A newly declassified opinion in a Guantanamo prisoner lawsuit gives the most detailed picture yet of how U.S. authorities might overcome, to the satisfaction of civilian judges, allegations that torture taints key evidence.

U.S. District Judge Ellen Segal Huvelle's Aug. 3 ruling [PDF], unsealed yesterday, denies a Yemeni captive's bid to toss out confessions he claims were coerced.

The government has had few such victories in Guantanamo cases so far: Detainees have alleged coercion in 15 of 53 detainee lawsuits decided to date. The government has disproved their claims in at most three cases, ProPublica found in an examination co-published this week with the National Law Journal.

The ruling is the latest twist in detainee Sabry Mohammed Ebrahim al-Qurashi's effort to win release from the Cuban prison. He's been held there since May 2002, following his Feb. 7, 2002 arrest by Pakistani authorities. The Obama administration has accused him of being a member of al-Qaida. Its chief evidence, the judge said, consists of al-Qurashi's admissions to U.S. interrogators that he attended an al-Qaida training camp in Afghanistan.

Al-Qurashi now insists those admissions were not true. Abusive interrogators in Pakistan and Guantanamo told him what to say, he claims.

Huvelle said it was the government's burden to prove that al-Qurashi confessed voluntarily and, therefore, believably to a U.S. government agent in Karachi soon after his arrest.

In sworn filings, al-Qurashi described being brutally beaten by Pakistani interrogators, causing him to vomit blood and repeatedly pass out, hours before meeting with the U.S. agent. He offered statements from other Guantanamo inmates attesting to abusive treatment by Pakistani jailors.

But Huvelle was won over by the precision of the agent's testimony, given in person in her Washington, D.C., courtroom, and backed up by notes made at the time that al-Qurashi showed no signs of abuse. More than three pages describing his testimony are blacked out, but it's clear from the rest of Huvelle's opinion that she was impressed by the agent's recall of details, down to the tile floor of the interrogation room and the clothes he and al-Qurashi wore for their two-hour session.

The judge's ruling recounts the agent's medical and military experience, which began during Vietnam and included undergoing "abusive interrogations, simulated drowning, and overnight stress positions."

"This history makes it particularly likely that [Redacted] was able to accurately observe the physical and mental conditions of the arrestees whom he interviewed," Huvelle wrote, adding that the agent was a "credible and reliable witness."

Al-Qurashi was decidedly not, the judge concluded. He "changed his story" about abuse, adding greater detail, just after the government disclosed newly damning evidence, she said. She called his story "exaggerated."

Huvelle has yet to address the core challenge of al-Qurashi's lawsuit, known as a habeas petition, which is that he being wrongly held and should be released. His attorney, Michael Bhargava, did not immediately return a request for comment.

The government has lost 37 of the 53 Guantanamo habeas cases that have been decided, in most cases because it couldn't produce enough reliable evidence that the men were al-Qaida or Taliban militants. More than 50 such lawsuits are still pending in the federal court in Washington.