Nearly 1,900 federal prisoners are estimated to be eligible for immediate release as new sentencing guidelines for crack cocaine are applied retroactively starting today, The Associated Press reports.

Until last year, prison sentences for people convicted of crack cocaine possession were significantly harsher than for people caught with powdered cocaine.

According to the AP:

Under a law passed in the 1980s, a person convicted of crack possession got the same mandatory prison term as someone with 100 times the amount of powdered cocaine. Five grams of crack, about the weight of five packets of Sweet N'Low, brought a mandatory five years behind bars; it took 500 grams of powdered cocaine to get the same sentence.

Reuters reports that more than 80 percent of those jailed for federal crack convictions over the past 25 years have been African Americans, according to NAACP statistics.

Congress reduced the disparity in prison sentences for future cases with 2010’s Fair Sentencing Act, and this summer the U.S. Sentencing Commission, which sets federal sentencing policy, said it would also apply the act to inmates already in prison, Reuters reports.

Inmates will get an average of three years taken off their sentences, with early releases largely spread out over the next several years, the AP reports. In all, about 12,000 prisoners are expected to benefit from the rule change.

The U.S. Sentencing Commission said the retroactive application of the rules could result in savings of more than $200 million in the first five years after it takes effect, Reuters reports.

Jim Wade, the federal public defender in Harrisburg, Pa., told the Allentown Morning Call that the new sentencing guidelines are a godsend for his clients, many of whom were not career criminals or large-scale dealers. “It's going to mean a lot to folks who are in prison and to their families,” Wade said. “It's a chance to restart and grow from a mistake. That's what we all hope.”

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