A GROUP of volunteers spent much of 2013 getting 'stoned' on cannabis and jumping into a driving simulator as part of a groundbreaking United States Federal Government study.
USA Today's July 27 report on the study comes days after Lismore Magistrate David Heilpern raised concerns for the second time in several months about the lack of science showing how the drug affects driving.
On July 21, during the sentencing of Jackson Hart, Mr Heilpern said he could not take into account an increased risk to other drivers as the tests identified a detectable, and not a quantifiable level of drugs, such as in drink driving matters.
"The fact is that the tests that are done is not to detect an amount of cannabis in your system that will affect your driving," Mr Heilpern said.
"This is a test about having cannabis in your system."
While on May 20, during the sentencing of David Lloyd Gallagher, Mr Heilpern said research he conducted on previous cases revealed police testing methods could identify marijuana cannabis in a person's system for up to two weeks after consumption.
Mr Gallagher claimed it had been two days since he smoked cannabis when he was pulled over by police.
"There is no evidence that having smoked (marijuana) either days or weeks prior, that your driving is adversely affected," Mr Heilpern said.
"This is not to do with how this drug affects your driving; it is to do with an assessment that you have consumed this drug."
USA Today reported that the comprehensive study involved 19 volunteers consuming specific combinations of cannabis, alcohol or a placebo before using the university's National Advanced Driving Simulator.
The federally funded device closely mimics real driving - including everything from parking lots to dark gravel roads and unexpected situations, such as crashes, near misses or road hazards.
Volunteers used a vaporiser, due to the university's smoke-free campus, to consume federally-grown cannabis and provided saliva and blood tests during their drives to check drug levels.
Additional reporting by Rodney Stevens