Quick answers, state by state

In most Australian jurisdictions, no — presence offences apply regardless of prescription. Tasmania provides a defence for lawful, unimpaired use, and NSW has reform before Parliament. Check your state's page and always verify against official sources.

No. Driving while impaired is illegal in every Australian state and territory, regardless of prescription or registration.

No. Home tests indicate presence status only at a moment in time; they are not proof of fitness to drive, not calibrated to police laboratory thresholds, and not a defence to a charge.

There is no reliable universal window. Oral fluid detection depends on dose, frequency, product type and individual biology — regular patients can test positive well after any impairing effect has passed, sometimes days after the last dose. No app, chart or home kit changes that.

Refusing an oral fluid test when lawfully directed is itself an offence in every Australian jurisdiction, and it is generally penalised at least as severely as testing positive.

Roadside tests target THC, not CBD. However, some CBD products contain small amounts of THC, so check your product's certificate of analysis — and driving while impaired by any medication is an offence everywhere.

No Australian jurisdiction lets a prescription stop the roadside process. Where prescriptions matter, they matter later — as a defence at court in Tasmania, in sentencing discretion in Victoria, or through the proposed NSW registration scheme once (and if) it becomes law.

You are subject to the law of the state you are driving in, not your home state — and penalties, including disqualification, generally follow you home through interstate recognition. Tasmania's defence does not travel with you. See our interstate driving guide.