Prisons are not the Tardis - when they fill up, then what do we do? We have to start letting people go.

Back in 2009, the Chief Justice, Dame Sian Elias, gave a speech on criminal justice matters that caused a brief flurry of excitment and earned her a slap-down from the Minister of Justice, Simon Power. (I posted on it at the time here.)

The bit that got the most attention was this paragraph:

My last suggestion may be controversial. I do not know whether it is practical or politically acceptable, but I think it needs to be considered. We need to look at direct tools to manage the prison population if overcrowding is not to cause significant safety and human rights issues. Other countries use executive amnesties to send prisoners into the community early to prevent overcrowding. Such solutions will not please many. And I am not well placed to assess whether they are feasible. But the alternatives and the costs of overcrowding need to be weighed.

At the time, Simon Power was very quick to dismiss any suggestion that his Government might even contemplate such a policy. And fair enough, too - New Zealand is not (yet) at the point where the conditions in our prisons are such that the safety and human rights issues she refers to demand such actions be taken.

However, this decision of the US Supreme Court rather bears out Dame Sian's warning about where you end up if you keep jamming more and more people into jail. Its just ordered California to release more than 30,000 prisoners, to bring its prison population down to a mere 137.5% of capacity. That's right - even after letting the population equivalent of Blenheim out the doors, California's prisons will still contain far, far more prisoners than they were built to hold.

Which suggests two things to me. Using US penal policy as a model for New Zealand carries costs that will only become apparent in the future. And putting people in prison for having or selling drugs is a really, really dumb idea.