WASHINGTON (AP) — The number of federal drug prosecutions has dropped in the last year but the cases that are pursued involve more serious crimes, the Justice Department announced Monday in releasing new statistics across the agency.

Federal prosecutors also are charging drug criminals less frequently with crimes carrying rigid mandatory minimum punishments, Deputy Attorney General Sally Quillian Yates said in an interview with The Associated Press.

Fewer than half of all drug cases in fiscal year 2015 involved charges with a mandatory minimum sentence, in which punishments are closely tied to drug quantity, according to new data from the U.S. Sentencing Commission.

Justice Department officials say the new figures show that prosecutors are embracing the "Smart on Crime" initiative, which then-Attorney General Eric Holder announced in 2013 as a way to reduce spiraling prison costs and promote fairness in the criminal justice system.

The goal of that effort was to give prosecutors greater discretion in charging decisions and sentencing recommendations so that Justice Department resources and decades-long prison sentences could be reserved for major drug kingpins or more dangerous drug offenders — and not low-level criminals. Prosecutors were instructed to limit their use of mandatory minimum sentences and to steer clear of recommending them in cases of nonviolent drug offenders.

"The data that we're releasing reveals that Smart on Crime is more than just a paper policy," Yates said. "It's really a whole new approach to criminal justice."

Before implementation of Smart on Crime, Yates said, prosecutors were required to charge defendants with the maximum offense possible.

"There are some defendants that need the max, but what Smart on Crime does is it entrusts prosecutors to make charging decisions that take into account more than just drug quantity," while also encouraging judges to fashion more proportional punishments, Yates said.

The number of drug cases dropped by 6 percent from fiscal year 2014 to 2015, and by nearly 5,000 overall between 2012 and 2015, the data show. But the percentage of defendants who were armed and played leadership roles in the crime rose during that same period, which Yates says reveals a greater focus on more dangerous suspects.

The percentage of federal cases involving low-level offenders dropped.

Though some prosecutors had expressed concern that they'd lose leverage in plea negotiations without the threatened hammer of a mandatory minimum sentence, the Justice Department says drug defendants are still cooperating with the government, and pleading guilty, at the same rate as before.

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