Here we go again:  three Congressmen asked the General Accounting Office to determine what is going on with the isolated segregation units throughout the federal Bureau of Prisons.  Turns out the BOP doesn’t even know:  “The U.S. Bureau of Prisons currently holds more than 12,400 individuals in 23-hour-a-day lockdown, making it the largest practitioner of solitary and other forms of isolated confinement in the nation, and most likely the world. Yet the BOP does not know whether its use of “segregated housing” has any impact on prison safety, how it affects the prisoners who endure it, or how much it all costs American taxpayers.”

http://solitarywatch.com/2013/06/01/gao-report-questions-widespread-use-of-solitary-confinement-in-federal-prisons/