The old expression about public policy sometimes acting like a pendulum — swinging one way, then back the other way — comes to mind when reading about a plan by federal officials to release 6,000 prisoners next month, ahead of their original sentences.

The plan is the result of a rethinking about mandated minimum sentences and a tough-on-crime political culture of the 1980s and 1990s that resulted in hundreds of thousands of nonviolent criminals, mostly drug offenders, serving lengthy prison sentences.

In a rare example of bipartisan agreement, many Democrats and Republicans agree that the mandatory sentencing, especially for nonviolent drug crimes, was not effective or fair — and was costing taxpayers billions of dollars.

Many of the drug offenders do not pose a threat to society and don’t need to be in prison.

Former Attorney General Eric Holder advocated for rolling back strict mandatory sentences for nonviolent crimes and releasing thousands of federal prisoners who have served most of their sentences.

The same eventually could happen in state prisons, which house far more people than federal prisons. Federal prisons house about 220,000 inmates, while state prisons hold closer to 1.4 million prisoners.

However, action in states will have to come from state legislatures, one state at a time.

Inmates convicted of violent crimes represent about 54 percent of all state prisoners, based on data from the prison population in 2012. More than half of federal prisoners in 2012 were drug offenders. The nonviolent drug offenders are the target population for early release.

The federal action, reported this week by the Associated Press, will begin with a release of 6,000 prisoners early next month.

The partial reversal of tough, mandatory sentences for nonviolent drug offenders is sensible and overdue. The unusual bipartisan agreement comes from liberals seeing the social costs to families of putting people in prison for nonviolent drug crimes while conservatives more often focus on the financial burden of housing millions of inmates unnecessarily.

The swinging pendulum image comes to mind with the report that about 100 of the 6,000 prisoners scheduled for early release were not merely drug offenders.

Analysis of records by the AP revealed that some of the soon-to-be-released prisoners had automatic weapons when they were caught by police or had past convictions for robbery, assault and international heroin smuggling.

Judges must approve any prisoner granted early release, and the inclusion of more than just ordinary drug offenses among those scheduled for early release suggests judges should be careful and consider a prisoner’s entire criminal record.

A violent crime committed by a recently released federal prisoner could trigger a public reaction or backlash that would endanger the program, which would be unfortunate.

Studies suggest that prisoners released a few years short of their full sentence are no more likely to commit new crimes that those who serve a few more years.

Still, the early release program is an experiment and the records of those released early should be carefully examined.

The United States imprisons a larger percentage of its population than any other advanced nation, which raises questions and suggests a need for change, particularly when it comes to drug crimes.

And the financial burden on taxpayers funding the state and federal prison systems cannot be ignored.

It’s a good thing for the pendulum to swing away from overly long sentences for nonviolent drug offenders. But the pendulum reversal should not go so far as to release dangerous prisoners.