The debate about arming the police is one of those insoluble arguments in which cause and effect endlessly chase each other's tails, each occasionally claiming to have caught the other.

Regrettably, the public discussion usually flares in the wake of the shooting of an officer, when a mixture of grief, shock and outrage militates against sensible analysis.

But at any time the argument is fraught: those who oppose the "general" - that is to say, gun-on-hip - arming of frontline police can be glibly characterised as being preoccupied with the civil liberties of criminals, when cops' lives are on the line; those who support a fight-fire-with-fire response to an armed criminal fraternity seem untroubled by the lack of good research evidence that it has ever worked anywhere.

Mercifully, the issue's return to the headlines this week was not because another police officer had been shot. Addressing the Police Association's conference in Wellington on Wednesday, Police Minister Judith Collins foreshadowed the possibility that, within a few months, every one of the force's 2700 police cars could be fitted with a lock box containing two pistols and two rifles. These boxes would be inside the vehicle, not in the boot.

Police Commissioner Howard Broad is currently conducting a review of the matter and his conclusions, due on the minister's desk by the end of the year, are expected to include the lock-box proposal; Collins this week made it plain that she would be inclined to support it.

It would not be a major leap: figures released in April showed that almost one car in four has a gun safe in the boot, although they do not always carry firearms. But the idea of general arming is of an entirely different order and it is far from clear that the public supports it.

A Herald poll in January showed readers were opposed, by a margin of almost two to one, to general arming and were happy with the current practice of using specialist squads to deal with incidents involving firearms.

The Police Association, whose president, Greg O'Connor, has described this view as "nostalgic and unrealistic", has its own research showing almost the opposite - 58 per cent of the public support general arming and 72 per cent of association members do - up from 47 per cent two years ago and barely 25 per cent in 2006.

The discrepancy, doubtless partly attributable to the wording of questions, shows how volatile the issue is. But plainly officers' attitudes are hardening. The question is whether that should decide the matter.

Tellingly, the two officers shot in that sample period, Senior Constable Len Snee and Sergeant Don Wilkinson, had elected not to arm themselves before the shootings that killed them, both of which took place in the course of drugs inquiries.

There is a case to be made that the problem the police face is not a lack of readily available firepower but a faulty set of procedures when dealing with suspected drug dealers, who are axiomatically becoming more heavily armed with every passing day.

To arm all police as a matter of course does not sit well with the vast majority of New Zealanders. We react with shock to gun-toting cops across the Tasman and in the Americas and we don't want the same here. Our police do a great job and deserve protection, but once they embark on an arms race with the country's criminals, there will be no going back.