One issue that the review focuses on is how to define torture. I have wondered about this myself, specifically with regard to punching or slapping people. Hitting people inflicts pain, of course, and so can count as torture. But it seems to me that there is a significant difference, one that might have moral significance, between hitting someone, perhaps out of frustration with their refusal to reveal potentially life-saving information, and coldly doing something designed specifically to inflict pain, such as sticking needles under a person's fingernails. Hitting someone, however wrong it might be, does not (usually) seem as inhuman as less expressive forms of torture. There are potential dangers in any suggestion that hitting prisoners is OK, of course, but I do think that there is some kind of difference that might be worth exploring between acts that inflict pain while still, in some sense, recognizing the humanity of one's victim and, on the other hand, ways of inflicting pain that treat the body as something like a means to extract something (information, surrender, whatever) from the mind within. (The mind-body problem seems relevant here, and the special badness of the second kind of torture seems related to the error of Cartesianism.)
Anscombe's writing on capital punishment might be helpful in understanding this issue. In her essay "The Dignity of the Human Being" she writes:
When capital punishment takes grisly forms [...] then it takes on a character which means that the victim's human dignity is being violated. The ancient Hebrew Law, the Torah, shews us why in an expression restricting punishments: a man was not to be given more than forty stripes 'lest thy brother become vile in thy sight'. [Deuteronomy 25:3]She goes on to suggest that methods of execution that lead people to place a hood over the victim's head violate this commandment. The hood is there precisely because the executed person would otherwise be vile in our sight. The hood does not change what is happening or its wrongness, and removing it would only reveal the wrongness, not remove it. I wonder whether we really have any methods of execution that would pass Anscombe's test (although she mentions the Athenian hemlock cup as one method that seems OK in this regard, so I suppose we could go back to that). I'm not saying that capital punishment is OK--I don't think it is--but I'm interested in the question whether the question of vileness (regardless of other considerations) rules out all contemporary execution methods. Jeffrie Murphy has some similar thoughts in his essay on "Cruel and Unusual Punishments." See also the first 30 minutes or so of Mr. Death: The Rise and Fall of Fred A. Leuchter, Jr., in which Mr. Leuchter misses the point memorably by trying to make execution dignified by hanging paintings on the wall of the execution chamber.
The central issue here appears to be respect for human dignity, for the dignity inherent in human being and human beings. Not only (at least some) capital punishment seems to be an assault on this dignity, but all "Cartesian" torture, and, indeed, Cartesianism itself too.