Lawyers for a Guantanamo Bay inmate who was subjected to brutal treatment at CIA “black sites” can question two U.S. psychologists who designed the government’s interrogation program, a federal appeals court said Wednesday in a ruling that took the rare step of disdaining the euphemism “enhanced interrogation techniques.”

“To use colloquial terms,” said the Ninth U.S. Court of Appeals in San Francisco, “Abu Zubaydah was tortured.”

Zubaydah was wounded and captured in Pakistan in 2002 by U.S. agents, who labeled him a high-ranking Al Qaeda operative. He was shuttled between secret CIA sites for the next four years before winding up at Guantanamo, where he is being held as an “enemy combatant,” not charged with any crime.

The court case involves efforts by the government of Poland, where Zubaydah was held from December 2002 to September 2003, to identify and possibly prosecute Polish citizens and government officials who took part in his interrogation.

Although the appeals court said Zubaydah’s lawyers could question American psychologists James Mitchell and Bruce Jessen, it’s not clear how much of the information, if any, will be turned over to Polish prosecutors. The 2-1 ruling said only that a federal judge had gone too far in concluding that any such questioning would expose state secrets about CIA detention and interrogation practices, and must take a closer look to determine which subjects could be safely examined.

But Joseph Margulies, a Cornell University law professor who represented Zubaydah for more than a decade, said the ruling was still a milestone.

“It’s the first time an appellate court, to my knowledge, has come right out and said that the enhanced interrogation techniques were torture,” he said. “We’re no longer going to equivocate.”

In addition, he said, “it’s the first time a court has acknowledged that the government was simply mistaken about Abu Zubaydah, the poster child for the torture program.”

The court cited a report in 2014 by the Senate Select Committee on Intelligence, chaired by Sen. Dianne Feinstein, D-Calif. Most of the 6,700-page report remains classified, but a 525-page public summary included a disclosure that the CIA had eventually concluded Zubaydah was not a member of Al Qaeda. The report also found that torture in interrogations had produced little useful intelligence.

At the secret CIA sites, the court said, Zubaydah was “persistently and repeatedly waterboarded,” held in a “coffin-sized ... confinement box” for hundreds of hours, kept in cramped and stressful positions, slapped, grabbed and deprived of sleep. Insects were placed near him to exploit a personal phobia, and he was subjected to a mock burial.

His lawyers say Zubaydah suffered permanent brain damage, multiple seizures and the loss of vision in his left eye. The European Court on Human Rights found Poland complicit in Zubaydah’s torture in 2015 and ordered the Polish government to pay him $147,000.

Mitchell and Jessen, psychologists in Spokane, Wash., were hired by the CIA as independent contractors, developed the interrogation program, and, according to the Senate report, took part in waterboarding Zubaydah. Two other torture victims, and the estate of a third man who had died, reached a confidential settlement with the psychologists in 2017 after a federal judge refused to dismiss their lawsuit.

In seeking to prevent Zubaydah’s lawyers from questioning Mitchell and Jessen, the U.S. Justice Department argued that the answers could reveal classified information about CIA intelligence sources, foreign government cooperation and terrorist investigations. But the appeals court said some information about the CIA’s torture program and its past operation in Poland has long been known to the public.

The purpose of confidentiality rules “is to protect legitimate government interests, not to shield the government from uncomfortable facts,” Judge Richard Paez said in the majority opinion. He said the federal judge in charge of the case should be able to “disentangle the privileged from nonprivileged information” when the psychologists are questioned.

His opinion was joined by U.S. District Judge Dean Pregerson of Los Angeles, temporarily assigned to the appeals court. Judge Ronald Gould dissented, saying the questioning of Mitchell and Jessen “jeopardizes critical national security concerns” and that there was no need for the court to decide whether Zubaydah had been tortured.

Bob Egelko is a San Francisco Chronicle staff writer. Email: begelko@sfchronicle.com Twitter: @BobEgelko