These may seem like minor tweaks to pointlessly long sentences, and for the most part they are. But when half of all federal inmates are in for drug crimes, even small changes can make a real difference.

In addition, the bill would give federal judges more power to impose sentences below the mandatory minimum in certain cases, rather than being forced to apply a strict formula. This would shift some power away from prosecutors, who coax plea deals in more than 97 percent of cases, often by threatening defendants with outrageously long punishments.

Other provisions would give more inmates the chance to earn early release by participating in educational and other rehabilitative programming; seal or expunge juvenile records, so people are not burdened for life because of crimes they committed when they were young; and make it easier for older inmates to seek early release — a smart idea because they are by far the costliest to keep imprisoned and the least likely to commit new crimes.

Finally, and critically, many parts of the bill are retroactive, which means thousands of current federal inmates could benefit immediately. In particular, 6,500 prisoners are still serving time under an old law that punished crack-cocaine offenses far more severely than powder-cocaine offenses. When the law was altered to reduce the disparity in 2010, the change applied only to new cases, leaving thousands of inmates serving unjustly long sentences for no good reason.