There is much we can learn from the shambles that became known as the case of the Urewera Four. One very important lesson was that you have to be very careful when handling loaded firearms, because you never know when the police might go off.
The police, to put it mildly, came on strong in October 2007. About 300, including heavily armed, balaclava-wearing members of the Armed Offenders Squad and anti-terror unit, raided sites around the country under cover of darkness. Who did they think they were dealing with? Kim Dotcom?
It's hard to imagine anyone, especially already disaffected Tuhoe, on the receiving end of that treatment becoming less radical as a result. On the contrary, you can be sure several firebrands of the future were born that day.
And four guns were seized.
Unfortunately, there is an element in the police force for whom only one thing is worse than terrorism and that is being made to look foolish. Once officers with this mindset get on to something and decide they are right, they will ignore all evidence to the contrary in an effort to get their man or men. Arthur Alan Thomas can tell you about that.
So the police persisted and landed us with the most expensive court case in our history. The original platoon of defendants was whittled down to four - Tame Iti, Te Rangikaiwhiria Kemara, Urs Signer and Emily Bailey. The phone-book size catalogue of charges dwindled similarly.
The jury could not reach a verdict on the more serious charges, of belonging to an organised criminal group.
Surely one look at the defendants made it obvious that there was always going to be a problem letting them anywhere near the word "organised". They looked in the dock like nothing so much as a panel of judges on a TV talent show. Tame Iti is a great showman and an interesting thinker, but he doesn't have the panache that is essential to be a truly successful criminal mastermind.
The four defendants were variously found guilty of unlawful possession of firearms and unlawful possession of a restricted weapon, Molotov cocktails.
You can find unlawfully possessed firearms on numerous rural properties around the country. And as for a Molotov cocktail, it is a quaint home-made weapon as likely to injure the person wielding it as to harm its target.
As terrorism goes, it was entry-level stuff. The four would have struggled to make it through the front door at al-Qaeda. They'd have been lucky to get "Just leave your CV and we'll let you know if something comes up".
It's lucky for those who were raided - and the police - that no one was killed and martyrs were not made in this affair. There is still a danger that Iti and Co could be made into heroes. They do not deserve to be. They run around playing with guns.
Now we have the awful possibility of a retrial. Costs won't be a factor in a retrial, says Crown prosecutor Ross Burns. Nor should they be. Common sense should, though, and that costs nothing, except perhaps a little wounded police pride. Let's not throw good money after stupid.
So far we have already wasted $6 million that could have been better spent on community policing, which we know actually prevents real crimes.
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The Nick Smith affair is a tragedy. A man of great experience, moral authority, high intelligence and vast political skills probably wouldn't have got himself into this kind of muddle.
Smith, on the other hand, was just an Accident Compensation Corporation waiting to happen.