A growing majority of Maine’s county jail inmates have not been convicted of a crime and pose little risk to the community. So why are they sitting in a jail cell, costing taxpayers $100 a day or more?

The answer has to do with the ineffective bail system used here and in most other states, as well as with the court system’s institutional reluctance to adopt new standards.

There is hope that the tide is changing, however, both in Maine and across the country. A commission here is reviewing the issue as part of an effort to solve the budget crisis at Maine’s 15 county jails, which are facing a 75 percent revenue shortfall.

The commission, by way of its eventual recommendation, could help the state take a step toward changing a system that costs taxpayers millions and unnecessarily jails thousands of Mainers charged with petty crimes.

Fifteen years ago, less than half of the state’s county jail inmates were there awaiting trial. In the next decade, as the overall jail population surged, so too did the pretrial population, only at a higher rate. The total number of inmates increased 89 percent in those 10 years, and by 2007, more than 60 percent of inmates were awaiting trial. Today, that it is closer to 75 percent.

The same holds true nationwide, where 62 percent of inmates are being held pretrial, up from 56 percent in 2000.

The main factor keeping pretrial inmates behind bars — both in Maine and throughout the United States — is money. Most of the accused can’t meet even the low bail that comes with charges related to minor, nonviolent crimes.

So the defendants await trial in jail, at a significant financial and social cost. Nationally, $9 billion a year is spent on housing pretrial inmates, and even short stints of detention disrupt work, education and family life. Life is made significantly harder for the defendant upon release, and recidivism rates increase by as much as a factor of four.

On the other hand, there is a risk to letting a defendant go without bail. The trick is to get that risk as low as possible, using assessment tools that factor in criminal history, substance abuse, housing and mental health, among other criteria.

Pretrial services that are now done on a limited basis in Maine help courts determine which defendants can be released, and whether bail and supervision are appropriate.

The savings are significant. At a commission meeting last week, Capt. Marsha Alexander, the Kennebec County jail administrator, said her facility saves about $2 million a year from fewer prisoners as a result of pretrial screenings, at a cost of $130,000.

And the assessments now being used nationwide are accurate enough so that public safety does not suffer. Research shows that when proven assessment tools are applied correctly, defendants deemed to be a low risk very rarely commit an offense while free.

Maine needs to develop, test and implement a uniform assessment tool successfully in all county court systems. A pilot project developed at Two Bridges Regional Jail in Wiscasset aimed to do just that, but the project failed to spread to other counties.

That’s where the commission comes in. The Board of Corrections should be given the authority and resources to find the right assessment tools, put them in place statewide and put an end to the wasteful spending.