In 2014, New Jersey voters agreed there was a problem with their state's criminal justice system. Because it relied so heavily on bail, poor defendants who posed little risk of danger or flight were often held in jail, simply because they couldn't afford even a modest amount of bail. One study found 12 percent of the people in jail in New Jersey were being held for less than $2,000 bail.

So voters passed a new law, which went into effect on New Year's Day, to encourage judges to see bail as a last resort. Judges can still release someone based on their own recognizance, or they can release them with non-monetary conditions — such as wearing an ankle bracelet, or weekly check-ins. They'll be guided by an assessment tool that considers each individual's risk of returning to court or committing another crime based on their criminal history, age and the nature of the alleged crime.

Glenn Grant, administrative judge for New Jersey courts, said the new system is much more objective and rational.

"If you have a money-based system and you have individuals who pose a risk to further community violence that have access to money, then you're losing out on both ends," he explained. "You're not creating a safer system for individuals and you're also not creating a fairer system."

Judges can still impose bail if the tool predicts someone is at a risk of flight. They can also refuse to release someone if they think they're dangerous. And prosecutors will weigh in.

The Public Safety Assessement tool, now being used by New Jersey, has been tried in other states and cities. It was developed using data from 1.5 million pretrial records in 300 jurisdictions across the United States, according to the Laura and John Arnold Foundation. The tool helps predict which defendants pose the greatest risks.

Cherise Fanno Burdeen, C.E.O. of the Pretrial Justice Institute, said there's no evidence that releasing more defendants leads to more crime.

"There's no empirical evidence that money works," she said, referring to bail. "What’s happening now is that people are getting out simply based on the ability to pay."

She said the tool has been effective in Washington, D.C., North Carolina and Kentucky. 

However, there are costs to this system. New Jersey counties unsuccessfully tried to delay its implementation, fearing it would require more staffing and resources. For those who are held in jail, the new law also requires speedier trials. 

The state has allocated money to pay for 20 additional judges. Burdeen said the new law could also help pay for itself.

"We expect to see that jail populations of low risk and medium risk pretrial defendants in New Jersey will go down," she said. "And we know that jail costs per day far exceed the amount of money that it costs to operate a pretrial justice system that follows both the law and science."

Dennis Braithwaite, a Rutgers Law Professor and former New Jersey judge, said he supports the new system because it gives judges more discretion. Previously, they weren't allowed to withhold bail — even if someone was charged with a horrendous crime. As a solution, he said, judges would "set the bail so high that he or she can't meet the bail so they stay in jail."

But now, he said, judges can tailor pre-trial services for each defendant. "Maybe they report to some sort of probation officer or court official weekly," he said. "You might impose on them a requirement to continue working if they have a job, or if they don't have a job."