POST BAIL – America’s justice system runs on the exchange of money for freedom. Some say that’s unfair. But can data fix it?

JERSEY CITYN.J. ─ On the ground floor of a deteriorating county courthouse, in a room outfitted with temporary office furniture and tangles of electrical wires, a cornerstone of America’s criminal justice system is crumbling.

A 20-year-old man in a green jail jumpsuit appears on a video monitor that faces a judge. It is early June, and he has been arrested for driving a car with a gun locked in the glove compartment.

If he were in almost any other courtroom in the country, he’d be ordered to stay behind bars until he posted bail — if he could afford it. This is what millions of people charged with crimes from shoplifting to shootings have done for more than two centuries. The bail system, enshrined in the Bill of Rights, is meant to ensure that all defendants, presumed innocent before trial, get a shot at freedom and return to court.

But allowing people to pay for their release has proved unfair to people who don’t have much money. The poor are far more likely to get stuck in jail, which makes them far more likely to get fired from jobs, lose custody of children, plead guilty to something they didn’t do, serve time in prison and suffer the lifelong consequences of a criminal conviction. Those who borrow from a bail bondsman often fall into crippling debt.

At the same time, the wealthy can buy their way out of pretrial detention on just about any offense, including murder.

The bald inequity of this system has triggered a national movement to eliminate bail altogether.

But what to replace it with?

In New Jersey, the answer is an algorithm, a mathematical formula to determine whether someone is likely to return to court for trial or get arrested again.