The state government is planning a massive roll-out of the same drug-driving tests that misdiagnosed Mr Hunt, with 100,000 NSW drivers expected to be tested - and it's not to identify those under the influence of drugs (a different offence) but simply whether they have the "presence" of drugs in their systems. Police admit there is no lower limit used for the amount of drugs detected. "The first moment I realised something was wrong was when the policeman came back to me and said 'I think we are going to have a problem here'," Mr Hunt said. The test had detected methamphetamine in his saliva. He was arrested and taken to a portable testing station, where a second test was negative. A further sample was sent to NSW Health pathology. Two weeks later he got the result: positive. "I had been sitting there going to my wife 'no, no, no, this won't come back positive'," he said. "I have never taken drugs in my life."

Mr Hunt's lawyers demanded the sample be retested. The same NSW Health lab, testing the same sample, got a negative result. A further test was also negative, and in court police did not present evidence, and the case was dismissed. "I have no trust whatsoever in the police any more," Mr Hunt said. "If it can go wrong once, it can go wrong again, and I don't want to lose another five grand." Fairfax Media has also spoken to a woman, who did not want to be named, who had marijuana detected despite never having used the drug. She also had a positive, then negative, then positive result, but was never told she could get it retested. I have no trust whatsoever in the police any more. Steve Hunt Greens MP and justice spokesman David Shoebridge said the roadside drug testing was a "lottery".

"The problem is the police are testing for tiny trace elements of drugs and this makes the results inherently unreliable," Mr Shoebridge said. "Steve was just minding his own business … and he had his life turned upside down by a plainly stupid law. It's awful what has happened to him, how much it has cost, and we know he is not alone." Mr Shoebridge said it was extremely difficult to get legal costs back from the government, but he had written to the Police Minister to suggest Mr Hunt be given an ex-gratia payment. "It's time to scrap the failed roadside testing regime and put in place a rational program that tests for impairment, and tests for every drug, not just a handful of illegal drugs," Mr Shoebridge said. NSW Police maintain the tests are an important deterrence tool in preventing road accidents caused by impaired drivers, which are implicated in 14 per cent of road fatalities. One in 10 tests this year returned a positive result, compared with one in 300 alcohol tests. Sharon Neville, the acting director of the NSW Health Forensic and Analytical Science Service (FASS), said that since roadside drug testing was introduced in 2007 it had tested more than 14,000 samples, and Mr Hunt's case was the only error it was aware of.

"The initial incorrect result reported by FASS was due to a manual handling error," she said. "Additional measures and quality control steps were implemented as a result of this case, with all samples now being analysed twice before reporting. These steps ensure tighter controls on manual handling and all other parts of the process." She said the screening tests conducted by NSW Police had different sensitivities to the "comprehensive" testing equipment used by FASS.