Basically because the USA is world's only superpower and they do what they want regardless of laws. It's not just Cheney but the entire Bush administration that have committed these crimes. Also not everyone sees these as crimes, there are more people like Colpy who thinks he's a good man for massacring a bunch Muslims.
International Law is a bad joke, rightfully ignored by every nation on earth when broader interests are involved. We are NOT a federation of nations, but a competitive world in which conflict often settles our most serious differences. There is no consensus on what ideas, what systems, what culture best serves the needs of man.
But only one operates on the foundation of the right of the individual, and the rule of law as passed down by the elected representatives of those individuals.
And it ain't the Chinese model, nor the Ba'athist model, nor the Islamic model, it is ONLY the model of the west.
War is diplomacy by other means, to paraphrase von Clauswitz.
Ever has it been so, and I fear greatly for our liberty and our "civilization" should it ever change.
You never ONCE heard me say (or read me write) that Cheney is a "good" man.