A federal judge Wednesday refused to lower the prison terms of two top associates of one of Washington’s most notorious drug gang leaders, making Melvin D. Butler and James Antonio Jones the first of nearly 50 offenders in the District to be denied under a new effort to reduce sentences in some drug cases.

Although federal prosecutors did not oppose a defense request to have the men released from prison in November, U.S. District Judge Royce C. Lamberth declined to cut about two years from each man’s projected 28 1/2 -year sentence.

In doing so, the judge rebuked the office of acting U.S. attorney Vincent H. Cohen Jr. of the District, saying prosecutors did not give due weight to the criminal histories of Butler, 52, the Los Angeles-based cocaine broker and partner of D.C. drug lord Rayful Edmond III, and Jones, 58, one of four top armed “enforcers” of Edmond’s violent trafficking network. The group imported as much as 1,700 pounds of Colombian cocaine a month into the city in the 1980s, according to court papers.

Edmond’s organization enabled drug addiction on a scale that until then “was unprecedented and largely unimaginable” in Washington, Lamberth wrote, and the harm the defendants caused “is immeasurable and in many cases irreversible.”

“To put it bluntly, the court is surprised and disappointed by the United States attorney’s decision to not oppose the present motions,” Lamberth said. “The court struggles to understand how the government could condone the release of Butler and Jones, each convicted of high-level, sophisticated and violent drug-trafficking offenses.”

Bill Miller, a spokesman for the U.S. attorney’s office, said it is reviewing the decision and had no comment.

Assistant Federal Public Defender Dani Jahn said that both men would face less time if sentenced under current law, that they had exhibited model behavior while serving more than 26 years in prison and that they will be eligible for release within 28 months.

“These men are not the same men that were imprisoned in 1989,” Jahn said.

Defense attorneys for Butler and Jones sought relief after a 2014 U.S. Sentencing Commission decision that allowed nearly 46,000 of about 100,000 federal drug offenders now in prison to seek reduced sentences, subject to court approval.

The resentencing initiative excludes career or armed career criminals, among others, and came after the commission lessened punishments for most future drug offenders.

Butler and Jones became the first of 47 offenders in the District whose unopposed requests were denied by a federal judge. About 100 cases remain in process in the city.

Nationwide, judges have granted retroactive requests in about 76 percent of 17,446 cases so far, according to the commission. None have been released, with the first set to go free Nov. 1.

The changes come as the Obama administration and Congress have discussed further sentencing reform initiatives aimed at reducing punishments for nonviolent drug criminals. The move is driven by spiraling prison costs and inmate populations, plummeting crime rates and mounting controversy over the social costs of exceptionally high rates of incarceration in the United States.

In his decision, Lamberth, a Reagan appointee and district chief judge from 2008 to 2013, said redress is appropriate for many inmates sentenced unfairly or disproportionately for drug-related crimes or subjected to unduly harsh mandatory minimum federal prison sentences, including those who faced enhanced penalties for gun use.

But Lamberth quoted a June 2014 statement expressing the Justice Department’s views before the Sentencing Commission in which Sally Yates, then U.S. attorney for the Northern District of Georgia and now deputy U.S. attorney general, said, “We believe that retroactivity in the drug amendment should be limited to lower-level, non-violent drug offenders without significant criminal histories.”

Butler was arrested April 28, 1989, convicted at trial and sentenced to life in prison, reduced to 34 years on appeal. With good time credits, he is projected for release in October 2017. Jones was sentenced to 30 years and is projected for release in February 2018.

A former Los Angeles gang member, Butler met Edmond in Las Vegas after a championship boxing match, linking the latter to Los Angeles organizations with Cali cartel connections in Colombia.

At his arrest in 1989 at age 24, Edmond was reported to have introduced crack cocaine to the District, controlled 20 percent of the city’s cocaine trade and booked up to $1 million in profits a week. His network’s enforcers were linked to 30 killings.

Edmond remains in prison.