Drug testing for workplaces is one of the modern growth industries.
Spurred by health and safety legislation, and sometimes productivity concerns, more employers are preparing policies, implementing tests and acting on them.
Among those reviewing and consolidating policies is the Dunedin City Council.
Staff are being asked to consider a proposed new alcohol-and-other-drug policy, which details procedures for random and targeted testing for illicit substances.
As council community life general manager Graeme Hall said, the council had an obligation to provide a safe workplace.
The laws around drug testing generally allow for pre-employment screening, they can be instituted for "reasonable cause" and random testing is possible in safety-sensitive areas.
The "reasonable cause" provision has been around for many years and, as listed by Mr Hall, this could be invoked after outbreaks of violence in the workplace, excessive lateness, changes in personality or appearance, bloodshot eyes or intense anxiety or panic attacks. No doubt, there are areas for dispute here but the principle is established, as has the standard that drug tests can be taken after accidents or "near misses".
More problematic is random testing because of doubts about what are the safety-critical areas and because the intrusion on privacy is so substantial.
When the conflicting demands of safety verses privacy and "bodily integrity" are balanced, nevertheless, safety is the obvious winner.
That includes the safety of the particular employee concerned, of other staff and of the public.
It was in 2004 that the Employment Court backed Air New Zealand's random drug testing of those in "safety-sensitive positions", concluding these were where employees exposed themselves or others to risk of injury. That included pilots, maintenance workers and managers making safety decisions.
It did not include payroll staff and many desk jobs. Four years later jockey Lisa Cropp challenged racing industry random testing all the way to the Supreme Court.
The court went so far as to say that random drug tests were actually necessary so that jockeys were deterred from taking drugs.
Race-day safety would thereby not be compromised.
Riding horses is dangerous and airline pilots have many lives in their hands.
But what constitutes safety-sensitive positions becomes hard to define down the scale. These days is it likely that random tests are permissible for bus drivers.
Will we reach the stage where everyone who drives a work vehicle can be tested? They put both themselves and others at risk. Maybe that will happen as society becomes increasingly safety conscious.
What about pre-school teachers caring for substantial numbers of vulnerable small children? Where should the lines be drawn on those operating machinery of various types?
The city council, for its part, has included Moana Pool lifeguards and those using heavy machinery in its proposed policy.
That is appropriate. How many others should be included?
The law seems at this stage to leave the final decisions on safety sensitivity up to employers, although too broad a definition could well be challenged legally.
The council is consulting staff, as it must by law, and details and protocols will be important.
Work impairment is what counts and a little alcohol or a trace of cannabis - traces of which can sometimes be detected weeks after consumption has stopped - should usually not be cause for action, as Mr Hall has said.
Staff unions, however, and not surprisingly, have reacted with concern about specific provisions for searches of private property and the use of covert electronic surveillance on work premises.
Despite the growing use of random drug testing, some employers will be reluctant to charge ahead.
In some circumstances it can undermine the trust between staff and managers, it can take much time, cost and effort to introduce a testing regime.
And the testing itself is expensive.
Nonetheless, sometimes random drug testing could actually act as a spur for individuals to improve their lifestyle and their health and it might well also increase productivity.
While these are insufficient reason for random testing, crucially, accident rates can fall. Sensibly, random testing is becoming a fact of life in "safety-sensitive" areas and in danger industries like forestry.
