A massive influx of applications from prisoners and a complicated review process have slowed the Obama administration’s highly touted initiative to grant clemency to nonviolent offenders, shifting the burden to an army of pro bono lawyers and specialists willing to help.

Just over a year after the administration unveiled its initiative, President Obama has commuted the sentences of eight prisoners, all of whose applications had already been submitted at the time of the announcement. In the meantime, more than 35,000 inmates — about 16 percent of the federal prison population — have applied to have their sentences shortened under the Justice Department-led initiative.

In an unusual arrangement, the department has sought to deal with the deluge by encouraging outside lawyers to help identify candidates for earlier release and to represent them. Prisoner applications are being reviewed by more than 1,000 attorneys at 323 law firms and organizations nationwide.

“We have created what very well may be the largest, most ambitious pro-bono effort in the history of the legal profession,” said Norman L. Reimer, executive director of the National Association of Criminal Defense Lawyers, one of the four groups that make up what is known as the Clemency Project 2014.

Reimer, detailing the group’s efforts for the first time, said it spent all of 2014 “gearing up” and was hopeful the process would be accelerated soon.

Graphic: Here’s what America’s federal prison inmate population looks like

Justice officials say the clemency initiative is part of their effort to address drug sentences they believe were too harsh.

In 2010, Obama signed the Fair Sentencing Act, which eliminated the five-year mandatory minimum sentence for the simple possession of crack cocaine and reduced the disparity between convictions for crack and powder cocaine. But thousands of inmates are still serving federally mandated sentences under the old sentencing guidelines.

The initiative is also aimed at reducing the nation’s federal prison population, which has ballooned to about 210,000 inmates, costing taxpayers $6.5 billion annually, about 25 percent of the Justice Department’s discretionary budget. Officials said those costs are eating into efforts to curtail violent crime, drug cartels, public corruption, financial fraud and human trafficking.

“If we don’t find a solution to the federal prison population problem, public safety is going to suffer,” James M. Cole, then deputy attorney general, said in announcing the initiative in January last year.

Candidates for clemency under the new Justice Department criteria, released in the spring, must have served at least 10 years of their sentence, have no significant criminal history and no connection to gangs, cartels or organized crime. Applicants also must be inmates who probably would have received a “substantially lower sentence” if convicted of the same offense today.

Even given those criteria, however, the universe of inmates who might qualify is huge, lawyers say.

“We had decades of harsh sentencing,” said Marjorie J. Peerce, a partner at Ballard Spahr in New York, whose lawyers have been screening clemency applications. “People were going to jail for decades because they were drug addicts selling a little bit of crack. There was such a disparity, and it was disproportionately affecting minorities.”

In December, Obama cut short the sentences of eight federal low-level cocaine or methamphetamine offenders, four of whom were serving life in prison. Since then, the Clemency Project — which includes Families Against Mandatory Minimums, the American Civil Liberties Union, the American Bar Association and Reimer’s association of criminal defense attorneys — has sent the petitions of only 14 inmates to the Justice Department’s Office of the Pardon Attorney to be considered for clemency.

The progress of the overall effort has proven deeply frustrating to prisoners’ advocates.

Mark Osler, a law professor at the University of St. Thomas in Minnesota and an advocate for inmates petitioning for clemency, said there are “thousands” of inmates just as worthy of clemency as the eight who were granted it by the president at the end of last year.

“The injustice will be if this administration ends with them in prison,” he said. “This is one of the major justice issues of our time.”

Lawyers with the Clemency Project say the pace is partly a symptom of dealing with clients whose cases are complex and whose ability to communicate is limited because they’re incarcerated. Every lawyer participating in the project had to be trained to sift through the applications to identify candidates who met the Justice Department criteria. In many cases, they had to try to locate old legal documents and contact prosecutors and judges who imposed the sentences for answers.

Most of the inmates who requested assistance from the lawyers sent applications electronically through the Bureau of Prisons computers, but several thousand who didn’t have access to computers sent paper applications that had to be manually entered into an enormous database the attorneys have built. Prisoner applications are still trickling in.

“Some of these inmates have been in 20 to 25 years. Lawyers have to try to get pre-sentencing reports and sentencing transcripts, and, in some cases, the sentencing proceeding might not have been transcribed. It’s a cumbersome process, and you want to get it right,” Peerce said.

Although the Clemency Project is facilitating the process for inmates, it is not working directly with the Justice Department.

Inmates can contact the Clemency Project, which will research and prepare petitions for qualified candidates and send them to the Office of the Pardon Attorney, or, as 5,333 inmates have done since the spring, apply directly to that office. From there, petitions with recommendations go to the office of acting Deputy Attorney General Sally Quillian Yates.

Yates then sends the petitions with her recommendations to the White House counsel, Neil Eggleston, who sends them with his recommendations to Obama.

Some advocates view that process as overly cumbersome. Justice Department spokeswoman Emily Pierce said that the agency “remains committed to the President’s Clemency Initiative, consistent with our overall efforts to modernize outdated sentencing laws.”

“The Clemency Initiative is just one prong of the tools we are using to accomplish that goal, including pushing sentencing reform in Congress and through the Sentencing Commission,” Pierce said. “We also are committed to ensuring that each individual who applies is treated fairly and equally and that public safety is a consideration in each and every petition under consideration.”

Reimer, of the National Association of Criminal Defense Lawyers, said that now that the Clemency Project has put in place a process for sorting out clemency applications, it plans to review and submit them to the Justice Department more quickly.

“We’ve got a lot of work this year, but we’re determined to do it,” he said. “We will find everyone who may qualify and complete that by sometime early next year.”