David Cameron wants to change the way prison custody works to tackle an "out of sight, out of mind attitude". Here are some of the ideas already causing controversy.
One proposal to tackle overcrowding is to allow some prisoners out on weekdays - as long as they are tagged - so they would only be behind bars at weekends.
This would not include serious and violent criminals, but prisoners who are not considered a serious threat to the public and are nearing the end of their sentence.
It is thought it would help them adjust to normal life before their full release.
Pregnant women who give birth while in prison are usually transferred to an internal mother and baby unit for an initial period.
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:: How would the pilot tagging scheme work?
GPS technology would allow criminals to be electronically monitored around the clock, allowing officials to pinpoint their exact location.
It would include prisoners on temporary or weekday release, as well as those serving community service - subject to supervision.
It would allow police and probation workers to check if offenders are sticking to the terms of their release.
One condition could see offenders banned from drinking alcohol and fitted with tags that detect when they have had a drink.
Governors at six so-called "reform prisons", to be established by the end of the year, will be able to manage their own budgets and have control over the way they run their jails.
The scheme could then be included in a new Prisons Bill and roll out across many of Britain's 121 jails.
New league tables will be introduced to show which prisons have the best rehabilitation rates.
:: How many people are in prison?
The latest figure is 85,634 - of which 81,814 are men and 3,820 women.
A year ago, the prison population was 85,280.
Ten years ago it surpassed 80,000 for the first time.
:: Why are prisons so overcrowded?
Judges are under pressure to give custodial sentences.
The rehabilitation of prisoners is made all the more difficult in crowded prisons, so re-offending increases and a vicious circle develops.