Without supporting QF's stance, I'd imagine that any employer could be held lible should an employee cause damage/injury/death whilst under the influence of any drugs, prescription or not. The latest buzz phrase,
Duty of Care springs to mind.
As an aside, in a past life, delivering steel work to and from a hot dip galvanising plant in Northcote, it was common practice for many plant operators to drink all or part of a bottle of vino, over a joint or two, at lunch.
Stoned & p!ssed people falling into vats of molten zinc do not fare very well.
Not to think of the dangers of such people then operating machinery!
