A familiar debate amongst summary-jurisdiction-practitioners is if an accused is entitled to a caution against self-incrimination before being questioned about a summary offence. While there’s always been a judicial discretion to exclude evidence unfairly obtained, there’s only an actual statutory requirement for the police to give a caution for a summary offence in very limited circumstances.

Section 464(3) Crimes Act 1958 provides:

(3) Before any questioning (other than a request for the person’s name and address) or investigation under subsection (2) commences, an investigating official must inform the person in custody that he or she does not have to say or do anything but that anything the person does say or do may be given in evidence.

In custody is defined at s 464(1):

464. Definitions

(1) For the purposes of this Subdivision a person is in custody if he or she is-

(a) under lawful arrest by warrant; or

(b) under lawful arrest under section 458 or 459 or a provision of any other Act; or

(c) in the company of an investigating official and is—

(i) being questioned; or

(ii) to be questioned; or

(iii) otherwise being investigated—

to determine his or her involvement (if any) in the commission of an offence if there is sufficient information in the possession of the investigating official to justify the arrest of that person in respect of that offence.

When police are investigating a person and they have the lawful ability to arrest that person for the crime they’re investigating, s 464(3) obliges them to caution the person. But in many summary offence investigations there is no power of arrest available to the police. Section 458(1) of the Crimes Act 1958 limits the circumstances of arrest for summary offences. If there’s no power to arrest under s 458 (or another specific arrest power), there’s no statutory obligation to caution under sub-ss 464(1) and (3).

Section 139 of the new Evidence Act 2008 will require a caution to be given in some circumstances even where no power of arrest exists, or else risk the evidence obtained being excluded in the operation of judicial discretion under s.138.

Section 139(2) states,

(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.

Section 138 reads,

138. Exclusion of improperly or illegally obtained evidence

(1) Evidence that was obtained-

(a) improperly or in contravention of an Australian law; or

(b) in consequence of an impropriety or of a contravention of an Australian law-

is not to be admitted unless the desirability of admitting the evidence outweighs the undesirability of admitting evidence that has been obtained in the way in which the evidence was obtained.

Under these new provisions, a suspect is still entitled to a caution when under arrest or the investigating official possesses a power of arrest. But under sub-s (2), a caution will also be required where the investigator reasonably believes that an offence has been disclosed. Unlike sub-s 458(2), council by-laws and regulations are not expressly excluded from the definition of offence in the Evidence Act 2008.

Where this isn’t done, a presumption against admission of the evidence will activate. The Court will then only receive the evidence if satisfied that the desirability of its admission outweighs the undesirability of the non-compliance.

Charges laid after 1 November 2009 will be subject to the new provisions, so we shouldn’t have long to wait to find out how they’ll be interpreted.