There is, in my view, a fundamental difference between terrorists and decent human beings.
Human rights are meant to affirm the value of being human, the right to your thoughts, actions. It is not meant to be manipulated in order to give you the right to harm others.
A terrorist on the other hand, does not affirm the value of other humans. They affirm instead their own convictions and their right to harm others to protect their own convictions. If they had directed their ire against those who perpetuated the perceived injustice upon them, it is not so bad. But they do so against innocent human beings.
Should therefore terrorists come under the purview of human rights, just because they are classified as 'human being'? And in turn have their rights to harm others affirmed?
But having said all these, technology has advanced so much that traditional torture methods are no longer neccessary.