Former U.S. Attorney Eric Holder urged a overhaul on drug sentencing laws on Nov. 5 and said that "the system as we know it cannot be economically sustained". (McKenna Ewen and Victoria M. Walker/The Washington Post)

Former U.S. Attorney General Eric H. Holder Jr. on Thursday urged Congress not to let slip away “a historic opportunity” to overhaul federal drug sentencing laws and said lawmakers should consider further changes in House and Senate talks if pending legislation is approved.

In a rare public address since stepping down in April, Holder also defended the Obama administration’s effort during his six years as head of the Justice Department to reduce racial disparities in law enforcement and reverse an explosion in prison populations and costs. “The system as we know it,” he said, “cannot be economically sustained.”

“This presents, I believe, a historic opportunity to improve the fairness and the efficiency of our criminal justice system,” Holder said during a speech before federal judges in Washington.

Former attorney general Eric Holder delivers the seventh-annual Judge Thomas Flannery Lecture on Nov. 05, 2015, in Washington. (Bill O'Leary/The Washington Post)

“But unless we act quickly — and unless we act expansively — we risk letting this moment pass,” Holder said, adding, “More needs to done.”

Among a list of recommendations, Holder called for added funding within five years to pay for federal drug courts in every U.S. district to provide alternatives to incarceration. He called for the elimination of sentencing disparities that still penalize crack more harshly than cocaine and for increased spending on reentry programs for ex-offenders.

Holder also continued a divisive debate within the Obama administration over statements by FBI Director James B. Comey last month that suggested that heightened scrutiny of police might be making some police less assertive in their work and be leading to rising crime in some cities.

That point was echoed Wednesday by Chuck Rosenberg, the acting chief of the U.S. Drug Enforcement Administration and Comey’s former chief of staff.

While not referring to either former colleague or their claims of a “Ferguson effect” — a reference to the Missouri city torn by protests last year after a fatal police shooting of a black youth — Holder said changes he championed have made the legal system “more fair and more effective,” aligning himself with Obama and White House officials.

“Reform has not made us less safe — this is simply a fact. Contentions to the contrary I believe are based on outdated ideology or simple fear of change,” Holder said. “To the extent that we have seen a rise in crime in some places this calendar year, it is not as a result of reform efforts.”

As attorney general, Holder was a prominent backer of shifting the nation’s approach to incarceration and drug sentencing policies, a change fueled by bipartisan agreement that a sevenfold increase in U.S. prison populations since the 1980s has driven prison costs to unsupportable levels while having a devastating impact on black and Latino communities that has done more harm than good to society.

Holder helped initiate a reduction in the 100-to-1 sentencing disparity between crack and powder cocaine offenses to 18-to-1 and led a “Smart on Crime” initiative that directed federal prosecutors in low-level drug cases to avoid triggering mandatory minimum sentences as a way of reserving the harshest penalties for the most serious offenders.

Federal authorities at his urging also reduced federal sentencing guidelines for certain current and past drug offenders, and the Justice Department supported prison reentry and diversion programs.

On Thursday, Holder noted the advancement of bills in Congress and listed additional goals that he hoped might emerge.

Among those, Holder called for an across-the-board reduction in the number of crimes subject to mandatory minimum sentences and the length of those sentences, and an increase in credits that allow federal inmates to reduce their time served through good conduct while imprisoned.

Holder spoke at the U.S. district courthouse in Washington, where he delivered the seventh-annual Judge Thomas A. Flannery Lecture, named after the judge who served 36 years on the bench before his death in 2007. The address has become a platform over the years for senior federal officials, Supreme Court justices, judges and others connected with the court to address an influential audience blocks from the U.S. Capitol.

Before serving as deputy attorney general in the latter half of the Clinton administration and becoming attorney general in 2001, Holder served nearly a decade as a D.C. Superior Court judge and as the first African American U.S. attorney for the District, as well as the first top federal prosecutor recommended by the city’s non-voting representative to Congress.

Holder has spoken often of how his views on sentencing were shaped by his time as a front-line judge and prosecutor as Washington and its majority-black population suffered through the crack epidemic that made the city in the 1980s and 1990s among the nation’s most violent.