Imagine you're standing in a crowded public place — a playground, a movie theatre, a grocery store — when all of a sudden, you feel someone press something into your ribs. A man in a mask is now standing inches from your face, holding one gun against your body and pressing another into your hand. "Kill them," he whispers into your ear. "Kill them, or I'll kill you."

When a court deems an offender "not criminally responsible" (NCR), it accepts that a crime was committed under these sorts of conditions. There is no actual man in a mask, of course (if there was, there might be grounds for a duress defence — a separate issue); rather "the man in a mask" is a euphemism for a mental illness that has you convinced you must hurt others, usually to stay alive.    

On March 5, 2009, a Manitoba court found Vince Li not criminally responsible for the horrific death of Tim McLean on a Greyhound bus seven months earlier. Li, who has since changed his name to Will Baker, said he heard the voice of God telling him to decapitate and cannibalize McLean, a fellow passenger who Li believed was an alien.

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Li's absolute discharge is unconscionable to many who were affected by Li's gruesome crime including the family of McLean, above, the Greyhound passenger beheaded by Li in July 2008. (Canadian Press)

Li's schizophrenia was undiagnosed at the time of the killing. After he was deemed NCR, he was sent to the Selkirk Mental Health Centre for treatment. And last week, after years of earning back small freedoms such as supervised day trips and unescorted outings, Li was granted an absolute discharge.

The decision was blasted by critics nationwide, as Canadians asked how a man who decapitated a Greyhound passenger less than 10 years earlier could possibly be set free. Social media lit up with calls to send Li to prison, and interim Conservative leader Rona Ambrose moved to score a few political points by tweeting "Justin Trudeau must put the rights of victims ahead of criminals."

Ambrose is smart enough to know that Li is not actually a criminal but a little too politically minded, apparently, to care. She's not entirely alone. Many of us like to think of ourselves as progressive thinkers on mental health, proudly tweeting #BellLetsTalk to try to erase the stigma around mental illness. And indeed, it's easy when the scenarios are rather straightforward: don't fire someone because he or she suffers from depression; be patient with friends and family members who experience anxiety. But what about when someone commits a heinous, violent act while in the midst of a paranoid delusion? Er… um… what Rona said.

There is a reason why offenders deemed not criminally responsible are sent for treatment, not imprisonment, and why they are eventually released: if we accept that an illness compelled someone to commit a crime — the man in the mask, pressing a gun into his ribs — it is unjust to keep that person confined when that illness is under control. In Li's case, according to the Manitoba Criminal Code Review Board, on the advice of Li's psychiatrist and other mental health specialists, his man in the mask is gone — for now.

Absolute vs. conditional discharge

Where critics of the case have a point is in the decision to grant Li an absolute discharge, meaning he is essentially free of the justice system, rather than a conditional discharge, whereby Li would be required to stick to a treatment plan or report regularly to a psychiatrist. The absolute discharge does make sense from a legal perspective: the review board is required to choose the "disposition that is the least onerous and least restrictive to the accused." As long as the individual "does not pose a significant threat to the safety of the public," he or she must be discharged absolutely.

Li does not pose a risk to the public now that he is on his medication, according to the medical professionals who have treated him for the last near-decade. But the checks and balances that once existed for him (from a legal perspective, at least) disappeared the moment he was granted an absolute discharge. There is now no legal recourse if he stops taking his medication or seeing his psychiatrist, which is unconscionable for many of those affected by Li's actions, including McLean's family. Understandably so.

Some mental health advocates (and perhaps, their libertarian friends) would call it unjust to subject NCR offenders who have completed treatment and rehabilitation to any conditions. And they're right: it isn't fair, but few things about mental illness are.

To many, it won't seem "right" that someone has to check in with the legal system forever just because he or she suffers from an illness and committed a crime, but at the same time, it's arguably worse to assume that everything is fine, to shrug off whatever act landed the individual in the justice system in the first place, and to blindly trust that he or she won't decide one day that medication is no longer needed. This isn't a call to have every person who suffers from mental illness monitored forever by law enforcement; but after someone has committed such a violent, traumatic act, he or she shouldn't ever be completely "free."

Li was undiagnosed before he killed McLean, meaning he has never had to voluntarily stick to a treatment plan. We have to acknowledge he is sick, not evil, which means he can't be locked up forever. At the same time, he is being treated, not cured, which means there is always the potential of his masked man coming back. Li listened to what he had to say before; the system should make it harder for that to happen again.

This column is part of CBC's Opinion section. For more information about this section, please read this editor's blog and our FAQ.