The police can stop you and breath test you at any time using one of the following tests:
Passive breath test: you will be asked to talk into a hand-held device in front of your mount. This shows if you have recently drunk alcohol. If it registers alcohol you will have to take a breath screening test.
Breath screening test: you will be asked to blow into an electronic device which will give a reading for breath alcohol. If it’s high you will need to give an evidential breath sample
Evidential breath test: this electronic device is precisely calibrated to measure breath-alcohol and its result can be used as evidence in court.
Blood test: you may opt to take, or may be instructed to take a blood test in which a medical doctor will test for alcohol and drugs.
If you are suspected of drinking and driving or your signalled to stop at a police checkpoint you can be asked to take a passive breath test, which is the first step. The device will give a result almost immediately and you must wait until the officer has sighted the result and either tells you you can go or indicates that you will need a breath screening test or blood test. In this case you will need to hand over the keys to your vehicle (if asked by the officer), go with them if required, and agree to a blood test.