A 13-page letter delivered to Defense Secretary Chuck Hagel cites worsening conditions and leadership failures comparable to those that led to the My Lai massacre in Vietnam, The Miami Herald reported Tuesday.
The letter says death among the inmates is "imminent ... whether by suicide, starvation, organ failure or associated complications."
It calls for "active engagement, encouragement and leadership" to ensure the prisoners' humane treatment.
The letter is signed by military lawyers for eight of the 15 prisoners formerly held captive by the CIA.
"Just as the events leading to the massacre at My Lai derived from the dehumanization of the Vietnamese," the lawyers said, "there should be no question that the root of war crimes and mistreatment of prisoners likewise requires one human being to dehumanize another."
The letter charges the prisoners have been subjected to a "systematic pattern" of harassment and degradation that has eroded the attorney-client relationship.
The attorneys asked Hagel to examine the "fitness to command" of Army Col. John Bogdan, the commander of the prison. They say Bogdan was in charge when an eavesdropping system was discovered in attorney-client meeting rooms.
They also accused him of a "heavy handed response" to an ongoing prisoner hunger strike.