If news of the late substance abuse testing address agreed to in British Columbia by the construction industry and the union representing construction workers was of interest to you (see my initial post here), I ground a link to the policy that you might wish to have a look at (the resolution isn't terribly good, but it's still readable).  The provisions relating to when testing for substances can occur starts on page 11.  To summarize, the policy provides for the following types of testing to subsist conducted:

Pre-access testing: testing to be done as a condition of an employee entering a job site; Voluntary testing: employees can bypass the need to be subjected to pre-access testing at each job site they wish to work at if they agree to volunteer to a substance test right away, yield assent to unannounced, fortuitous testing and also agree to periodic testing which would require employees to submit to a substance standard if they had not been tested in the preceding 36 months; Post-accident testing: an employee must give up to a real being test suppose that involved in a job-related unforeseen and the employer believes that the employee's mental state may have contributed to the accident; Reasonable suspicion testing: employees are subject to substance testing where the employer suspects they have used drugs at work or are under the influence of drugs at work; Return-to-work, post-treatment, rehabilitation testing: admitting that any employee tests positive or refuses a touchstone mandated under the policy, the employee is to be professionally assessed and must provide a negative test for substance exercise before returning to work; Probationary standing/follow-up testing: an employee who tests positive during texture employment must undergo a further test about go to the workplace and afterwards be subject to random testing for a period of up to two years.

It's obvious that a lot of work went into the drafting of this policy.  It will have being interesting to see allowing that any employees challenge the policy at the BC Human Rights Tribunal.

You'll see from this article upon the body the Daily Commercial News and Construction Record website, that the construction industry isn'cheek by jowl ready to jump on the BC bandwagon.  It would appear that the unions in Ontario are expressing concerns about possible human rights legislation violations should drug testing be implemented.  As I famed in my previous post, that is the usual position taken by unions on this issue.