As the world watched with grim fascination the gruesome details of Lin Jun's killing in Montreal these past two weeks, Public Safety Minister Vic Toews took the time to tell reporters that his proposed Internet surveillance bill, Bill C-30, would have helped police investigate.

Perhaps so. But in reality, the suspect, Luka Rocco Magnotta, was caught relatively quickly, considering that he was already on another continent short days after the events. And in the end Mr. Magnotta's capture wasn't prompted by high-tech surveillance, but by sharp-eyed citizens.

Even the alleged evidence of Mr. Jun's killing wasn't hidden on some personal computer or private site, forcing police to obtain the kind of warrants that Bill C-30 would heavily streamline. It was available on a public website for anyone to see (and, disturbingly, it appears that many, many people wanted to see).

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Is digital monitoring starting to generate diminishing returns?

To be sure, the ability to monitor Internet activity has proved beneficial in countless cases. There have been numerous high-profile busts in child pornography – Mr. Toews's most often-cited cause – because investigators were able to quickly and easily collect evidence and track offenders down.

Surveillance also serves more than one purpose: Besides helping to snare criminals, it helps to deter them. In a corner convenience store, letting people know you've got cameras watching them is just as important as the watching itself.

However, surveillance may be hitting a saturation point. Twenty years ago, it was difficult to leave a significant digital footprint – today, it's pretty difficult not to. More and more people are aware they're being watched online, by someone or other, all the time. As such snooping becomes pervasive, people may stop altering their behaviour in response to it.

Mr. Magnotta not only seemed unconcerned with being observed, he positively sought it out. When caught by German police, he reportedly was sitting in an Internet café looking at photos of himself on the Web. Would increased surveillance have helped to catch the suspect sooner? Maybe. Would it have prevented the crime? Almost certainly not.

Of course, it's impossible to generalize from such an extreme case. But this summer, the decreasing value of surveillance as a deterrent will be the subject of a massive case study – the London Olympics.

Over the past decade, London has made a strong case for itself as the world's surveillance capital, with closed-circuit cameras (CCTV) seemingly on every corner. The Olympic Games, during which the city will be under the world's magnifying glass, has only exacerbated the situation.

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So overt is the theme of surveillance there that the Olympic mascots, two creatures called Wenlock and Mandeville that look like blobs of mercury in unitards, don't even have faces. Instead, each mascot greets onlookers with a giant, face-encompassing eye that "lets Wenlock record everything," according to Games organizers.

If there's any wrongdoing during the Games, London's massive mobilization of monitoring technology may help to catch the perpetrators. But will it achieve the organizers' much greater goal of deterring anyone or anything that might damage the event's image? When surveillance cameras are more common than streetlights and being watched is the norm, it can become just another part of the background, more noise to be ignored.

In 2009, a group of criminologists reviewed more than 40 studies on England's CCTV systems. They found that, despite massive costs, the surveillance had little effect on crime. The only area where CCTV did have significant impact was on thefts in car parks, when the devices were used along with better lighting and more guards.

In the U.S., large-scale surveillance networks have produced mixed results. In some neighbourhoods of Baltimore, for example, crime dropped significantly where cameras were installed. In others, criminals were largely undeterred.

To be sure, many people aren't ready to accept constant monitoring as a fact of modern life. Earlier this year, millions of Internet users in the U.S. and Canada stood their ground against wide-ranging Web surveillance bills such as Mr. Toews's C-30, forcing politicians to backtrack.

But instead of dying, this kind of legislation tends to resurface in modified form a few months or years later, the authors betting that gradually fewer and fewer people will complain.

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Every time Mr. Toews sings the praises of his proposed surveillance law, he will face resistance from critics on very legitimate civil-rights grounds. But there's another question policy-makers need to consider when it comes to spending millions on more digital surveillance: What if a growing number of people have come to terms with being watched all the time, and what if many of them no longer care?

Omar El Akkad is The Globe and Mail's technology reporter.