Waterboarding: Charlie Don't Surf

Malcolm Nance, an advisor on terrorism to the US departments of Homeland Security, Special Operations and Intelligence, publicly denounced the practice. He revealed that waterboarding is used in training at the US Navy's Survival, Evasion, Resistance and Escape School in San Diego, and claimed to have witnessed and supervised "hundreds" of waterboarding exercises. Although these last only a few minutes and take place under medical supervision, he concluded that "waterboarding is a torture technique – period".

The practice involves strapping the person being interrogated on to a board as pints of water are forced into his lungs through a cloth covering his face while the victim's mouth is forced open. Its effect, according to Mr Nance, is a process of slow-motion suffocation.

Typically, a victim goes into hysterics on the board as water fills his lungs. "How much the victim is to drown," Mr Nance wrote in an article for the Small Wars Journal, "depends on the desired result and the obstinacy of the subject.

"A team doctor watches the quantity of water that is ingested and for the physiological signs which show when the drowning effect goes from painful psychological experience to horrific, suffocating punishment, to the final death spiral. For the uninitiated, it is horrifying to watch."