Australian National University academic David McDonald has questioned the effectiveness of the tests, and says he has been "extremely disappointed" by the lack of public knowledge about drug driving in the ACT.

"I feel the public has the right to know the law and explicit information for people who use drugs and what it means for them to drive safely."

It's a call which has been echoed by civil liberties groups, which have been critical of the zero-tolerance approach to the laws.

The ACT was the last Australian jurisdiction to introduce random roadside drug testing in May 2011.

ACT Policing figures show 116 drivers tested positive from 2429 drug tests in 2013.

In 2012, police conducted 1733 drug tests, of which 37 were positive.

Under previous legislation, police had to suspect a driver was under the influence of drugs before they tested them.

Police use a swab which is placed on the tongue; the test takes about 10 minutes.

It detects cannabis, speed, ice or ecstasy. The tests do not pick up heroin or synthetic drugs.

If the initial saliva swab tests positive, it is sent to a laboratory for further testing.

Any positive result leads to an offence.

Speaking at the Alcohol, Tobacco and Other Drug Association ACT conference this week, Dr McDonald called for a widespread publicity campaign about the tests, similar to those which exist for drink-driving.

"It seems to me there's a need for broad public education, as well as targeted information and that's best done through drug peer groups."

He did not believe such a campaign would condone drug use in the community.

"It's simply acknowledging the truth that people are using drugs and people will continue to use drugs, and if we're smart we'll adjust to that fact."

ACT Council for Civil Liberties vice-president Tim Vines said the zero-tolerance approach to roadside drug tests meant any offence was not based on the driver's level of impairment.

"What is a random drug test then? Is it a test for road safety or is it to test whether you've been using drugs?"

People had a right to know whether they would test positive for drug driving if they passively inhaled marijuana smoke, added hemp seeds to their breakfast cereal or took an ecstasy tablet on the weekend.

"People will support roadside drug testing if it's a public safety measure, but people won't support broad power to police to randomly drug test people."

Professor Max Cameron, from Monash University, has carried out early research into the effectiveness of random drug testing and said it had the potential to deter the general public in a similar way as random breath testing had been shown to reduce drink-driving.

He said drug testing was expensive - an average of $143 per test - and took more time for police officers than random breath testing.

However, he believed the investment was worthwhile.

"I'm confident that in the end, especially if the testing can be made cheaper, that we can deter drug driving in much the same way."

Mr Cameron said the fact the testing only detected three types of drugs had been driven by the technology that was available. He thought it was only a matter of time before the tests were expanded to detect a wider range of illegal drugs.

Police Minister Simon Corbell said ACT Policing and the Justice and Community Safety directorate were developing a public awareness campaign which would be rolled out in the 2015-16 financial year.

The campaign would focus on raising awareness of the dangers of drug driving and the legal consequences of being caught.

Mr Corbell said random drug tests were an important component of the territory's overall approach to reduce incidents of drug driving.