Land Transport Act 1998, s 64(1)-(1B)
Refusing a blood test for health reasons – It’s a defence to a charge of refusing to have a blood test if the test would’ve been harmful to your health. You’ll need evidence from a doctor to establish this defence.
Taking drugs on doctor’s instructions – It’s a defence to a charge of driving while impaired by drugs if you had a doctor’s prescription for the relevant drug or medicine or a doctor gave it to you, and you followed all the doctor’s instructions.
Refusing impairment test because of disability or injury – It’s a defence to a charge of refusing or not doing a drug impairment test if you weren’t able to take the test because of a pre-existing medical condition or disability, or because you were injured in the traffic accident that led to the police asking you to do the test.