In my opinion, the Kellogg-Briand Pact failed because it was one of the silliest treaties ever (and because Hitler and the Japanese had no reason to obey it). So it's not surprising that I would think that a treaty like it would have no chance of working today.
The Kellogg-Briand Pact, essentially, outlawed war "as an instrument of national policy." So it's a law saying war is illegal. So what's so dumb about that?
Well... what's the point in saying war's illegal? Will that really stop some country from going to war?
If a country does go to war "illegally" the only way to punish them is to defeat them in a war, right? Well, countries only go to war by choice when they think they're going to win. So the treaty won't have any impact.
So overall then, my problems with the treaty are:
- There's no way to enforce the treaty short of going to war.
- Because of that, a country that wanted to go to war would feel free to do so as long as it thought it could win.
Until countries stop being greedy, pieces of paper won't stop them from going to war.