Virender Singh's time in the limelight raises the question – just what should we be allowed to do to "defend" ourselves?

The decision by two Justices of the Peace to throw out charges against South Auckland liquor store owner Virender Singh has been widely applauded. In fact, it is the police who now are in the gun, with Mr Singh demanding an apology from them and the Justice Minister issuing a "please explain" notice regarding their decision to press charges in the first place.

On the face of things, it does look a bit daft. A store owner is confronted by a group of youths, at least one of whom is armed, whom he thinks are seeking to rob him. He grabs a hockey stick and fights them off, getting stabbed in the process. The police turn up after the event (he says it was 15 minutes later), only to arrest and charge him for his actions. Has the world gone mad?

Well, maybe it has – that would explain the popularity of New Zealand's Next Top Model. But Mr Singh's story isn't quite as straight forward as the above precis makes out. He actually wasn't charged for "just defending himself" from robbers. The police alleged, on the basis of witness testimony, that he used his hockey stick to hit one youth in the face, breaking several of his teeth, while that youth lay on the ground with another man sitting on top of him. He also was charged with striking another youth on the back and legs as he tried to aid the first injured man. And it appears neither of these alleged victims were part of the robbery attempt (or, at least, there was not enough evidence they were involved to charge them with robbery).

Simply put, the Police's case was that Mr Singh carried out a punishment beating on two people he mistakenly thought were trying to rob him, after the robbery attempt had been foiled and as the actual perpetrator tried to flee. Mr Singh's own statement to the Police lent this story some credibility; "My actions were not to kill them, only to teach them a lesson not to do it again."

As it happens, the JPs at Mr Singh's depositions hearing decided that the evidence before them was so conflicting and contradictory that it would be impossible for a court to determine what actually happened. Not really that surprising, given the confusion of the scene (which was a wild melee involving multiple protagonists) and the state of some of the witnesses (one of whom, when asked how "wasted" he was on a scale of 1-10, answered he was at "20"). So they stopped the charges going to full trial.

This means the question of "self defence" did not enter into their decision at all. The JPs instead determined there simply wasn't sufficient evidence as to whether Mr Singh really did hit the youths in the way the Police had alleged. If there had been better evidence of this (CCTV footage, for instance), then you can bet the matter would have gone before a jury. And if the evidence was there that Mr Singh acted as the Police alleged, I think there's a better than even chance he'd have been found guilty.

That's because the claim of "self defence" in law doesn't give you carte blanche to whale on people you think are trying to rob you, or otherwise do you physical harm. It's a legal privilege to use "reasonable force" to defend yourself (or others) from an immediate physical threat that you cannot otherwise reasonably avoid. Once that threat ends, then your right to use force ends too. That means if a suspected robber is pinned to the ground, you can't whack them in the head with your hockey stick.

I suspect some people would like to see "self defence" mean more than this. There's something of a move to turn it from an immediate, proportionate "prevent harm" response to an attack, to justifying the use of "preemptive", or even "retributive", force against a perceived threat. So rather than waiting to see if the teenage tagger you are chasing down the street has a knife, you should be able to take a knife with you to use against him. Rather than allow thieves to get away with your goods, you should be able to use lethal force against them.

There's some evidence that the National Government might be sympathetic to such calls. Justice Minister Simon Power, recognising the "considerable public anxiety" over the issue, has asked his officials for a review of how current self-defence laws are applied. Of course, this review may go nowhere. But given the current climate of public angst over crime, it also may be the first step in widening the existing legal privilege to visit harm on those we think are trying to harm us.

Personally, I have some qualms about any such move. For one thing, it plays into a worrying trend in New Zealand towards replacing the criminal justice system with legally-sanctioned forms of vigilantism. I happen to think that the introduction of a regularised, centralised police-and-courts model of justice is one of the better consequences of the British colonisation of New Zealand. It worries me to see our society returning to a bastardised form of utu, shorn of all the deep-seated communal understandings that are needed for such practices to work properly.

For another thing, broadening out the right to "self-defence" to encompass pre-emptive or retributive force presents us with a slippery slope. And at the bottom of that slope lie incidents like this. Or this.

As it happens, we'll never know whether Mr Singh's actions really were justified self-defence. It will take another dairy or liquor store owner to chase a would-be robber out the door with weapon in hand, seeking to mete out a bit of on-the-spot corrective therapy, to determine that issue as a matter of law. Unless the would-be robber responds by upping the violence stakes still further. In which case, we'll be reading another headline about the tragic death of a store keeper.