Only 12 US states are in full compliance with an prison anti-rape rule intended to keep juvenile offenders from adults.
Of the nation's 7,600-plus prisons, jails, community-based facilities and juvenile detention centres are being checked on their compliance with the law. According to the US justice department, 36 other states say they are working to comply.
Since 2012, states have been working to meet the standards set forth by the Prison Rape Elimination Act which was partially inspired by the 1996 death of Rodney Hulin, an undersized 17-year-old inmate who hanged himself in Texas after his requests for help following repeated rapes by adult inmates were denied.
Texas sheriff's offices say separating the two populations has been a challenge because of overcrowding and steep financial costs.
| The System - Juvenile Justice
"It's a big logistical headache," Brazos County Sheriff Chris Kirk said.
The law was also supposed to provide for better staff training, improved reporting and investigation of all sexual assaults behind bars and more money for research.
In 2011-12, an estimated 4 percent of state and federal inmates and 3.2 percent of jail inmates reported experiencing one or more incidents of sexual victimisation by another inmate or facility staff, according to the justice department.
The rape-prevention law "is a valuable and important act, and we take it very seriously," said Ryan Sullivan, a spokesman for the Harris County Sheriff's Office, which has about 150 youth offenders at its jail in Houston. The facility holds more than 9,000 inmates.
The Harris County Jail was cited in a May audit for not housing 17-year-old offenders apart from adult inmates. Elsewhere in Texas, Dallas County is spending more than $11,000 a week to keep at least 60 juveniles separated from adults at its jail complex.
Art Medina was imprisoned at 17 in Texas. He was later sentenced to life in prison in 1985 for his role in a fatal Houston-area carjacking and spent 15 years in solitary confinement after seriously wounding an inmate who threatened to rape him. He was paroled after serving a total of 26 years.
Now in his 40s, Medina has returned to the prison system as a volunteer to help adopt the PREA standards. He said in the past inmates felt like "nobody cares about them.
"That culture has changed. People are being held accountable," he said.
Charging juveniles as adults
The age separation has been especially complicated in states such as Texas which prosecute 17-year-olds as adults. Advocates say some facilities still question whether the federal mandate applies to them.
In many jurisdictions, one of the biggest barriers is summoning the political will to make changes, said Brenda Smith, who was a member of the National Prison Rape Elimination Commission, which helped develop the standards.
States that do not comply face losing 5 percent of their federal prison grants. County jails and local lockups are usually not included in the determination of whether a state is in compliance. Locally run facilities have no risk of losing federal money unless that funding is directly tied to a state contract for jail services.
Smith, a law professor at American University in Washington DC, said that means local authorities can be held accountable only by public criticism or lawsuits.
In Michigan, the prison system faces federal and state lawsuits filed by prisoners who allege that officials failed to adequately separate offenders aged 14 to 17 from adults, resulting in sexual assaults.
A Wisconsin legislative report concluded in July that the state's prison system was not splitting up the age groups. And an American Civil Liberties Union survey in North Carolina in 2014 found that none of the 60-plus county jails that responded appeared to be in complete compliance.
Those findings have renewed calls for the states that prosecute 17-year-olds as adults to raise their age of adult criminal responsibility to 18. Those states include Texas, Michigan and North Carolina. Sullivan, Kirk and other Texas jail officials say they would be in favour of raising the age.
Efforts to raise the age failed in the last legislative session in Texas, but advocates plan to try again next year, said Elizabeth Henneke, policy lawyer with the Texas Criminal Justice Coalition.