South Australia · Learner's Theory Test · Road rules

How much THC (cannabis), methamphetamine, MDMA or cocaine needs to be detected in a roadside saliva test for you to commit a drug-driving offence?

The answer

Any detectable amount at all Correct
It is only an offence if you also crash
Enough to clearly impair your driving
An amount above a prescribed legal concentration, like alcohol

Why that's the answer

Unlike drink driving, there is no legal threshold for these drugs - the presence of any detectable amount in your saliva is an offence. SA Police roadside tests detect THC, methamphetamine, MDMA and cocaine.

Where this rule comes from

Department for Infrastructure and Transport – The Driver's Handbook Official source

Take the full South Australia practice test (50 questions)

More SA Learner's Theory questions

Same topic first — road rules trips up more learners than any single rule.

Ready for the road?

Once you pass your Learner's Theory Test, you'll need 75 supervised hours in South Australia. Find an instructor with transparent pricing and live availability.

Find a driving instructor near you