Some people saw the UDHR as an idealistic, pie-in-the-sky document that couldn't accomplish much except make nations feel angry or guilty. It couldn't force anyone to do anything.

But for sheer idealism, one treaty had it beat: the Kellogg-Briand Pact of 1928, dreamed up and named after the U.S. secretary of state and the French foreign minister. What made it seem so unrealistic? After all, it only did one little thing.

It outlawed war.

And just about every nation in existence at the time signed it.

We know what you're thinking, all you Shmoop history enthusiasts: outlaw war? Ha-ha, that's a good one. What about Japan invading Manchuria two years after the pact? Or Italy invading Ethiopia in 1935? Or Hitler invading everybody starting in 1939? War declared illegal? If you believe that, we've got a bridge we'd like to sell you.

But was the pact really just a peacenik fantasy like the UDHR was to some? A human rights wish list that would never amount to anything? A recent book by two Yale Law School profs says no. Their thesis is that the reasons that there haven't been that many wars between nations since the end of World War II (although there have been plenty of internal conflicts) is actually because war was since seen as illegal. Prior to the pact, war was understood as just something nations do, just another aspect of foreign policy. Want more territory or natural resources? Just invade your neighbor and get it. Great example: the Manifest Destiny-inspired Mexican-American War.

The authors even see World War II as something that vindicated the effectiveness of the Kellogg-Briand Pact because the war was fought to punish Japan and Germany for their aggressive land grabs. Since 1945, they argue, there have been invasions and occupations, but most nations have been punished by the international community, and few have held on to the territory they invaded. When Saddam Hussein invaded Kuwait in 1990, for example, no nation in the world thought it was a legitimate act. The U.N. condemned the invasion, and they authorized forces led by the U.S. to send Iraq packing.

You could think about the UDHR in a similar way. Sure, it couldn't demand anything from the global community, but it changed expectations about how nations should behave. And plenty of them incorporated the rights enumerated in the declaration into their own constitutions and domestic policies.

Sometimes pie in the sky can be downright delicious.