The Government has tabled legislation that would allow serious sexual or violent offenders to be locked up indefinitely.
The Public Safety (Public Protection Orders) Bill would keep highly dangerous offenders in prison longer than their initial sentence if they were deemed at high-risk of reoffending.
At present, a small number of prisoners - between five and 12 a decade - were released while still at a high risk of committing another crime.
Justice Minister Judith Collins said extended supervision orders, which meant released prisoners were monitored 24 hours a day, did not go far enough.
The bill would allow authorities to apply to the High Court for a public protection order. If successful, it would give Corrections the power to detain a person indefinitely in a flat or residence within prison grounds.
The order would be decided in a civil, not a criminal proceeding, and offenders would be able to request a review of the decision.