Manfred Nowak, the U.N. special rapporteur on torture, holds press conference... VIENNA (AP) - The U.S. is obligated by a United Nations convention to prosecute Bush administration lawyers who allegedly drafted policies that approved the use of harsh interrogation tactics against terrorism suspects, the U.N.'s top anti-torture envoy said Friday. Earlier this week, President Barack Obama left the door open to prosecuting Bush administration officials who devised the legal authority for gruesome terror-suspect interrogations. He had previously absolved CIA officers from prosecution.