The CIA’s use of “enhanced interrogation techniques” on terrorism suspects after the Sept. 11 attacks may have constituted a violation of the government’s rules against “human experimentation,” according to a report by the Guardian. A previously classified CIA document released Monday outlined the CIA director’s ability to “approve, modify or disapprove all proposals pertaining to human subject research,” despite the fact that such practices were prohibited without the subject’s consent.

“The CIA shall not sponsor, contract for, or conduct research on human subjects except in accordance with guidelines issued by the Department of Health and Human Services (HHS). The subject’s informed consent shall be documented as required by those guidelines,” the newly released, 41-page CIA document said, according to the Guardian.

The document was intended to establish guidelines for what officials could and could not do when interrogating suspects within the bounds of Executive Order 12333, a Reagan administration-era ruling that outlined the authority of America’s intelligence agencies. Despite its ban on human testing without subject consent, the document gave the CIA director the ability to alter related policies at his discretion.

Former CIA Director George Tenet, who served from 1996 to 2004, ordered in 2003 that medical officials oversee any use of “enhanced techniques” to interrogate suspects. Medical personnel were present at subsequent interrogations, such as the CIA’s first acknowledged use of waterboarding on detainee Abu Zubaydah. They purportedly provided CIA officials with information on how to use “enhanced interrogation techniques” on subjects, including which methods would be effective on which detainees, and how to revive incapacitated subjects so they could be interrogated further. Watchdogs interviewed by the Guardian said these practices, which occurred without consent, constituted human experimentation.

“CIA has had internal guidelines interpreting Executive Order 12333 in place continuously from 1987 to present. While some provisions in these guidelines have been amended since Sept. 11, 2001, none of those amendments changed provisions governing human experimentation or were made in response to the detention and interrogation program,” the CIA said in a statement in response to the Guardian’s report.

The document was made public six months after the release last December of the U.S. Senate Select Committee’s scathing report on the CIA’s torture practices. The report detailed how the agency used “enhanced interrogation techniques,” such as waterboarding, sleep deprivation and temperature manipulation,” to question suspects at sites around the world, the New York Times reported.