The national imprisonment rate for June was 207.2 people per 100,000 of population, the lowest in at least three years. The rate began a steady decline in March when the pandemic first took hold, then slid even lower in April, May and June.

The falling imprisonment rate matches the fall in certain crime types across the jurisdictions. In the ACT, all reported crime was down 13.6 per cent from April to June this year compared with the same period last year, with specific violent crimes such as alcohol-related assault falling dramatically.

The latest Corrective Services data provided by the Australian Bureau of Statistics revealed the ACT's June imprisonment rate was 139.2 per 100,000 people, well below the national average and the second-lowest across the country behind Victoria.

However, the average daily number of people held in custody has remained relatively stable with 41,180 behind bars across Australia, including 462 males and females in the the ACT's only prison, the Alexander Maconochie Centre.

In a snapshot provided at June 1 this year the ACT had 450 people in prison, which included 186 held on remand and/or awaiting sentencing. In that snapshot of the prison population, 118 identified as Indigenous.

Canberra's prison has a design capacity of 424 beds with one detainee per cell, with a further 43 beds in special units. In practice, the prison regularly "double bunks" inmates.

Aside from those held behind bars, the ACT also had 929 males and 237 females out in the community and required to comply with corrections orders and/or bail conditions. Both numbers were fewer than in June last year.

The high number of unsentenced prisoners held in Canberra's sole maximum security jail has always been problematic and costly for ACT Corrections to manage.

In the Inspector of Correctional Services' independent report to the ACT Assembly late last year, he found that in the first six months of 2019 the AMC received 373 people on remand and discharged 237.

"In the same period only 40 sentenced detainees were admitted to custody. This throughput - known as "churn" in corrections' jargon - of remandees places an enormous strain on the AMC across a number of areas," his report said.

The activity involved in processing people for short-term custody - those that have been refused bail and are waiting on a court hearing, or are yet to be sentenced - is also hugely expensive to the ACT taxpayer in individual health assessments, transport costs, induction processes and provision of clothing.