It is worth noting that the methods in question were adopted from the training US soldiers undergo to resist interrogation. This underlines the fact that using these methods lowers the US to the level of its enemies. But it also suggests that distinctions may be made between waterboarding and, say, breaking on the rack. Unsurprisingly, US soldiers are not subjected to that technique as part of their training. Journalists and YouTube video-makers have undergone waterboarding, the better to pronounce it torture. None that I know of has volunteered to be flayed, or have his fingers crushed.
So far as moral and tactical justification goes, this can be set aside. Waterboarding is shameful, and one may leave it at that. To repeat, Mr Obama was right to forswear its use and that of other brutal measures. But the law does not set these points aside. If the lawyers who worked on the memos can show a court that they worked in good faith, under extreme pressure, to design methods that fell short of torture – in its legal, not commonsense, meaning – they would be innocent of knowingly shielding illegality. They have a strong case.
What would acquittals mean for US standing in the world? Those calling for prosecutions do not appear to have considered this possibility. They ought to.