argued they believed they were acting lawfully because they were protecting people overseas who could come to harm through intelligence collected at the base and passed on to nations at war such as the United States.

Mr Cossa said of the court case: "It sounds more like an episode of Boston Legal in the US, than it does a real-life drama, to be quite honest."

Legal experts say that while it is an unusual case, there is no legal precedent stemming from the verdict, or anything that would give people "carte blanche" justification for attacking any other Government sites.

"Nothing has changed, except that a group of three defendants have persuaded a jury ... that the Crown had not proved beyond reasonable [doubt] that they did not honestly believe they were entitled to do this," said Law Society criminal law spokesman Jonathan Krebs.

The Crown is yet to decide if it will appeal.

Mr Cossa said he was surprised the defence mounted by the trio found resonance with a jury.

"It certainly seems that you could have made the counter-argument much more successfully [for] collecting intelligence which saved the lives of military forces, including New Zealand forces, who would be otherwise putting their lives at risk in order to defend their own country and the international community from terrorists.

"To say that fighting against the people who are fighting against the Taleban and al Qaeda equates to fighting for peace ... Essentially what you are saying is, 'We are trying to protect al Qaeda and the Taleban'."

Mr Leason rejected Mr Cossa's assessment, saying the only people the trio had been trying to protect were innocent civilians being killed in illegal wars.