Victoria's prison population has swelled to more than double in recent years, as inmates spend more time behind bars for serious offences, according to the state's Sentencing Advisory Council.
An analysis of trends over the past 20 years shows offenders are spending more time in prison than they were two decades ago, with murder sentences jumping up five years between 2002 and 2020 to an average sentence of 24.5 years.
People found guilty of incest are being put behind bars for an average of nearly 10 years, compared with six years in 2003, according to a Sentencing Advisory Council report.
The shift towards inmates spending more time behind bars goes some way to explaining the surge in Victoria's prison population, council chair Emeritus Professor Arie Freiberg said.
"This is almost certainly because courts are responding to a raft of legislative reforms as well as changing community attitudes," he said.
But the bolstered population is largely down to changes in Victoria's bail and parole laws, Prof Freiberg said.
The state's courts are also more likely to send offenders to jail for serious offences in 2022 than they were 20 years ago.
For instance, the imprisonment rate for cultivating a commercial quantity of narcotic plants has risen from 67 per cent in 2003, to almost 100 per cent over the past five years.
"The increase in Victoria's prison population is in no small part because more people are being held on remand and because more people are receiving short prison sentences," the sentencing council's report said.
However, the number of people being sentenced for serious offences in Victoria has declined overall, with serious injury offences dropping from 170 to fewer than 50.
In 2000, 67 in every 100,000 Victorians were in prison. By 2019, that had increased to 123 in every 100,000.
The state government has a strong focus on tackling the root causes of offending through early intervention, a spokesman said.
"We're delivering a correctional system that keeps Victorians safe, and helps prisoners break the cycle of reoffending and gets their lives back on track," the spokesman said.
"Rehabilitation and reintegration programs play a vital role in helping to break the cycle of re-offending. That's why we have delivered support programs across the correctional system in partnership with community and external organisations."
Victoria has the second-lowest imprisonment rate of all Australian jurisdictions, and the lowest proportion of Aboriginal prisoners in custody of any jurisdiction, according to a Productivity Commission report.
The Victorian budget for 2022 to 2023 allocates more than $76 million in funding towards programs that address reasons why people commit crimes.
The budget also includes funding for expanding after-hours assessment, bail and Children's Court services.
The rate of former prisoners returning to jail in Victoria under sentencing within two years has been lower than the national rate for five consecutive years.
