Nothing in sections 4 , 5 and 6 affects –

(a) the right of a person suspected of having committed an offence to refuse to answer questions or to participate in investigations except where required to do so by or under an Act or a Commonwealth Act; or

(b) the onus on the prosecution to establish the voluntariness of an admission or confession made by a person suspected of having committed an offence; or

(c) the discretion of a court to exclude unfairly obtained evidence; or

(d) the discretion of a court to exclude illegally or improperly obtained evidence.