The next Victorian government, regardless of who wins office, could be forced to expand or build new jails as the major parties promise to crack down on law and order, adding to an already tight budget.
At the start of the month, the state's prisons were 92 per cent full, with 4,624 people serving a sentence in Victorian jails and another 3,268 on remand.
Reserve capacity is needed to maintain flexibility that ensures certain inmates are not housed together, and to meet increased demand.
But with Premier Ben Carroll introducing tougher laws and the Jess Wilson's Coalition promising to be even tougher on justice, more people are likely to end up in prison.
Building a new prison could cost more than $1 billion — the new 1,292-bed maximum-security Western Plains prison near Lara cost $1.19 billion to build. Its current operational capacity is 1,094.
The dilapidated Port Phillip Prison closed in 2025.
There is also the additional cost of hiring and training new corrections officers, as well as money to increase the capacity of the already overworked courts.
Both sides are also recruiting more police. Jess Wilson is promising an extra 1,500 recruits on top of the 1,500 being sought by the Labor government.
The ABC asked both Labor and the Coalition if it had factored in extra corrections officers and prison space in their crackdown on crime policies.
Neither responded directly to questions about extra costs.
Shadow Police and Corrections Minister Brad Battin said a Liberal and Nationals government would work with Corrections Victoria to manage prisoner numbers within the existing network of facilities.
"Make no mistake, under a Liberal and Nationals government, if you do the wrong thing, there'll be a prison cell and bed ready for you,'' Mr Battin said.
A Labor spokesperson said it had already invested in more than 1,200 additional prison beds, and an extra 1,200 prison officers have been recruited, with $727 million allocated in the 2025-26 state budget.
On Sunday, Mr Carroll promised to spend $204 million to set up a new therapeutic rehabilitation detention program at Malmsbury Youth Justice Centre.
The former chair of the Sentencing Advisory Council, Arie Freiberg, said more police and tougher rules would result in pressure on the prison system, warning it would result in more people being held in police cells.
Dr Freiberg, chair for 18 years from 2004, said the public needed to be aware that there was a high flow-on cost from tougher law and order policies
"It has extensive and expensive consequences down to all other parts of the criminal justice system. And we have to be prepared for that, and we have to pay for that. Justice is not cheap,'' he said.
Dr Freiberg also said law enforcement needed to be based on intelligence, not flooding the streets with more police. He was concerned that a more punitive approach to lower-level offending could place a further burden on the already busy courts.
"We're finding more and more people who are suffering from mental illness, mental disorders, drug-related, alcohol-related crime,'' he said.
"We need to deal with those in a social manner and not through the criminal justice system."
He said investing in those services rather than prisons was far more cost-effective.
Swinburne University law professor Mirko Bagaric said Victoria's crime wave was a direct result of lenient and soft sentencing under the Labor government.
"Crime is solvable,'' he said. "If we need more prisons, then that is a good investment."
Between 2019 and 2025, Victoria's prison population dropped from 8,102 to 5,915, while the crime rate soared.
"We need to lock up those that scare us; not those that annoy us [like property offenders],'' he said,
He said the state needed to make sure the right types of people were being sent to prison; namely violent offenders and sexual offenders.
Dr Bagaric said Melbourne had more firebombings than any other city in the world because there was no serious punishment for the dangerous crime.
Police pledges and protecting Good Samaritans
Labor is also promising to recruit 200 more police reservists to work at police counters in stations as part of its bid to re-open police stations.
As part of the $370 million pledge, Labor is also promising to build or upgrade police stations at Watergardens, Doncaster, Keilor Downs, Greensborough, Moonee Ponds and Clayton.
Ms Wilson is also set to focus on law and order on Monday with a pledge to introduce an "Aidan's Law" in memory of 22-year-old Aidan Becker, who was killed when trying to protect a 14-year-old boy at Mernda state station in March.
The law is designed to ensure courts specifically consider whether an offender has attacked someone acting as a good Samaritan.
The Coalition says the change would explicitly recognise attacks on Samaritans as an aggravating circumstance when determining a criminal sentence.
