In my eyes people lose their human rights when they perpetrate certain acts.
If torturing Brady would have led to the finding of that childs body and given his poor mother some consolation before she died then why not?
There is mileage in what you say, but society does not lose its human rights, we rightly (and legally) live in a society, that enshrines the right to life, regardless of your actions..... this is very difficult to swallow sometimes, but it is what constitutes a civilised society, this of course means the the USA and China, cannot in my eyes be seen as civilised.
I think in this Utopia of yours that the criminal element would soon rule the roost with dire concequences.