Infamously, former Telecom chief executive Theresa Gattung once admitted her company used confusion as a marketing tool. For quite some time, it worked.

A similar strategy employed by three men who broke into the Waihopai spy base near Blenheim in 2008 and slashed an inflatable plastic dome covering a satellite dish has enjoyed equal success. Various wishy-washy defences have proved sufficient to befuddle a jury in the Wellington District Court, leading to the trio's acquittal.

The men, members of the Anzac Ploughshares peace movement, pleaded not guilty to wilful damage and burglary charges. They freely admitted, however, breaking into the base and damaging the dome, which veils technology used to intercept foreign communications.

This is shared by Waihopai's owner and operator, the Government Communications Security Bureau, with the United States, Canada, Britain and Australia as part of the Echelon electronic snooping network.

Among the men's defences was an attempt to characterise the attack as a matter of "necessity" and in the "defence of others". More broadly, these were wrapped into a "greater good" defence, which does not, in fact, exist legally.

It was used in this instance to advance the view that criminal activities are justified if defendants genuinely, even if mistakenly, believe their actions are more advantageous to society than the following of the law, and that those acts will prevent physical harm or another crime.

The trio said they believed that damaging the satellite would stop, even if temporarily, human suffering in Iraq. But they did not, and could not, prove a direct connection between the two or prove their activity had had an impact.

It could just as easily be argued that their action put other lives at risk, perhaps even exposing this country to terrorism. One aim of Waihopai's interception of communications is to pick up the planning of such assaults.

The judge took the view that damaging the spy base could not be defended as preventing harm. The defence, therefore, also canvassed "claim of right", which, at least, is enshrined in statute law.

This asserted that they genuinely, if mistakenly or out of ignorance, believed their actions were lawful. The defence is often used for people who have unwittingly bought stolen goods.

But, in this case, it is extremely flimsy. First, it transgresses the precept that ignorance of the law is no excuse.

Secondly, while it may be possible to think that saving people trumped the cutting of plastic, it defies belief that the men could genuinely have thought the act of cutting through the base fence was lawful. The trial judge had obvious doubts, reserving a question of law relating to the offence of claim of right. This could permit a Crown appeal.

The jury, however, had no such reservations. After an eight-day trial, it took just two hours to acquit the men.

Somehow, it bought the idea that the defendants had believed they had a legal defence. The decision would be unlikely to withstand judicial scrutiny.

In this case, however, obfuscation, allied to a vague sense of unease about the satellite bases at Waihopai and at Tangimoana near Palmerston North, proved the basis for triumph in a jury setting.

The acquittal will not set a legal precedent. That is the domain of judges, not juries. But it will probably encourage others who have attacked public property to mount the same defence.

The widespread disbelief that has greeted this decision means any such attempt will surely fall on stony ground. Clearly, that should have been the case this time, as well.

The Waihopai Three would have gained more kudos if they had pleaded guilty and still achieved their aim of publicising Waihopai's global threat, rather than indulging in jury-flummoxing verbal contortions.