Ibrahim Idris is an obese, diabetic, schizophrenic Sudanese man who has mostly lived at Guantánamo’s psychiatric ward since he got to the U.S. terror prison in Cuba on the day it opened.

U.S. military intelligence has profiled him as an al-Qaida insider. But even his fellow prisoners don’t want him around, according to court records, because he behaves bizarrely — wears his underwear on his head, whispers to himself, is delusional.

Now his New York lawyers are arguing a novel twist in a war-on-terror habeas corpus petition at the U.S. District Court in Washington, D.C. Rather than ask Chief Judge Royce Lamberth to judge what Idris did or did not do before he got to Guantánamo, they argue he’s too fat, too crazy and too physically sick to be a danger in the future. So Lamberth should send him home.

The 14-page petition, backed by medical reports from the prison, does not even address U.S. military claims that Idris was captured in the company of other al-Qaida combatants, that he probably was at Tora Bora after the Sept. 11 attacks.

Instead, the brief invokes U.S. Army regulations that recommend repatriation of POWs who are so sick they can’t recover. Plus, they note, the Geneva Conventions require a war prisoner be sent home if his mental or physical fitness “have been gravely diminished.”

Jennifer Cowan, who has been Idris’ court-appointed lawyer since 2005, explains it this way: “If you’re so sick that you can’t return to the battlefield, there’s no basis for holding you.”

Idris, she notes, “has multiple illnesses. He has mental illnesses, which are severe, physical illness that’s long-standing, and nobody thinks he’s going to recover from any of those. It’s not like he has a cold.”

For its part, the Defense Department won’t comment on the case because it’s in litigation, says Army Lt. Col. Todd Breasseale. Government lawyers have until July 15 to respond.

The suit was filed the same day the U.S. Southern Command released a report that found Guantánamo guards and medics broke their own medication and observation rules in the September suicide by a Yemeni captive named Adnan Latif. The military said Latif, also a frequent resident of the prison’s psych ward, overdosed on hoarded anti-psychotic drugs a day after he was put into a disciplinary cell. Unlike Latif, Idris has refused psychiatric medications for years and, according to his attorney, has not had discipline problems.

Idris, who is in his 50s, stood five feet seven inches and weighed 206 pounds at Guantánamo on Jan. 12, 2002, prison camp court records say. A day earlier, a Navy petty officer photographed the first 20 captives to arrive at Camp X-Ray inside a cage of chain-link fence, shacked and on their knees. Since then, Idris has packed on at least 50 more pounds and hasn’t stopped eating, according to his lawyers, even amid a widespread hunger strike at Guantánamo that has grabbed the headlines.

In 2009, an Army psychiatrist whose name is expunged from the court record, diagnosed Idris as suffering from “schizophrenia, disorganized type.” The doctor, an Army lieutenant colonel, advised the federal court in Washington that Idris was so mentally ill he couldn’t work with his lawyers, so delusional he couldn’t separate his life at the prison from “his internal fantasy world.” And the doctor advised the court that the Sudanese captive was diagnosed as having a mental illness within weeks of getting to Guantánamo.