It is deeply wrong for any government to prohibit a previously legal and legitimate practice out of nothing more than unfounded fear. That is what the Liberals would be doing if they banned handguns.

In the wake of a spate of shootings in Toronto – 14 during the August long weekend and another five last weekend – Mayor John Tory is calling for such a ban. On its face, he has good reason. According to Statistics Canada, more than two-thirds of all firearm-related crimes in urban areas involve handguns.

In response, Mr. Trudeau promised Tuesday that, if the Liberals are re-elected, “we will be able to introduce further measures to strengthen measures against guns.” He refused to reveal what specific measures he had in mind. But the Liberals are under considerable pressure to repeat Paul Martin’s pledge to ban civilian possession of handguns, which was part of his unsuccessful 2006 election campaign. Polls show that more than half of Canadians support such a ban.

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We have been arguing over the best way to deter gun violence since at least the École Polytechnique shooting in 1989. Part of that debate centres on handguns, which are integral to the gang-related violence that now accounts for one-quarter of all homicides in Canada.

Police tell us that most handguns used in crimes are smuggled into Canada illegally from the United States – an unavoidable consequence of policies that place a high importance on moving people and products easily between the two countries.

But some crimes may have been committed with handguns that were legally acquired in Canada. They may have been stolen from their rightful owners, or someone might buy a gun and then sell it on the black market for a profit. Or a person might acquire a handgun legally and later use it against a spouse or partner, although acts of domestic violence account for less than 10 per cent of gun-related crimes.

How often is a handgun that was legally acquired in Canada used in a crime? We have no idea. Despite decades of debate, no one has produced a properly researched report.

“We don’t know the origin of firearms involved in gun crime in Canada,” Lynn Barr-Telford, director-general in charge of justice surveys at Statistics Canada, acknowledged last year at a summit on guns and gangs organized by Public Safety Canada.

This is an outrageous act of neglect. Yes, there are challenges in gathering data. Different police departments collect information differently, and tracing the origin of a handgun can be difficult. But a determined government could come up with a reliable estimate if it wanted to. No government has tried. It’s almost as though we would rather argue from prejudice and passion than from facts.

If credible research demonstrated that a significant number of handguns sold in Canada are falling into the hands of gang members and other criminals, then that would be grounds for further restrictions or an outright ban. But without that evidence, depriving handgun owners of their weapons – which they may use for target practice, or because they are collectors – is capricious and unfair.

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Ottawa and participating provinces might ask the federal and provincial auditors-general to take on the task. Since handguns are mostly owned by urban dwellers, and since handguns may be used for different reasons in different environments, the auditors might look at handgun-related crimes in selected cities. Three years should be sufficient for a final report.

There are other ways to fight gang violence. One is to tackle systemic urban poverty. But such an approach is very expensive and has produced mixed results over the years.

The federal Conservatives want tougher sentences for gun- and gang-related crime, though there is plenty of evidence that such an approach simply increases the prison population, without lowering crime rates.

Giving the police additional powers can help to reduce gang violence. It can also lead to charges of racial discrimination and abuse.

Fighting poverty, toughening penalties, bolstering police powers are all deeply controversial. But banning handguns: That would be quick and easy and popular.

Except that imposing such a ban without evidence that legally acquired handguns pose a risk simply panders to prejudice and fear. And no one should want to be part of that crowd.

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