President Obama tours El Reno Federal Correctional Institution in El Reno, Oklahoma. Obama is calling for prison reform, including an examination of the use of solitary confinement. Advocates in Maryland are pushing for more data on prisoner isolation in their state. (Saul Loeb/AFP/Getty Images)

The isolation cells were about the size of a walk-in closet, freezing cold in winter and sweltering in summer. Locked inside for 23 hours a day, some prisoners shouted through the door constantly, desperate to hear an answering voice.

“Where you’re the only one in the cell,” said Shola Oloyede, who was released from a Maryland prison Thursday after spending nearly a third of his nine-year sentence in isolation, “that right there drives you crazy.”

Advocates have pressed for years to reduce the practice of isolating prisoners, citing enormous psychological and fiscal costs. Their call increasingly is being heard by both Democratic and Republican politicians.

States such as Virginia have begun to examine their use of solitary confinement, and President Obama last week visited a federal penitentiary and announced a set of prison-reform efforts that includes a review of isolation policies and practices.

President Obama, photographed through a prison cell window. (Kevin Lamarque/Reuters)

Locking people away “in tiny cells for 23 hours a day, sometimes for months or even years at a time . . . is not going to make us safer,” Obama said. “Our prisons should be a place where we can train people for skills that can help them find a job, not train them to become more-hardened criminals.”

But in Maryland, where Oloyede served time for armed robbery, advocates are stumbling in the dark. They don’t have solid information on how often prisoners are isolated, and bills that would require the prison system to report such data have gone nowhere in the General Assembly.

A report commissioned in 2012 by a nonprofit organization suggests that Maryland isolates more prisoners than other states — 8.5 percent compared with 5 percent in Virginia. Advocates are pushing for more information and say they will try again next year to pass a reporting law, despite opposition from prison administrators and legislators.

“It’s hard to measure any progress or measure the status of something without the data,” said Susan Kerin of Interfaith Action for Human Rights, which has lobbied the state’s Department of Public Safety and Correctional Services for more information. “Especially in this society, data is everything.”

Advocates say at least 44 states and the federal prison system use some form of solitary confinement or segregation, a figure based on the number of states that have special “supermax” prisons, where the entire population can be held in isolation cells.

Colorado, Maine and Texas have passed transparency bills to release numbers about segregation. But most states are not required to report such information.

The most recent national estimate — which suggests about 80,000 prisoners in solitary confinement — comes from a 2005 Bureau of Justice Statistics census report.

In a 2012 letter to the Baltimore Sun, the head of Maryland’s corrections department said that the state did not use solitary confinement but that it segregates prisoners when necessary.

Then-corrections secretary Gary D. Maynard wrote that the system’s “segregation” policy tried to limit the time that prisoners spend in isolation units, prohibited putting mentally ill inmates in segregation and used “double-celling,” placing two prisoners in one cell, rather than solitary confinement. (Advocates say double-celling still isolates inmates for up to 23 hours a day and has effects similar to solitary confinement.)

But the report the department commissioned that same year from the Vera Institute of Justice documented multiple segregation sentences that exceeded stated maximums and cited a “lack of mental health and special needs interventions.”

The report made 10 recommendations, including improving training and decreasing the number of mentally ill patients in segregation.

Advocates say there is no evidence that any of the recommendations have been implemented.

They also say the lack of data on who is kept in isolation stems in part from how prison systems are organized.

“It’s easy to believe or assume that there is some effort to hide what’s going on,” said Christine Herrman of the Vera Institute of Justice. But prison systems, which track inmates by disparate factors such as location or disciplinary record, “weren’t built to answer those questions.

Gerard Shields, a corrections department spokesman, said Maryland does not track the number of prisoners kept in segregation at its 24 facilities.

The department’s special-needs units “employ a strong team therapeutic approach to dealing with segregation inmates who have mental health issues,” Shields wrote in an e-mail. He said the department hopes to implement new “restricted housing” that would limit the need for isolation.

“Reducing the use of segregation is a significant goal that the Department is working toward right now,” Shields wrote. “It’s a priority within all of our correctional divisions.”

Advocacy groups, including ACLU Maryland and the Maryland Alliance for Justice Reform, pushed for legislation in 2014 and this year that would require annual reports on segregation. This year’s bill would have required data on inmate demographics, confinement conditions and costs.

Both bills died in committee, after the corrections department said implementing them would be costly and told lawmakers that a review by the National Institute of Corrections was being conducted instead.

“If you aren’t even willing to agree to transparency, that’s a huge red flag,” said Amy Fettig, senior staff counsel at the national ACLU.

Kerin, of the Interfaith Action group, said the bills did not have the support of leading Democratic lawmakers. “If leadership doesn’t want it, nobody votes for it,” she said.

But some legislators said the decision to reject the bill was more nuanced. Del. Kathleen M. Dumais (D-Montgomery), vice-chair of the Judiciary Committee, cited statements by corrections officials that some mentally ill prisoners are safer when secluded from other inmates.

“We have to give the individuals who are in corrections the ability to be flexible and listen to those who are treating some of these individuals,” Dumais said.

Advocates say it’s not enough to trust that reforms will be made on their own. “In Annapolis, when an agency or administration chooses not to do something, they usually say, ‘we don’t need legislation because we’re going to implement some corrective measures anyway,’ ” said Del. Jill P. Carter ­(D-Baltimore), who sponsored the 2015 bill and was the only member of the Judiciary Committee to vote for it. “But you need the legislation to make sure it’s done.”

Sen. Robert A. Zirkin ­(D-Baltimore County), chairman of the Judicial Proceedings Committee, sent a letter to the corrections department last month informally requesting more information about segregation. The deadline, which Shields said the agency will honor, is Oct. 1.

In the meantime, advocates say they will work to build a stronger coalition to oppose prisoner isolation in advance of next year’s legislative session.

Oloyede, who was released from prison Thursday, has simpler goals. The 33-year-old said he is hoping to start over in an unfamiliar world.

“I was looking for a pay phone and someone said, ‘Pay phone? Nobody uses pay phones anymore,’ ” he said.

He is trying to adjust psychologically as well. After coming out from segregation, “you really don’t want to be around people,” he said. “You’re really jumpy because you’ve been confined for that long.”