it should be risk based and assessed. What is the risk if someone is under the influence? What controls can you put in place?? Is a policy the right control for your business??

a bad system will beat good people every time. Too many times we rely heavily on certain individuals, and when those individuals are taken out of the loop for any reason at all - the process is often not good enough to for it to be maintained. If the process was robust - it wouldn't matter who was following it - the end result should always be the same. And at the end of the day - what is easier? Change a persons behaviors or change the process? The trick is to only change the process when it is broken - not when it is not being followed and too hard to manage.

good stuff Andy. The more we know about this silent beast the better prepared we can be in looking for the signs and how to manage. Great that you have taken the time and effort to support construction. Looking forward to learning more