I have to say i'm intrigued by this thread and as per hazzy's request i'll add my own voice of Psychiatric expertise

to the fray
Being a twisted fuck is still being sick in the head though. Thats why they are a twisted fuck, because something in their head isn't right. And you gotta ask WHY it isn't right. Was he born that way? In which case its not really his fault, and he needs support and help. And if someone or something fucked him up as a kid then he still needs help and support.
To say he is "Sick" in terms of Diagnosed mental illness would be innacurate, this guy has in my (and the majority of my collegues) opinion an anti-social personality disorder, which in the strictest sense is NOT a mental illness
An anti social personality disorder can be "diagnosed" following these rules
Failure to conform to social norms with respect to lawful behaviors as indicated by repeatedly performing acts that are grounds for arrest
Deceitfulness, as indicated by repeatedly lying, use of aliases, or conning others for personal profit or pleasure;
Impulsivity or failure to plan ahead;
Irritability and aggressiveness, as indicated by repeated physical fights or assaults;
Reckless disregard for safety of self or others;
Consistent irresponsibility, as indicated by repeated failure to sustain consistent work behavior or honor financial obligations;
Lack of remorse, as indicated by being indifferent to or rationalizing having hurt, mistreated, or stolen from another
If it was illness there would be several reasons for it, misinterpretation of a situation, external visual or auditory hallucinations influencing his behaviour, external stimulii compelling him to act in a particular way
the lack of remorse and impulsive nature of alex added to the absolute disregard for others shows significant traits in place with personality disordered individuals
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Stephen Fry, who is about as intelligent as anyone could be, has Bi-Polar disorder.
No he f'n hasn't, Stephen Fry claimed he was Bi-polar, and manic depressive at different times, but he doesn’t have the associated “highs” to balance his low periods, this may indicate periods of depressed mood, but him labelling himself as bi-polar appears to be more for the excuse to be abrupt and eccentric
I think they were justified in doing that "cure" simply because it made him unable to rape, or kill again. It might be inhumane and you described it as torturing him, but the guy was messed up, and if they didn't do that whose to say he wouldn't have a longer list of victims when he was released? He was dangerous, so disabling him from doing that is justified I think. They even let him go free instead of serving his full sentence. If anything I believe he got off lucky.
Locking him up would've stopped him raping and killing too, at least while he was in jail. That "cure" made him a prisoner inside his own body. He thought he was getting off lucky, but if you were in jail and heard there was a way of getting out early, you would wouldn't you. He didn't know what it involved. And the fact its inhumane hasn't really got anything to do with the fact it's practical or not anyway. It would be practical to clamp his balls down somewhere so he could never move and his balls would be fucked just incase he did escape. But morally it was wrong, to "cure" him like that.
I agree in a fashion, some treatments can appear Inhumane, but ECT (electro Convulsion therapy) or “shock treatment” is viewed as a horrific torture to those who don’t understand it, its easy as a third party to pass judgement on treatments you don’t fully understand
This thread could be re titled mad or bad, the simple fact is, was Alex, Insane or just morally lacking
I’d go with the latter, the behaviour modification may have Re-educated his mind to be less hostile and more morally centred, but you can’t force a conscience to appear, sooner or later Alex would revert to his primal self