Peace activists gather at Waihopai Spy Base trial

Fine arguments by the legal farternity - so if one goes and throws a brick through the window of someone (or some organisation) who has done damage to you or your family it would also be OK.
Anarchy will come of arguments like this, if it is not already here!
But before that, the legal farternity will self destruct in this whole madness of not being able to deal with the most obvious swiftly and decisively.
And all of this is a burden for the Tax payer once again.

If you look at the waste from this distruction on a global level, if what they did stopped only one guided missle. it was less wasteful and no one gets killed

The action was certainly not undertaken irrespectively; they decided to do it after a lot of thought, research and previous protesting. They felt that traditional lawful means to express displeasure were not available to them in this situation, not least due to the secrecy of the spy base. The law does allow for force and property damage in extreme situations of necessity, self-defence and defence of another, which is what their defense are arguing. In any case, if the US and its allies (including the assistance of the NZ taxpayer through Waihopai's intelligence-gathering) would restrict themselves to lawful means of expressing themselves, the Iraq war would never have taken place, along with a great deal more of the US's foreign policy.

Idiots who commit willful damage to someone else's property irrespectively need the full impact of the law to fall upon them. You idiots, use lawful means to express your displeasure or otherwise GROW UP and GET A LIFE.

They are there to help pay for the damage.