ACT politicians have been urged to consider new crime prevention and rehabilitation measures as an alternative to expanding the territory's only adult jail.
A broad-ranging ACT Assembly inquiry was announced on Tuesday into sentencing in criminal courts.
Community groups have already warned that new measures need to be taken or the 300-bed Alexander Maconochie Centre will have to be enlarged .
The ACT's Alcohol, Tobacco and other Drug Association, Council of Social Service and Mental Health Community Council made the warning in a recent submission to a federal parliamentary inquiry into ''justice reinvestment''.
Justice reinvestment can include prevention, early intervention, diversionary and rehabilitation measures.
''The ACT is in a situation where the territory's only adult prison is at capacity, and decisions need to be made either to reduce the prison population or to invest in the building of new facilities to cater for an increase in the prison population,'' the three groups said.
''Consequently, the ACT is in a prime position to benefit from initiatives that help to reduce prison populations. Justice reinvestment may provide an opportunity to reduce future growth in prison expenditure by removing the need to build new facilities.''
The submission said any measures would have to be carefully developed before adoption.
The ACT Assembly's Justice and Community Safety Directorate plans an 18-month inquiry into how punishments are handed down in Canberra. It would look into timeliness in sentencing and the rates of successful appeal.
The ACT Law Society supported the investigation, but president Noor Blumer cautioned against comparisons with other jurisdictions. ''The vastly different social demographics between, say, the Northern Territory and the ACT make it difficult to draw meaningful conclusions from differences in the type, length and effect of sentences,'' Ms Blumer said.
''That comparisons with other states can be misleading was identified by the ACT Law Advisory Council in its 2011 review of suspended sentences.''
ACT Bar Association president Greg Stretton, SC, said there were limitations to the available data, including issues of sentencing comparability among jurisdictions.
''It is important to analyse and take a considered evidence-based view on the efficacy of court work in sentencing and that a public eye be cast on the way in which the court fulfils its role and the practical working of the legislation in the ACT,'' Mr Stretton said.
Attorney-General Simon Corbell welcomed the inquiry and said a new sentencing database was being rolled out in the Supreme Court that would make it easier to collate information on sentencing trends.