The Construction, Forestry, Mining and Energy Union (CFMEU) had taken up the case of truck driver Tara Cunningham, who was found to have more than four times the cut-off figure for methylamphetamine in a random site drug test on April 2 last year.

Fair Work Australia announced this month it had found in favour of contractor Downer EDI Mining after hearings late last year.

Fair Work Australia Commissioner Ian Cambridge was scathing of the CFMEU for their representation of Ms Cunningham.

“It was highly regrettable to observe during the hearing that an organisation which apparently conducts campaigns which strongly advocate safety in the workplace could contemplate a proposition which, in effect, would countenance a person driving a 580 tonne truck whilst having methylamphetamine in their body at a level four times the reportable cut-off figure,” he said.

Ms Cunningham had argued she believed she had been the victim of a drink spiking incident while drinking at a hotel.

She also said there had been a number of cases on the mine site where employees had not been dismissed after failing a drug test.

But Mr Cambridge found Ms Cunningham had been dismissed for “serious misconduct involving a breach of the employer’s drug and alcohol regime”.

“The nature of the established breach of the drug and alcohol regime has been described as a breach of a cardinal rule,” he said.

He said the test results at more than four times the cut-off level would “of itself, provide valid reason for the employer to terminate the employment of the applicant”.

“This test result was appropriately treated as a prima facie serious risk to the safety of fellow workers,” he said in the report.

The decision was welcomed by the Australian Mines and Metals Association who have supported the eradication of safety risks posed by drug use.

Association chief executive Steve Knott said he hoped future decisions adopted a “similarly unsympathetic” view of drugs in the workplace.

“For decades, many remote resource projects have regularly tested for drug detection,” he said.

“It is well understood by employees that this acts as both a deterrent and as an absolute safety measure.

“Unfortunately, this zero tolerance approach is often undermined by the undue interference of third parties which believe they ‘know better’ or argue on points of ‘fitness for work’, ‘recreational use’, or ‘level of impairment’.

“Remote mine sites, large construction projects and FIFO [fly in, fly out] villages are not places where you would want to work alongside a colleague under the influence of drugs. Employers must have the right to manage such safety risks and say ‘if you touch illicit drugs, there is no place for you on our sites’.”