It was under a Liberal government that Omar Khadr's constitutional rights were summarily violated, but it was under a Conservative one that he was transformed into the one-man wedge issue that would ultimately sour Canadians on Stephen Harper's sinister way of doing politics.

Have the Conservatives learned nothing? Relics of the Harper era persist in portraying Mr. Khadr as a "convicted terrorist" who "confessed" to egregious crimes that took the life of one U.S. solider in Afghanistan and permanently maimed another. They seek to stir up outrage at the Trudeau government's decision to settle Mr. Khadr's $20-million lawsuit against Ottawa for half that amount on the grounds that any wrongs committed against him have since been righted by Canadian courts.

"The fact that he is living in Canada at liberty should be compensation enough," according to Conservative foreign affairs critic Peter Kent. "After all, he is a former enemy combatant."

Story continues below advertisement

Stop it. Anyone with a whit of common sense, much less compassion, knows that the Canadian-born Mr. Khadr, captured at 15 in a raid on an al-Qaeda compound in Afghanistan, should never have been labelled as such. And that it was only in the fog of war that followed the 2001 terrorist attacks on U.S. soil that such labelling was ever allowed to happen in the first place.

Then Liberal foreign affairs minister Bill Graham's first instinct was to resist such a rush to judgment. On Mr. Khadr's capture, his department issued a statement deeming it "an unfortunate reality that juveniles are too often the victims in military actions and that many groups and countries actively recruit and use them in armed conflicts and in terrorist activities … Canada is working hard to eliminate these practices, but child soldiers still exist, in Afghanistan" and elsewhere.

News of Mr. Khadr's capture, however, emerged within a few days of the first anniversary of the attacks on the World Trade Center and the Pentagon. The public mood was not one of forgiveness, but one of resolve in seeking justice for 9/11 victims, and for the Canadian and American soldiers who had died in the subsequent war in Afghanistan. Mr. Khadr also happened to have been the son of a real Canada-hating al-Qaeda combatant, who had taken him as a child to Afghanistan. Then prime minister Jean Chrétien's government soon caved in to public opinion and U.S. pressure, enabling Mr. Khadr's interrogation at Guantanamo Bay in utter defiance of his constitutional rights.

Still, it was Mr. Harper, leader of the Canadian Alliance at the time of Mr. Khadr's capture, who picked up this soiled ball and ran with it. From 2002 and throughout his almost 10-year stint as prime minister, he milked the Khadr case for all its political worth, seeking to make an example of this youngster of notorious lineage and provide proof of his own tough-on-terrorism credentials.

The problem was, Mr. Khadr kept ruining the Conservative narrative by proving, time and again, that he was "better than the person [Mr. Harper] thinks I am." In 2008, Mr. Harper's own government's officials deemed Mr. Khadr "salvageable, non-radicalized and a good kid." Yet, even as evidence mounted that the treatment of prisoners at Gitmo and other tough-on-terror tactics actually did far more to encourage the radicalization of young Muslims than deter it, Mr. Harper and his ministers never let up in their demonization of Mr. Khadr. They even suggested Mr. Khadr could be stripped of his Canadian citizenship under Harper-era legislation that the Trudeau government recently repealed. Right up until its defeat in 2015, the Harper government sought to overturn the easing of Mr. Khadr's bail conditions while he awaits the outcome of his appeal of his conviction before the U.S. Court of Military Commission Review, even though the entire planet knows that conviction was bogus and could only have been arrived at under the Wonderland-like legal distortions of the U.S. military commissions set up to try Mr. Khadr and other Gitmo detainees.

If the panicky aftermath of 9/11 helps explain the context for the trampling of Mr. Khadr's rights, there is no explanation for the Harper government's relentless exploitation of the Khadr case for political gain. By 2015, the diminishing returns of that political strategy were evident. Canadians had grown weary of Mr. Harper's Manichean world view.

If the Conservatives ever want to again be worthy of government, they should congratulate Mr. Trudeau for closing the Khadr chapter on the cheap, let Mr. Khadr get on with his life and wish him luck.