Under S6D(1) RTA 1988, when may a constable arrest without a warrant after a preliminary breath or drug test?

• A. The constable reasonably suspects that the proportion of alcohol exceeds the prescribed limit or that the person has a specified drug exceeding the prescribed limit.
• B. The driver refuses the test with no excuse.
• C. The driver is not driving a vehicle.
• D. The test is inconclusive.

Answer: (B)

The key idea is that the arrest power without a warrant kicks in when a driver refuses to take the preliminary breath or drug test, and does so without a reasonable excuse. If someone declines to provide a sample, the constable may arrest at once to enable an evidential test to be carried out and to secure the evidence needed for the offence.

If the driver’s test result is inconclusive, or if the driver hasn’t refused but simply is suspected of being over the limit, those situations don’t by themselves create the automatic warrantless arrest. The same applies if the driver isn’t driving a vehicle. The act of refusing with no excuse is the specific trigger that allows immediate arrest.