Crimes Act 1914

A constable may, without warrant, arrest a person for an offence (other than a terrorism offence and an offence against section 80.2C of the Criminal Code) if the constable believes on reasonable grounds that:

the person has committed or is committing the offence; and

proceedings by summons against the person would not achieve one or more of the following purposes:

ensuring the appearance of the person before a court in respect of the offence;

preventing a repetition or continuation of the offence or the commission of another offence;

preventing the concealment, loss or destruction of evidence relating to the offence;

preventing harassment of, or interference with, a person who may be required to give evidence in proceedings in respect of the offence;

preventing the fabrication of evidence in respect of the offence;

preserving the safety or welfare of the person.

If:

a person has been arrested for an offence under subsection (1); and

before the person is charged with the offence, the constable in charge of the investigation ceases to believe on reasonable grounds:

that the person committed the offence; or

that holding the person in custody is necessary to achieve a purpose referred to in paragraph (1)(b);

A constable may, without warrant, arrest a person whom he or she believes on reasonable grounds has escaped from lawful custody to which the person is still liable in respect of an offence.