Holder on Monday called for a special counsel to review CIA interrogation practices in a "preliminary" criminal investigation to determine if intelligence officers violated U.S. laws concerning the treatment of detainees.
The CIA through heavily-censored documents provided details of some abusive behavior used against high-profile detainees, including mock executions and threats of severe physical harm.
Navi Pillay, the human rights commissioner, said she welcomed the move, adding her support for further steps to hold anyone who violated the law accountable.
"I warmly welcome this responsible decision by the U.S. government to open a preliminary investigation," she said.
She went on to say there should be no "impunity for torture" whether it was conducted on U.S. territory or anywhere else in the world.
Pillay described the use of so-called black sites to secretly house terrorist suspects as inappropriate and harmful.
"Secrecy has been a major part of the problem with this type of detention regime," she said. "When guards and interrogators think they are safe from outside scrutiny, and legal safeguards are circumvented, laws become all too easy to ignore."