Age limits

In Australia, young people may be charged with a criminal offence if they are aged 10 or over. Separate justice systems operate for young people and adults, each with specific legislation. The upper age limit in the youth justice system is 17 (at the time of the offence) in most states and territories. Those aged 18 or over are dealt with under criminal legislation relating to adults.

In Queensland, legislation to increase the youth justice age limit to 17 was passed in 2016, and was enacted in February 2018. Before then, the age limit in Queensland was 16, and young people aged 17 or over were treated as adults.

From February 2018, young people aged 17 in Queensland were transferred from the adult justice system into the youth justice system. This initially led to an increase in the number of young people held in youth justice detention in Queensland and the national detention rate.

In 2020–21, about 26% of young people under supervision on an average day were aged 18 or over (AIHW 2022). Reasons for this include:

  • young people may be apprehended for an offence that was committed or allegedly committed when they were aged 17 or younger
  • young people may continue to be supervised by the youth justice system once they turn 18 (or they may be transferred to the adult correctional system)
  • some young people aged 18 or over are supervised by youth justice agencies due to their vulnerability or immaturity (in some jurisdictions)
  • young people aged 18–20 in Victoria who appear in courts other than the Children’s Court may be sentenced to detention in a youth facility rather than an adult prison if assessed as suitable and the court deems this appropriate. This is known as the ‘dual track’ sentencing system.

In this report, the term ‘young people’ is used to refer to individuals aged 10 and over who are supervised by a youth justice agency. Numbers of young people in detention relate to young people of all ages unless otherwise specified.

Population rates allow for the comparison of different groups while taking into account different population sizes. In this report, rates are calculated only for young people aged 10–13, 14–17 and 10–17, as these are the key populations in most states and territories (see ‘Technical Notes’ for more information about the calculation of rates).

For this report, the age on an average night each quarter is calculated based on the age a young person is each night that they are in detention. If a young person changes age during a period of detention, then the average nightly number in detention will reflect this.

Average nightly data broken down by age will not be comparable to Youth detention population in Australia releases prior to 2020. For more information about the calculation of age, see ‘Technical Notes’.