defence of consent in erotic-asphyxiation, either. Surely the real deterrent is the prospect of getting convicted of manslaughter if it all goes wrong.

The Americans are just as potty. An Iowa court decided in a case where a prostitute had been sexually tortured by her pimp that S&M was not a 'social activity' (so no photos of 'spanked out' debs in Tatler then) and therefore consent couldn't be a defence. Sportsmen kicking each other in the kidneys are protected but your suburban S&Mer isn't. These value judgements say more about the judges than what is or isn't safe and fun for consenting adults.

The line should be drawn closer to GBH ('really serious harm') than ABH ('any hurt calculated to interfere with the health or comfort of the victim'). I propose the 'matron test', which is that no one should be able to consent to anything that cannot be treated by a competent district nurse.

If the current law were consistently applied Max Mosley, like my friend, couldn't consent to his injuries. This is ludicrous. Just because

there is a defence in law doesn't mean it will be made out on the facts, and it's the facts that really matter. Consider Mosley's case: he played punishment games with willing participants, had sex - what's the point otherwise - and enjoyed a post-coital cup of tea. Nothing could be less evil or more civilised than that.