139Cautioning of persons

139 Cautioning of persons (1) For the purposes of section 138(1)(a), evidence of a statement made or an act done by a person during questioning is taken to have been obtained improperly if— (a) the person was under arrest for an offence at the time; and (b) the questioning was conducted by an investigating official who was at the time empowered, because of the office that he or she held, to arrest the person; and (c) before starting the questioning the investigating official did not caution the person that the person does not have to say or do anything but that anything the person does say or do may be used in evidence. (2) For the purposes of section 138(1)(a), evidence of a statement made or an act done by a person during questioning is taken to have been obtained improperly if— (a) the questioning was conducted by an investigating official who did not have the power to arrest the person; and (b) the statement was made, or the act was done, after the investigating official formed a belief that there was sufficient evidence to establish that the person has committed an offence; and (c) the investigating official did not, before the statement was made or the act was done, caution the person that the person does not have to say or do anything but that anything the person does say or do may be used in evidence. (3) The caution must be given in, or translated into, a language in which the person is able to communicate with reasonable fluency, but need not be given in writing unless the person cannot hear adequately. (4) Subsections (1), (2) and (3) do not apply so far as any Australian law requires the person to answer questions put by, or do things required by, the investigating official. (5) A reference in subsection (1) to a person who is under arrest includes a reference to a person who is in the company of an investigating official for the purpose of being questioned, if— (a) the official believes that there is sufficient evidence to establish that the person has committed an offence that is to be the subject of the questioning; or (b) the official would not allow the person to leave if the person wished to do so; or (c) the official has given the person reasonable grounds for believing that the person would not be allowed to leave if he or she wished to do so. (6) A person is not treated as being under arrest only because of subsection (5) if— (a) the official is performing functions in relation to persons or goods entering or leaving Australia and the official does not believe the person has committed an offence against a law of the Commonwealth; or (b) the official is exercising a power under an Australian law to detain and search the person or to require the person to provide information or to answer questions.