There is nothing that quite tests our feelings on capital punishment as exceptional cases.

Paul Bernardo and Karla Homolka, who committed horrible murders in Niagara

Anders Breivik, who killed 77 people in attacks in Oslo and a camp for political youth in Utøya, Norway.

And, now, Luka Rocco Magnotta.

These cases are exceptional. They are so horrific that they almost demand brutal punishment.

They’re also exceptional in the context of evidence. In each of these examples there is significant proof that they are guilty – videos or confessions or both.

In January 2011, Prime Minister Stephen Harper said “I, personally, think there are times where capital punishment is appropriate” and perhaps he was referring to such extreme cases. It’s easy to understand the sentiment, one which is being expressed frequently in popular discussions or on social media since the beginning of the Magnotta affair.

But it is perhaps these instances that best test our commitment to beliefs.

I don’t support capital punishment. I agree with Socrates that it can never be just to harm another. Yes, lock them up and throw away the key … but it is wrong to kill prisoners.

Furthermore, the risk of false convictions is significant. The Steven Truscott case was brutal enough to justify a significant response, but in retrospect we have learned that he was innocent. Supporters of Capital Punishment in the US have for years claimed that in the modern era no innocent people have been executed – a claim that has recently been proven false. Texas executed innocent Carlos DeLuna in 1989. And given the evidence of false convictions in the criminal justice system as a whole, with more than 2000 people exonerated after convictions by DNA since the late 80s, it’s highly possible this is not the only time.

To those who balk at the cost of locking up a Bernardo or Magnotta, I’ll point out that the process of repeat appeals and highly subsidized legal defense in countries with Capital Punishment like the US (the complicated process with many checks being necessary to justify such a system) makes cases with the death penalty extremely expensive.

That aside, the biggest issue is the morality of a state killing its citizens regardless of the reason. While I agree that these exceptional cases provoke an emotion response for a brutal punishment, that their lives should be taken for the harm they committed, I think we need to resist that.

I predict that as Magnotta is returned to Canada and his trial begins, we will see more calls to return to Capital Punishment in Canada, at least partly from conservatives. We need to resist those calls. We need to say that Capital Punishment is excessive and expensive, that locking someone up for their entire lives, never ever to be released, is sometimes justified … but killing them is not. We need to point out that people like Magnotta or Bernardo aren’t discouraged by the so-called deterence some have claimed Capital Punishment has – if Capital Punishment were a deterence, the US which has the highest per capita executions would have the lowest crime rates in the developed world, not the highest.

A motion passed by Parliament in 2008, with partial conservative support, said that the government should “stand consistently against the death penalty, as a matter of principle, both in Canada and around the world.”

We shouldn’t let someone like Luka Magnotta change that principle.