Trends in the detention population
The number of young people in detention on an average night is relatively small, and the amount of random variation from quarter to quarter is more noticeable when numbers are small. This might affect the appearance and interpretation of trends, and these should be interpreted with caution (particularly where they relate to small populations).
In this report, comparisons are made between the June quarter 2025 and the June quarter one year earlier (2024) and 4 years earlier (2021). The same quarters are compared across years to minimise the effect of seasonal variation. However, as data on legal status were not available for the Northern Territory between September quarter 2024 and June quarter 2025, sections of this report use the Australia total excluding the Northern Territory for comparison when referring to sentenced and unsentenced groups.
Previous analyses have indicated that there appears to be some seasonal variation in the numbers of young people in sentenced and unsentenced detention each year (AIHW 2025), which is yet to be fully investigated or explained.
This report aimed to summarise key trends over the 1–year and 4–year periods.
For more data, including counts of young people who enter the youth justice system throughout the year, and trends over 10 years to 2023–24, see Youth justice in Australia 2023–24.
Impact of COVID-19 on youth detention data
Measures put in place as part of government responses to COVID-19 during 2020 and 2021 (including travel bans/restrictions, lockdowns limiting non-urgent face-to-face work, remote learning for students and quarantine requirements) may have affected youth detention processes during 2019–20 to 2021–22. The long-term impact of COVID-19 on youth detention processes is still unknown. Comparisons made between the June quarter 2025 and 4 years earlier may be impacted by lower numbers and rates of young people in detention during June quarter 2021.
AIHW (Australian Institute of Health and Welfare) (2025) Youth justice in Australia 2023–24, cat. no. JUV 145, AIHW, Canberra.