If you don't think Bush's and Cheney's embrace of torture-as-policy has not had a profound effect, check out this instant response to Fort Hood from Mark Noonan in the neocon camp:
A terrible event - but I don’t want anyone to call it an “act of violence” or “a terrible tragedy”. It was an attack - one or more men decided with malice to attack a US military base. We need to get right down to the bottom of this - and, liberals, if the stories of accomplices in custody are true, this is where harsh interrogation might be needed: whoever was involved in this most emphatically does not have a right to remain silent.
So we go from torturing a foreign terror suspect who may know the whereabouts of a WMD that is about to go off imminently (the original Krauthammer position) to torturing American suspects in a shooting spree (suspect, I might add, that subsequently turned out to be mirages).
This is not a slippery slope; it's a well-greased waterslide to throwing out the entire American system of government.