During the Bush administration, the Justice Department issued secret memos blessing the so-called enhanced interrogation techniques as lawful despite anti-torture laws. The C.I.A.’s inspector general and the Senate Intelligence Committee later found that the agency inflicted more severe abuses on captives than it had told the Justice Department or its overseers. The department declined to prosecute anyone for his or her involvement in the program.
In a statement after the rulings, Amrit Singh, a lead lawyer for the matter for the Open Society Justice Initiative, which filed a complaint with the court on behalf of Mr. Nashiri, said that the justice system’s acknowledgment of what happened was important.
“The European court’s ruling is critical for upholding standards of international law — including that torture is absolutely prohibited,” she said. “It stands in stark contrast to the United States’ decision to promote Gina Haspel to C.I.A. director despite her role in my client’s torture.”
The C.I.A. declined to comment.
Abu Zubaydah was captured in Pakistan in March 2002, and later held in Thailand, Poland and Lithuania. He was initially considered a Qaeda leader involved in planning terrorist attacks. But the Senate Intelligence Committee report found that C.I.A. records did not support those claims, and the agency later concluded that while he was involved in jihadist training camps, he was not a member of Al Qaeda.
Mr. Nashiri was captured in Dubai in October 2002 and was held in Romania between 2004 and 2005, the court said. He is accused of helping orchestrate an attack in 2000 on a United States Navy destroyer, the Cole, in the harbor of the Yemeni port of Aden, which killed 17 sailors, and an attack on a French oil tanker, the Limburg, in 2002.
On Thursday, in separate rulings issued simultaneously, the court said that Lithuania and Romania knew enough that hosting the C.I.A. prisons — and failing to adequately investigate what happened inside them — violated their obligations under the European Convention on Human Rights.