A single legal change has caused massive growth in the prison muster.

Growth in New Zealand's prison population has accelerated.

The recent spike can be traced back to changes to bail laws in 2013.

Since then, people charged with violent, sex or drug crimes have to prove they pose no danger to the community to get bail.

If they can’t, they stay behind bars.

The changes followed shock over the 2011 killing of 18-year-old Christie Marceau.

Her killer Akshay Anand Chand was on bail when he killed her.

Chand was found not guilty of her murder by reason of insanity.

When the bail law was changed, Labour said it was “a fairly soft measure” which would require a further 50 prison beds.

In fact, the number of prisoners awaiting trial or sentencing has almost doubled.

Remand prisoners now make up almost 30 per cent of the prison population.

And our prisons are bursting at the seams.

“Our prison system is in chaos, and in crisis, at the moment.”

– Justice Minister Andrew Little

It leaves Justice Minister Andrew Little with a tough decision. Roll back popular changes to the bail laws or build another expensive prison.