NAZI hunter Simon Wiesenthal was often asked why he pursued old men about events from so long ago. He replied: "I am someone who seeks justice, not revenge. My work is a warning to the murderers of tomorrow that they will never rest."

Those words highlight everything wrong about US President Barack Obama's response to the so-called "torture memos". The documents, written by lawyers in George Bush's Justice Department, authorise CIA interrogation techniques. They permit agents to push prisoners into walls, slap them on the face and abdomen, douse them in very cold water, strip them naked, house them in dark, cramped spaces, force them into painful positions (one memo reads, "in wall standing, all of the individual's body weight is placed on his fingertips") and deprive them of sleep for up to 180 hours (while shackled and in nappies).

And they authorise water-boarding. Known in the Spanish inquisition as toca, or tortura del agua, water-boarding — which induces the physiological responses associated with drowning — was used by Marcos in the Philippines, Pinochet in Chile and Pol Pot in Cambodia. The new memos show that the CIA performed water-boarding on Khalid Sheikh Mohammad 183 times in a month, and on Abu Zubaydah, who seems to have been mentally ill, 83 times. CIA doctors stood by to perform an emergency tracheotomy — a wise precaution, since one memo suggests a detainee (probably Abu Zubaydah) stopped breathing or lost consciousness.

To his credit, Obama has publicly acknowledged the obvious: water-boarding is torture. Yet he has made it clear that interrogators will face no sanctions, saying: "I do not think it's appropriate for them to be prosecuted."

But low-ranking individuals ordered to carry out torture invariably do so within guidelines provided by their superiors. Here is part of the charge sheet drawn up by American lawyers against a civilian employee of the Imperial Japanese Army: "In or about August 1943, the accused, Genji Mineno, together with other persons did, willfully and unlawfully, brutally mistreat and torture George De Witt Stoddard and William O. Cash, American prisoners of war, by strapping them to a stretcher and pouring water down their nostrils." Mineno was sentenced to 20 years' hard labour — even though official Japanese army manuals instructed interrogators to torture POWs.