Disclaimer: There are spoilers of Captain America: Civil War in what follows. I also realize I’m being a huge nerd about this, and it is necessary to suspend belief to watch superhero movies. Also, I’m a philosopher, not a political scientist, so my understanding of U.N. procedures is rudimentary.
It was curious to me that in Captain America: Civil War the writers decided to use an existing organization–the United Nations–instead of continuing to use fictional groups like the World Security Council, S.H.I.E.L.D., etc.
As I understand it, the purpose of the UN is to do things like mediate and maintain world peace, promote human rights, and protect the environment. So, ideally they are in the business of promoting humanitarianism.
The UN isn’t the world police, and there’s no such thing as a world army. The UN Security Council can use armed coalition forces to maintain peace and security, but those forces are voluntarily provided by nation-states (and the UN can’t force a nation to send troops). The UN also has an International Court of Justice, but it only looks at cases brought about by nation-states against other nation-states (and it doesn’t even really have jurisdiction over them).
So, to have a UN panel that would determine when a group of superheroes would–what? be used as a “peacekeepers”?–is dubious to begin with.