The Sentencing Act 2017 (SA) includes two sentencing regimes that allow for the indefinite detention of a sexual offender who is incapable of controlling or unwilling to control their sexual instincts.

Under Part 3 Division 5, the Supreme Court may order indefinite detention when sentencing a person who has been convicted of a relevant sexual offence or on application by the Attorney-General where a person has been convicted and sentenced to a term of imprisonment for a relevant sexual offence, but before they have been released from prison [s 57]. See Indeterminate detention.

From 28 April 2025, under Part 3 Division 2A, a sentencing court must impose indefinite detention when sentencing a serious child sex offender to imprisonment for a triggering child sex offence. See Serious child sex offenders.

Only the Supreme Court can release an offender who has been sentenced to an indeterminate period of detention.