“a perfect storm of ignorance and enthusiasm,” a former C.I.A. official said.

The top officials he briefed did not learn that waterboarding had been prosecuted by the United States in war-crimes trials after World War II and was awell-documented favorite of despotic governments since the Spanish Inquisition; one waterboard used under Pol Pot was even on display at the genocide museum in Cambodia.

They did not know that some veteran trainers from the SERE program itself had warned in internal memorandums that, morality aside, the methods were ineffective. Nor were most of the officials aware that the former military psychologist who played a central role in persuading C.I.A. officials to use the harsh methods had never conducted a real interrogation, or that the Justice Department lawyer most responsible for declaring the methods legal had idiosyncratic ideas that even the Bush Justice Department would later renounce.