If you're convicted of a criminal offence, and you serve your sentence, that's it, right? You've done your time, paid your debt to society, and they can't punish you any more. That's what the longstanding protections against retroactive penalties and double jeopardy - now encoded in our Bill of Rights Act - mean, right?
Not when National is in power. Faced with a deeply unpopular (and unpleasant) man being released from prison at the end of his sentence, they're legislating to allow him to be detained indefinitely.
The full bill is here. It allows people convicted of a serious sexual or violent offence to be detained in a "residence" on prison grounds under effective house arrest, their mail censored, their phone calls bugged, forced to obey every petty whim of the guards, on pain of random strip searches, solitary confinement or restraint. Which sounds a lot like prison, except the prisoners are kept in houses rather than cells. Though if the government decides that it can't be bothered with the semantic pretence, it can simply detain these people in prison instead. And this despite people having completed their sentence and served their time.
Its an explicit breach of the Bill of Rights Act, of Article 15 of the International Covenant on Civil and Political Rights, and of long-established legal principles. And the government admits this. The Regulatory Impact Statement on the bill [PDF] repeatedly notes that the legislation "is likely to be inconsistent with the BORA and... international obligations" and that it is likely to be found (by both NZ courts and the Un Human Rights Council) to be a retroactive punishment, double jeopardy, and arbitrary imprisonment. The Attorney-General's BORA-vet is as-yet unavailable, but its hard to imagine him disagreeing with that assessment. Despite that, National will ram it through anyway. Which is just another reminder that Parliament does not take its obligations under the BORA seriously, and that we should take the job off them and give it to the courts.