Mr. Harper is right: The Canadian government’s attempts to erode individual freedoms in the name of security started well before the deaths of the two soldiers. Last fall, the government shoehorned increased Internet surveillance powers into an anti-bullying bill, which would grant legal immunity to telecommunications companies that voluntarily hand over customer data. The bill would also further lower the standards of evidence for police officers seeking to monitor Internet activities.

More recently, the government introduced legislation that would give blanket anonymity to informants for Canada’s spy agency. This would potentially allow for a dereliction of a basic principle of justice: An accused person would be unable to face his accusers.

Yet the attacks have apparently loosened the tongues of those in government wanting the country to go even further. The government, Justice Minister Peter MacKay recently mused, should consider further powers to monitor and remove offensive websites, lest they lead to a “poisoning of young minds.” Jason Kenney, the minister for multiculturalism, recently suggested that those suspected of terrorist sympathies be subject to “preventative detention” — which the criminal code already permits — for longer time periods, and a lower legal threshold for the government to detain them.

It’s worth considering that such measures would not have prevented the recent attacks. Michael Zehaf-Bibeau, the perpetrator of the Ottawa shooting, had little online presence. His arrest record, a grab bag of drunken driving, drug possession, assault and weapons charges, suggests teenage overindulgence and inner demons, not a budding terrorist. Having drifted from his family, he lived on the margins of society for years. He’d recently told an acquaintance that the devil was following him around.

In the case of Martin Couture-Rouleau, who hit the two soldiers with his car, law enforcement had already revoked his passport, and he’d been under surveillance for months — including at the mosque he attended. He simply hadn’t done anything to warrant arrest, preventive or otherwise. His online presence, meanwhile, was largely an Islamic-themed cacophony of anti-Semitism and cut-and-paste screeds against Christianity. While disturbing, only in the most totalitarian of states would this sort of thing constitute a crime.