It goes out the window when there is actual uncertainty about who might win. Unrestricted submarine warfare was considered a war crime for most of peacetime, but as soon as it became a crucial strategic advantage that might turn the tide of the war, both sides started using it. The atom bomb would probably have been a war crime if it had been the losing side using it; as it is, it remains controversial.
Once one side wins the war, they become the dominant power again, and can enforce a definition of war crimes favorable to themselves. Such an event actually occurred with unrestricted submarine warfare: Admiral Nimitz testified for Karl Donitz at the latter's war crimes trial, because had unrestricted submarine warfare remained a war crime, the U.S. would have been guilty of it too.
'disposition matrix'
'gitmo'
'enhanced interrogation'
These are all gross violations of both the spirit and letter of international 'law', and was done by the most powerful country in the world.
Who can possibly believe war has rules that aren't completely ignored? Do people just ignore the horrific crimes committed by their own governments?
- US blows up various hospitals because "may contain insurgents"
- US blew up US citizen + his child without due process because "terrorism"
- US sanctions countries it doesn't like, causing civilians to starve/suffer/lack medicine
seems evident to me that one party doesn't really follow "the rules". how come they have a permanent seat at the UN security council? what punishment is prescribed for rule breakers? because it clearly isn't any loss of influence/prestige/sanctions/etc.
I have said this before, and this looks like a prime spot to say it again:
The only people who play fair are those who don't know how to cheat well enough.
If you are in a war and are in the lucky a situation that you can prolong the conflict without much negative effects, "keeping the game going" is in fact waging a war of attrition.