Labour supported the bail changes at the time, which were led by then-Justice Minister Judith Collins and reversed the burden of proof for people accused of serious crimes.
That meant people accused of murder or Class A drug offences or repeat offenders in kidnapping, aggravated burglary and other serious cases had to show why they should be bailed, rather than the police showing why they should be locked up.
Little said the stricter laws had been applied too broadly and had led to a far greater incarceration rate than predicted.
The Ministry of Justice had advised in 2013 that 50 extra prison bed nights a year would be required as a result of the changes. Instead, 800 extra bed nights a year had been required.
"It was meant to apply just to the most serious offences," Little said.
"But actually the people being remanded in custody are across the full range of offences, including things like burglary and other kinds of lower-level offences."
Collins said yesterday that any reversal of her reforms would be a mistake. They were driven by the "very real concerns" that people charged with violent, sexual and drug offences were getting bailed and reoffending, she said.
In particular, there was a concern that methamphetamine manufacturers and domestic abusers were getting bail and reoffending or intimidating their accusers while they awaited trial.
"The public at the time were very pleased that we were taking that step. And the public today will be very unhappy to think that Labour is considering undoing what was an incredibly important step for families of domestic violence in particular."
National's bail reforms occurred against the backdrop of the Christie's Law campaign, named after Auckland teenager Christie Marceau. Marceau was killed by Akshay Chand, who was on bail for kidnapping and assaulting Marceau.
Tracey Marceau, Christie's mother, said she would be "extremely concerned" by any review of National's bail changes, describing them as a "great step forward".
She said they could be more defined, rather than softened, and education could be increased for departments associated with bail decisions.
The unexpected impact of bail laws is one of the factors behind the rising prison population, which has defied official predictions.
Little said another factor was the absence of adequate housing for accused offenders seeking bail, which was making judges hesitant to approve their release into the community.
The prison muster is currently 10,645, leaving just 355 spare beds. It is forecast to rise to 12,000 by 2025.
Little's concerns echo comments from the Prime Minister's chief science adviser Peter Gluckman, which blamed tough-on-crime policies for ballooning prison costs and inmate numbers.
In a report last month, Gluckman's office urged a new "data over dogma" approach to justice, saying offending could be better tackled by investing in interventions, rather than just building prisons.
New Zealand's prison population - 220 out of every 100,000 Kiwis are now behind bars - is among the highest in the developed world.
Corrections is urgently building pop-up jail cells and has sought approval for a 3000-bed mega-prison in rural Waikato. That places Labour in a difficult position because the party has promised to cut the prison population by 30 per cent in 15 years.
Little said Waikeria would definitely be expanded, it is just a matter of by how much. He appeared to downplay the possibility of an expansion to 3000 beds.
"I can't say what the decision is going to be, except to say there are way more options than just the mega-prison concept."
The Government will make a decision on the prison in mid-May, after pushing back the deadline twice.
