The Maori Party says it is appalled by the Government's proposed "three strikes" legislation, which has been detailed by the National and ACT parties.
Under the policy, which will need to be approved by Parliament, anyone who commits a third violent crime will receive the maximum possible sentence, with no chance of parole.
Maori Party co-leader and Associate Corrections Minister Pita Sharples says increasing punitive measures does not solve the problem of crime and violence.
He says the proposals will create huge disparities in sentencing and punishment that are completely out of proportion to the crime.
Dr Sharples says it shows the Government is hide-bound by political rhetoric on crime and punishment that has no factual basis.
Law will deter crime - minister
However, Police and Corrections Minister Judith Collins says the proposed legislation will have a definite deterrent effect, in particular because offenders will be given clear warnings.
"Because of the fact that judges will have to give the warning on the first strike, and obviously a second warning on the second strike, they will have to make it very clear to the offenders what is going to happen to them," she told Summer Report.
The ACT party is disputing claims that the proposed law will not reduce crime. Its justice and corrections spokesperson, David Garrett, says in California, where three strikes legislation was implemented in 1994, violent crime has dropped by 60%.
Labour Party leader Phil Goff says projections of a resulting increase in the prison population are far lower than the National Party claimed during campaigning for the 2008 election.
Causes of crime not addressed
The Howard League for Penal Reform's president, Peter Williams QC, says the policy fails to address the underlying causes of crime, which include poverty and alcohol and drug addiction.
He adds that parole can be beneficial by encouraging inmates to reform and to behave in prison, and removing it has potentially dangerous consequences.
The new system would cover 36 serious violent and sexual offences, with maximum sentences ranging from seven years to life.
A first conviction would be treated normally, a second would mean no possibility of a parole, and a third conviction would mean the maximum available sentence must be imposed - also without parole.
The changes will be incorporated into the Sentencing and Parole Reform Bill, and will only apply to those aged over 18 and for offences committed after it has been passed into law.