During his State of the Union address in February, Donald Trump introduced Matthew Charles, who in 1996 was sentenced to 35 years in federal prison for selling 216 grams of crack cocaine and illegally possessing a gun. Charles, now in his 50s and a free man, was an early beneficiary of the FIRST STEP Act, which Trump proudly signed into law last December. Among other things, that law retroactively applied crack penalty reductions that Congress approved in 2010.

According to a new report from the U.S. Sentencing Commission, more than 1,000 other federal prisoners have benefited from that provision, receiving sentence reductions of about 30 percent on average. That fact is both a heartening illustration of what can be achieved by bipartisan sentencing reform and dispiriting evidence of how hard it is to take even modest steps toward making the criminal justice system less mindlessly punitive.

This particular step is a belated attempt to implement a consensus that emerged years ago about the unjust and irrational legal distinction between two forms of cocaine. In 1986, amid a panic about the “crack epidemic,” Congress enacted mandatory minimum sentences that treated the smoked form of cocaine as if it were 100 times worse than the snorted kind.

Congress decreed that people caught with five grams or more of crack, equivalent to as few as 10 doses, would be subject to a five-year mandatory minimum. That’s the same as the penalty for 500 grams or more of cocaine powder, which amounts to thousands of doses. Likewise, Congress made the penalty for 50 or more grams of crack (100 to 500 doses) the same as the penalty for 5,000 grams of cocaine powder (25,000 to 50,000 doses): a 10-year mandatory minimum.

The racially disproportionate impact of that arbitrary distinction was soon apparent. Crack offenders in the federal system were overwhelmingly black, while cocaine powder offenders were mostly white or Hispanic. In practice, race was strongly correlated with the sentences that cocaine offenders received: The darker a defendant’s skin, the more likely he was to be hit with a mandatory minimum, and sentencing guidelines were calibrated accordingly. Given two defendants who had committed essentially the same offense (measured by doses), the one with the paler complexion tended to receive a lighter punishment.

That realization, coupled with the collapse of the pseudoscientific rationales for treating crack and cocaine powder differently, eventually led to the Fair Sentencing Act of 2010, which Congress approved nearly unanimously and President Barack Obama signed into law. The Fair Sentencing Act replaced the 100-to-1 crack/powder ratio with an 18-to-1 ratio, which was still irrational but considerably less onerous. Yet the Fair Sentencing Act did not apply retroactively, meaning that thousands of crack offenders continued to serve prison terms that almost everyone agreed were too long.

In 2013, when Sens. Richard Durbin (D-Ill.) and Mike Lee (R-Utah) introduced a bill that would have applied the Fair Sentencing Act retroactively, Families Against Mandatory Minimums estimated that as many as 8,800 prisoners could benefit. By contrast, the FIRST STEP Act’s crack cocaine provision is expected to help a total of 2,600 prisoners. The difference largely reflects crack offenders who have already completed their excessively long sentences, along with some whose sentences were commuted by Obama.

As of April 30, the sentencing commission reports, 1,051 crack offenders had received sentence reductions under the FIRST STEP Act. More than 90 percent of them were black. On average, they were originally sentenced to nearly 20 years in federal prison. The average reduction was six years, meaning they will still end up serving an average of 14 years for “crimes” that involved the voluntary exchange of a psychoactive substance for money. While six extra years of freedom is nothing to sneeze at, putting someone in a cage for 14 years based on conduct that violated no one’s rights can hardly be described as just.

In short, it took Congress 24 years to address the disparity between crack and cocaine powder, then another eight years to take the obvious step of applying its recalibrated sense of justice to people who had already been sentenced. Sadly, a 30 percent sentence reduction for something that should not be treated as a crime to begin with counts as real progress in the United States, just as the Fair Sentencing Act’s more than fivefold reduction in the crazy crack/powder ratio counted as progress. But the progress is painfully slow and maddeningly incomplete for people languishing in prison and anyone who cares about them.