The answer to this question all depends on what state you live in. For New South Wales, you have to have been driving a vehicle in the past two hours in order for a police officer to be allowed to request a breath test. This same law applies to Queensland as well. If you reside in Victoria it is a little different, a police officer can’t request a breath test from you if you have not been driving in the past three hours. For the Northern Territory and Western Australia the period of time is four hours.
Within all states of Australia, if you are at home, a police officer is not allowed to request that you undergo a breath test analysis.
There are laws which allow a breath test to be refused for medical reasons but if a doctor states that completing the breath test won’t affect the health of the individual then the test is allowed to be conducted. In summary, if you are going to refuse a breath test for medical reasons you should already have a certificate “in the approved form” from a doctor stating that because of a stated illness or disability, you are incapable of providing a breath or saliva specimen.
Within Queensland, this is explained as, “immediately after the requirement (for a breath test) is made, the person produces to the police officer a certificate in the approved form from a doctor stating that (i) because of a stated illness or disability, the person is incapable of providing a specimen of breath, a specimen of saliva or both a specimen of breath and of saliva; or (ii) the provision of a specimen of breath, a specimen of saliva or both a specimen of breath and of saliva could adversely affect the person’s health; or the person satisfies the justices that the requisition to provide a specimen of breath, a specimen of saliva or both a specimen of breath and of saliva was not lawfully made or that the person was, by reason of the events that occurred, incapable of providing the specimen as required or that there was some other reason of a substantial character for the person’s failure to provide the specimen as required other than a desire to avoid providing information that might be used in evidence.”
Now, in saying all of that, if you do have a medical certificate that prevents you from needing to complete a breath test, the police officer will require a blood test from you instead, for example as per the Queensland Transport Operations (Road Management) Act, section 8E ‘Specimen of blood must be required if doctor’s certificate produced’.