AMERICA incarcerates people awaiting trial at triple the world average. Every day, roughly 500,000 people who have been convicted of no crime sit in county jails. Some are there because a judge determined they were too dangerous to return to the streets. But the vast majority end up behind bars because they could not afford to post “bail”, a returnable payment designed to ensure they’ll show up for their court dates. In practice, this means that wealthy people like Bill Cosby (who wrote a quick check for $1m yesterday after being charged with sexual assault) remain free before their trials while the poor are locked up. Money buys all kinds of things, so it is not surprising that people who have been charged with crimes do better when they have more of it. There are rather stark inequalities introduced by most states’ money-bail system, as an episode of apparent racial bias in the criminal justice system suggests. When Sandra Bland, a black woman, was pulled over in Texas last July for changing lanes without signaling, a judge set her bail at $5,000. She did not have the money, and could not come up with the $500 she would have had to pay a bail bondsman to post the bail for her. So she went to jail, where she was found dead by apparent suicide three days later.

Not all indigent individuals charged with crimes have such tragic endings. But cash-bail brings serious harm to thousands of Americans every year. A class-action lawsuit filed in October by Equal Justice Under Law, a non-profit civil rights organisation, details the negative impact of San Francisco's antiquated “bail schedule” regime according to which a specific bail is matched to a particular crime, with no accounting for extenuating circumstances or the wealth of the accused. The city’s “wealth-based pretrial detention scheme...operates to jail some of San Francisco’s poorest residents solely because they cannot pay an arbitrary amount of money”, the lawyers at Equal Justice Under Law contend.

The lawsuit tells the stories of two individuals, both of whom “represent a class of similarly situated people”. An indigent 19-year-old resident of Oakland, Riana Buffin, had her bail set at $30,000 after being charged with grand theft of personal property and conspiracy. Ms Buffin, who earns an hourly wage of $10.25, lives with her disabled mother and tends to three younger brothers, including two with severe disabilities. Another plaintiff, Crystal Patterson, was arrested in late October and charged with assault, a crime carrying a bail of $150,000. Ms Patterson supports herself and her grandmother on an hourly wage of $12.50 as an in-home care worker. Neither Ms Buffin nor Ms Patterson could afford to pay the bail, and neither could afford to leave their families in the lurch by going to jail for at least two days before their trials begin. Charges against both women were dropped a few days after the lawsuit was filed, but Ms Patterson owes $15,000 to a bail-bond company that posted bail for her.

A similar conundrum means that around 1,800 San Franciscans every year are detained before their trials because they are poor. This violates the 14th Amendment, the lawsuit reads: the due-process and equal-protection guarantees “have long prohibited imprisoning a person because of the person’s inability to make a monetary payment”. Yet that is just what San Francisco’s bail schedule does. Even the city’s former sheriff, Ross Mirkarimi, laments the injustice and inefficiency of its bail policy. Most inmates in its jails have been charged with minor crimes or misdemeanors like public urination or petty larceny and are at scant risk of ducking their trials and compounding their legal woes. Jailing these people before their trials costs the city. It would be cheaper and more humane, he suggests, to use pre-trial services like electronic monitoring to usher defendants back to court. To take the accused out of their homes and away from their jobs, Mr Mirkarimi notes, “furthers the destruction and ruination of people and families in San Francisco”.

Few people outside the rather brazen bail-bond industry have nice things to say about the present system. The American Bar Association urges judges to ask for cash bail "only when no other less restrictive condition of release will reasonably ensure the defendant's appearance in court". Bail systems like the one being challenged in California also have the perverse effect of encouraging some innocent defendants to falsely claim guilt in a plea bargain. It can be less costly and quicker to confess to a crime rather than to languish in jail or go into debt in hopes of being found not-guilty. In the long term, though, having a conviction on your record damages job prospects. It also undermines the very purpose of a criminal justice system: identifying criminals, and punishing them appropriately.