Nearly 100,000 NSW residents each year will be subjected to roadside drug testing that police admit does not look for drugs that are still active in a person's system and critics say is about mass punishment of drug users, not road safety.

Documents obtained by the NSW Greens under freedom of information laws show there is no lower limit of drugs that are detectable in the saliva of people subjected to the roadside oral drug tests, and no proof the tests are effective in preventing crashes.

Safe storage "is essential in Australia's success in reducing firearms deaths, especially suicides": David Shoebridge. Credit:Max Mason-Hubers

The offence of driving "with the presence of cannabis, speed/ice or MDMA/ecstasy in oral fluid" is separate to the charge of driving under the influence of drugs or alcohol, and police operating procedures reveal the tests do not imply a person is impaired by their drug use.

Greens MP David Shoebridge said the testing was a waste of money that undermined the legal system by making it a "de facto criminal offence of having potentially minuscule quantities of drugs present in your system".