A major union plans legal challenges against mining contractors who use urine samples for drug and alcohol tests after a court upheld a decision to allow only the saliva method.
The Australian Manufacturing Workers Union said it would rely on a recent Fair Work Commission decision that upheld an order for NSW-based Endeavour Energy to use only saliva swabs.
The commission deemed urine tests "unjust and unreasonable".
Mining companies prefer urine testing because studies show this method can detect substances such as heroin, cocaine and cannabis used in the preceding few months.
Saliva swab tests reveal cannabis used up to 12 hours previously and harder drugs used up to only three days earlier.
Mining workers caught with drugs in their system face cautions or dismissal.
AMWU secretary Steve McCartney said urine testing was too intrusive.
He said 90 per cent were conducted with an observer in the room.
Mr McCartney said that if saliva swabs were good enough to be used by police on motorists, they were also appropriate for the resources sector.
The union planned court challenges against those employers who used urine testing.
"We will be taking them all on because we owe it to our membership," he said.
"You can tell Rio Tinto, Woodside and BHP (Billiton) that they can be expecting to hear from us."
The Association of Mines and Metals conceded that mining contractors might be challenged in court over the matter after the commission's decision on Friday.
AMMA executive director of policy, Scott Barklamb, feared a general move to saliva testing would undermine safety.
Mr Barklamb said the Fair Work Commission should not have the right to take decisions about drug testing away from management.
"AMMA strongly believes that the only suitable people to be making decisions about which drug and alcohol testing method is best suited to maintaining a safe workplace are the people directly involved in running those workplaces," he said.
"It is not the expertise or role of an employment tribunal, or an employer association, or a union boss to make critically important operational decisions regarding the safety of someone else's employees."