"if there is some blood alcohol level after which informed consent no longer applies?"According to an informal view of identity, there is some blood alcohol level at which you are no longer the same person. Can a sober person repudiate the past or future actions of his drunk alterego? Or vice versa?
I thought this would be a good opportunity to republish some of my earlier notes on Security and Identity and Signatures.
It is not unusual for decisions of trust to make a distinction between different identities of the same person. Let's say I have a friend called John. JOHN-SOBER and JOHN-DRUNK are two different identities, with recognizably different patterns of behaviour and risk. I am happy to lend my car keys to JOHN-SOBER, but not to JOHN-DRUNK.Can "user-centric" identity deal with these cases? How does "user-centric" identity deal with context-dependent identity?
If a person has a gun to his head, or his children are held hostage, his behaviour is likely to be uncharacteristic. ("You are not yourself today.") Signatures and voice patterns change under stressful conditions, including duress and torture. If this uncharacteristic behaviour is detected at a security checkpoint, then it might be appropriate to hinder a person's entry, until the identity difference is resolved.
This is about a difference in identity, not just a difference in behaviour. I am not refusing John my car keys because of his slurred speech; I am refusing them because he is drunk It may be his slurred speech that alerts me to the fact that he is drunk; but if he convinces me that his slurred speech on this occasion is a result of a visit to the dentist, I may let him have the car keys. Conversely, if he learns to speak normally even when drunk, I shall just have to find a different way to determine when he is drunk and when sober.
After his attempt to blow up the Houses of Parliament, Guy Fawkes was taken to the Tower of London and tortured to extract a confession. His signature - an important token of identity - degenerated under torture, and on his confession it is barely legible. There are serious questions about the validity and authenticity of confessions extracted under torture. The Guy Fawkes example indicates that the identity of the person signing the confession may be brutally transformed by torture, or perhaps even destroyed. We also know that identity and character may be tranformed by brainwashing - which we may sometimes regard as just another more subtle form of violence. In other contexts, identity may be altered by advertising or other modes of influence.
And can Hogwarts parents trust Professor Lupin with the care of their children? Not when there's a full moon. Remus Lupin has two identities - man and werwolf. As man, he is an excellent teacher. As werwolf he is a danger to himself and others. However, the werwolf identity manifests itself only at the full moon; at other times Lupin is perfectly safe. [Hogwarts Security]