Have the proponents of such practices never heard of civil liberties? human rights? the Charter? Or do they just not agree with them?

If employers want to engage in a police state approach to substance abuse (or, in the context discussed here, substance USE, which is a very different thing...), let them start at the top. Subject all of the executives, in-house lawyers, sales staff, and others who shape company policy to the same testing they want to impose on workers, and fire anyone who fails - without any severance package, of course.

Even that wouldn't justify imposing such policies on workers, who have no control such decisions, but at least management could claim to have a vestige of integrity when they talk about sacrificing workers' rights for the greater good.

I'm not holding my breath, though.

Employers owe it to their employees, and members of the public who may come into contact with their employees to maintain a safe workplace. Testing, used in appropriate circumstances, is one tool which can increase the safety of the workforce and the public. The response chosen by an Employer to a positive test can have a greater focus on the best interests of the individual employee. In house counsel should ask themselves what the headline would look like the day after a catastrophic accident. Certainly, they would want to be secure in asserting that the Employer did all it could have.