Don't forget that Bucky is augmented himself. He's got his metal arm, plus whatever conditioning HYDRA subjected him to.
I'm just looking back at the previous films; I think it's a foregone conclusion that Captain America will win out. Every time someone has tried to introduce any sort of oversight, it has blown up in their faces; the World Security Council wanted to bomb Manhattan, while SHIELD was compromised by HYDRA. There's simply no way that any sort of regulation or oversight works, and just about every comic that explores the issue ultimately favours the independence of the heroes.