First you should look at the CIA's policy on human experimentation (which is still in effect).
you can read that here.
Then go on to read the whole article at the Guardian, here.
"After reviewing the document, one watchdog said the timeline suggested the CIA manipulated basic definitions of human experimentation to ensure the torture program proceeded.
“Crime one was torture. The second crime was research without consent in order to say it wasn’t torture,” said Nathaniel Raymond, a former war-crimes investigator with Physicians for Human Rights and now a researcher with Harvard University’s Humanitarian Initiative."