eric holder justice department
Washington CNN  — 

Federal prosecutors are bringing fewer prosecutions for illegal drugs and less often seeking mandatory minimum sentences, changes that Attorney General Eric Holder is hailing a major success of his tenure.

At the same time, the crimes being prosecuted carried higher minimum sentences on average because less-serious cases aren’t being pursued by federal prosecutors, according to Attorney General Eric Holder, citing data from the U.S. Sentencing Commission.

In a speech Thursday at the National Press Club, Holder pointed to the new data as showing the fruits of his Smart on Crime initiative, an effort focused on reducing federal sentences for non-violent drug crimes. Holder plans to leave office in the coming weeks, pending the Senate approval of U.S. Attorney Loretta Lynch.

Holder views the sentencing changes as a civil rights issue, because he and others argue that tough drug sentencing laws have a disproportionate impact on black and other minority defendants. The tough sentencing laws has also led to high incarceration rates and high prison costs, an issue drawing attention from both liberal and conservative political leaders.

“For years prior to this administration, federal prosecutors were not only encouraged – but required – to always seek the most severe prison sentence possible for all drug cases, no matter the relative risk they posed to public safety. I have made a break from that philosophy,” Holder said. “While old habits are hard to break, these numbers show that a dramatic shift is underway in the mindset of prosecutors handling nonviolent drug offenses. I believe we have taken steps to institutionalize this fairer, more practical approach such that it will endure for years to come.”

​A similar effort to soften mandatory sentences for non-violent drug crimes has gained bipartisan support in Congress, joining liberals like Sens. Dick Durbin and Patrick Leahy with libertarian-leaning conservatives such as Sens. Mike Lee and Ted Cruz. But those changes face an uphill climb with other law-and-order conservatives who hold leadership posts in the new Republican majority.

Sen. Charles Grassley, chairman of the Senate Judiciary Committee, recently took to the Senate floor to dispute what he says are myths about mandatory minimum sentences. He says the existing laws have been key to encouraging criminals to provide information to help prosecutors target bigger criminals.

“We are not sending huge numbers of nonviolent drug offenders to federal prison under lengthy mandatory minimum sentences.,” Grassley said. He criticized the bipartisan Senate proposal to change sentencing laws as possibly reducing sentences for terrorists who used drug trafficking to finance terror.

Holder, in his speech, cites the new data showing that prosecutors are pursuing mandatory minimums in just over 51% of drug cases in fiscal year 2014, down from nearly 64% of such cases in fiscal 2013.

The changes come amid reductions in prison populations and generally low crime rates, Holder said.

“This newly unveiled data shows we can confront over-incarceration at the same time that we continue to promote public safety,” Holder says in prepared remarks. “Already, in fiscal Year 2014, we saw the first reduction in the federal prison population in 32 years. Meanwhile, since President Obama took office, we’ve presided over a continued decline in the overall crime rate. This marks the first time that any Administration has achieved side-by-side reductions in both crime and incarceration in more than forty years.”

Obama commutes eight drug offenders’ sentences, why not others?