Position Paper on Cannabis
Steve, I'll take a bit of an issue with "Testing for impairment is difficult"
It really isn't that hard. And its a stepped approach. And an approach where you preferably get the person to admit they have a problem rather than you invasively testing for what might not be a problem - drugs in a system does not = impairment.
Firstly we are basically creatures of habit. What we do today we'll do tomorrow. So the first thing managers need to look for is a break in that pattern. Lateness for work, slowness of output, lower quality. Down to things like hand eye coordination, balance, movement etc. These give an opportunity to start a chat.
At the chat you can observe pupil size. (Dilated pupil may be indicative of cannabis related impairment) And are eye movements smooth and focussed. Do they move uncontrolled. The eyes are truly the window to the (impaired) soul.
If you want to dig a little deeper you can ask them to focus on an object in front of their face and you move the object around and see what the eyes do. Or you just move your own body around a bit and see how the persons eyes react.
This can be done by anyone - the purpose is just to form an initial view on which to base the next step.
If you are cheeky you could ask them to stand on two legs, ask them to tilt their head back close their eyes and once they reckon 30 seconds has passed bring their head forward and stay "stop". If they wobble or can't follow the instructions you have a clue.
I would much sooner we had a "just cause" for taking action against someone. There should be a reason why we interfere with a person. Drug testing should be last resort.
Rather than drug testing I would much sooner we focussed on formal Impairment Training that covered things like constriction and dilation of pupils, eye convergence and the Romberg Balance test. For those into compliance, or risk adverse in terms of unions, PG etc then a "certification" course would be handy. I'd sign up for that.